Tilahun Yeshambel
email: tilahun.yeshambel@uog.edu

Josiane Mothe
email: josiane.mothe@irit.fr

Yaregal Assabie
email: yaregal.assabie@aau.edu.

Amharic Adhoc Information Retrieval System Based on Morphological Features

Keywords: information retrieval, adhoc retrieval, Amharic, complex morphology, corpus, resources

Information retrieval (IR) is one of the most important research and development areas due to the explosion of digital data and the need of accessing relevant information from huge corpora. Although IR systems function well for technologically advanced languages such as English, this is not the case for morphologically complex, under-resourced and less-studied languages such as Amharic. Amharic is a Semitic language characterized by a complex morphology where thousands of words are generated from a single root form through inflection and derivation. This has made the development of Amharic natural language processing (NLP) tools a challenging task. Amharic adhoc retrieval also faces challenges due to scarcity of linguistic resources, tools and standard evaluation corpora. In this research work, we investigate the impact of morphological features on the representation of Amharic documents and queries for adhoc retrieval. We also analyze the effects of stem-based and root-based text representation, and proposed new Amharic IR system architecture. Moreover, we present the resources and corpora we constructed for evaluation of Amharic IR systems and other NLP tools. We conduct various experiments with a TREC-like approach for Amharic IR test collection using a standard evaluation framework and measures. Our findings show that root-based text representation outperforms the conventional stem-based representation on Amharic IR.

Introduction

Searching digital information on the Web or a large corpus has become part of the human daily life. Information Retrieval (IR) is concerned with searching relevant documents to a user's query from a document collection. Both the research community and the industry have been very active in this field for more than 60 years [START_REF] Sanderson | The history of information retrieval research[END_REF]. Nowadays, IR has gained much attention due to the explosion of digital data and the need of accessing relevant information from huge corpus quickly and accurately.

The ability of an IR system to retrieve relevant documents effectively should be tested and its performance should be evaluated systematically. Performance evaluation of an IR system is indeed very crucial for scientific progress [START_REF] Buckley | Retrieval system evaluation[END_REF][START_REF] Ferro | CLEF 15th Birthday: Past, Present, and Future[END_REF]. IR has an old history of evaluation. In adhoc retrieval, where the task for the system is to retrieve relevant documents for a given query within a fixed size corpus, both the evaluation framework and effectiveness measures are well established. Test collections are the most widely used resources for performance evaluation [START_REF] Clough | Evaluating the performance of information retrieval systems using test collections[END_REF]. A standard adhoc retrieval test collection consists of three components: a corpus of documents to be searched in, a set of users' information needs or topics, and the associated relevance judgments indicating which documents are relevant for which topics. A large number of shared tasks rely on such collections. Some of the well-known text collections and evaluation programs are Cranfield project [START_REF] Cleverdon | The evaluation of systems used in information retrieval[END_REF], Text REtrieval Conference (TREC) and more specifically TREC adhoc [START_REF] Harman | Overview of the second text retrieval conference (TREC-2)[END_REF], Cross-Language Evaluation Forum (CLEF) [START_REF] Ferro | CLEF 15th Birthday: Past, Present, and Future[END_REF], and NACSIS Test Collection for Information Retrieval (NTCIR) [START_REF] Kando | The NTCIR Workshop: The first Evaluation Workshop on Japanese Text Retrieval and Cross-Lingual Information Retrieval[END_REF]. The IR international conferences such as TREC, CLEF, NTCIR, INEX, and FIRE are held based on their own test collections.

IR systems work based on documents produced in natural language and consequently, the performance of IR is affected by the characteristics of the language [START_REF] Moukdad | Comparison of Root and Stemming Techniques for the Retrieval of Arabic Documents[END_REF]. As a result, NLP has been employed to improve the effectiveness of IR systems. For example, NLP tools and resources provide a means to find index terms and query terms that improve search results. Linguistic variation has significant impact on IR effectiveness as it leads to the omission of relevant documents to users' queries [START_REF] Moukdad | Comparison of Root and Stemming Techniques for the Retrieval of Arabic Documents[END_REF]. This calls for the need of dealing with language specific issues to improve the performance of IR systems. Thus, NLP has long attracted the attention of the IR community [START_REF] Smeaton | Progress in the application of natural language processing to information retrieval tasks[END_REF][START_REF] Jackson | Natural Language Processing for Online Applications: Text Retrieval, Extraction and Categorization[END_REF][START_REF] Cambria | Jumping NLP curves: A review of natural language processing research[END_REF]. The morphology, orthography, tokenization, syntax, semantics, and compound splitting of a language are some of the issues to be considered while developing an IR system. Many languages have several word forms generated from a single word due to morphology and orthography. Identifying the basic units of words is more difficult for morphologically complex languages than for simple languages [START_REF] Bojanowski | Enriching word vectors with subword information[END_REF]. Performing simple matching between words generated from the same root is not sufficient while retrieving relevant documents to a user query [START_REF] Musaid | Arabic Information Retrieval System-Based on Morphological Analysis (AIRSMA): A Comparative Study of Word, Stem, Root and Morpho-Semantic Methods[END_REF]. Numerous researches have been conducted to develop IR system, to construct resources and corpora for resourceful languages such as English, French, and German. This is not, however, the case for under-resourced languages such as Amharic [START_REF] El-Haj | Creating language resources for under-resourced languages: Methodologies, and experiments with Arabic[END_REF].

Amharic is one of the under-resourced languages where, in comparison with technologically advanced languages, few attempts have been made to develop Amharic NLP tools, applications, resources and corpora [START_REF] Yifru | Part-of-speech tagging for under-resourced and morphologically rich languages: The case of Amharic, HLTD[END_REF][START_REF] Mulugeta | Learning morphological rules for Amharic verbs using inductive logic programming[END_REF][START_REF] Assabie | Development of Amharic Morphological Analyzer[END_REF]. Among the few efforts are the development of stemmer [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF][START_REF] Alemu | An Amharic stemmer: Reducing words to their citation forms[END_REF], morphological analyzer [START_REF] Mulugeta | Learning morphological rules for Amharic verbs using inductive logic programming[END_REF][START_REF] Amsalu | Finite state morphology of Amharic[END_REF][START_REF] Gasser | Horn Morpho: A system for morphological processing of Amharic, Oromo, and Tigrinya[END_REF][START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF], part-of-speech tagger [START_REF] Yifru | Part-of-speech tagging for under-resourced and morphologically rich languages: The case of Amharic, HLTD[END_REF][START_REF] Sisay | Part-of-speech tagging for Amharic using conditional random fields[END_REF][START_REF] Gamback | Methods for Amharic part-of-speech tagging[END_REF], resources [START_REF] Alemayehu | The effectiveness of stemming for information retrieval in Amharic. Program Electron[END_REF][START_REF] Mindaye | Design and implementation of Amharic search engine[END_REF][START_REF] Samuel | Classifying Amharic news text using self-organizing maps[END_REF], and corpus [START_REF] Gamback | Tagging and verifying an Amharic news corpus[END_REF][START_REF] Abate | Parallel corpora for Bi-Lingual English-Ethiopian languages statistical machine translation[END_REF][START_REF] Demeke | Manual annotation of Amharic news items with part-of-speech tags and its challenges[END_REF]. However, the existing tools, resources and corpora are not fully functional, limiting their usability for IR [START_REF] Yeshambel | Evaluation of corpora, resources and tools for Amharic information retrieval[END_REF]. Furthermore, the number of studies reported on Amharic IR and related applications are considerably limited compared to what is carried out for other languages such as English. The morphological complexity of Amharic creates a challenge on the development and retrieval effectiveness of Amharic IR. Thus, in order to come up with an effective IR system, one has to deal with the complex morphological features of the language which itself leads to complex grammatical structure. As a result, finding effective term (word) representation for documents and queries has been an issue of theoretical discussion in Amharic IR.

In many languages, the use of surface forms of words to represent documents and queries is not a choice due to the proliferation of words that can be generated from a single root form. Thus, the word forms that are considered for document and query representation are stems and roots. Although some efforts have been made to develop Amharic IR systems using stems, the effectiveness of the systems with respect to the use of various forms has not been systematically analyzed [START_REF] Yeshambel | Amharic document representation for adhoc retrieval[END_REF]. This current research analyzes the use of stems and roots for content representation and investigates their effects on Amharic IR.

It is noted that a reference collection, annotated corpora and scientifically built resources would assist to carry out more research and development works on Amharic IR and NLP. To advance research on the development of Amharic NLP tools and IR system, there should be scientifically built resources and test collections. The development of Amharic NLP tools is a non-trivial task because of its complex morphology. Thus, the creation of morphologically annotated Amharic corpus is a long-sought resource for the research community. Morphological annotation of a language is the process of assigning linguistic information such as part-of-speech (POS) and morphological features to recognize each word in a document [START_REF] Khoufi | Statistical-based system for morphological annotation of Arabic texts[END_REF]. Morphological analyzers can help to automatically annotate text corpus. With regard to Amharic, there have been few attempts to develop morphological analyzers [START_REF] Mulugeta | Learning morphological rules for Amharic verbs using inductive logic programming[END_REF][START_REF] Gasser | Horn Morpho: A system for morphological processing of Amharic, Oromo, and Tigrinya[END_REF][START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. These tools are at a prototype stage and they are also limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: [START_REF] Sanderson | The history of information retrieval research[END_REF] to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language 2.1. Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel / / and the other six orders represent modifications with vowels in the order of / . 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: [START_REF] Sanderson | The history of information retrieval research[END_REF] to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually u/, / Appl. Sci. 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: [START_REF] Sanderson | The history of information retrieval research[END_REF] to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

2.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually i/, / Appl. Sci. 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: [START_REF] Sanderson | The history of information retrieval research[END_REF] to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually a/, / Appl. Sci. 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: [START_REF] Sanderson | The history of information retrieval research[END_REF] to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually e/, / Appl. Sci. 2022, 12, x FOR PEER REVIEW 3 of limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes difficult to create annotated corpus automatically. Moreover, there is lack of standa reference collection making it a major impediment to the development of Amharic IR an NLP tools. The objective of this research work is: [START_REF] Sanderson | The history of information retrieval research[END_REF] to promote publicly accessible Am haric resources including a standard test collection for IR, morphologically annotate corpora and compiled stopwords list; and (2) to design Amharic IR system by inves gating the optimal representation of documents and queries considering both root-base and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic langua and its morphology. Section 3 discusses related work. In Section 4, we present the pr posed Amharic IR system architecture along with various options to represent Amhar documents and queries. Section 5 presents the evaluation framework of the propose Amharic adhoc retrieval system including the presentation of the resources and corpor experimental setup, and experimental results. In Section 6, we present our conclusio and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having a estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spok Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken Ethiopia, Amharic is the lingua franca and the most literary language serving as a m dium of instruction in the education system of the country for a long period. Amhar uses Ethiopic alphabet and has 34 base characters along with modifications on the r spective base characters. The alphabet is conveniently written in a tabular format seven columns.

The first column represents the basic form with vowel ኧ /ə/ and t other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the followin modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there a labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. T language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arab numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated throug inflectional and derivational processes from other word forms. Many surface forms words can be formed from a base form through complex affixation, reduplication, an Semitic stem interdigitation. Amharic words can be marked for a number of function For example, a verb can be marked for a combination of person, case, gender, numbe tense, aspect, and mood. An Amharic word might take up to four prefixes and five su fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructe from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipr cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singul subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for pe fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gene ated from an Amharic root or its stems by changing the shape of characters in a stem root, inserting vowels between root radicals, reduplicating one of the characters of the ste or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates f verbal words. However, all variants have a single root representation template. The majo ity of words in the language are generated from verbal roots. Nouns, adjectives, and a verbs can be derived from verbal roots. The derivation of words from verbal roots usual Amharic adhoc retrieval system including the presentation of the resources experimental setup, and experimental results. In Section 6, we present ou and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia curren estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most comm Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages a Ethiopia, Amharic is the lingua franca and the most literary language serv dium of instruction in the education system of the country for a long peri uses Ethiopic alphabet and has 34 base characters along with modification spective base characters. The alphabet is conveniently written in a tabul seven columns. The first column represents the basic form with vowel ኧ /ə/ six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following mod /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialize such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon) colon), etc. It also borrows some punctuation marks such as '?' and '!' from bet. Although Ethiopic alphabet has numeral system, the Arabic numeral sys most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be gener inflectional and derivational processes from other word forms. Many surf words can be formed from a base form through complex affixation, redup Semitic stem interdigitation. Amharic words can be marked for a number For example, a verb can be marked for a combination of person, case, gen tense, aspect, and mood. An Amharic word might take up to four prefixes fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwa constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negati causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third p object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/ of words can be gener-ated from an Amharic root or its stems by changing characters in a stem or root, inserting vowels between root radicals, redupli the characters of the stem or word itself, and by adding affixes on stems [2 multiple stem templates for verbal words. However, all variants have a representation template. The major-ity of words in the language are generated roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The words from verbal roots usually /, and / 3 of 29 ilability of full-fledged low-level Amharic NLP tools makes it d corpus automatically. Moreover, there is lack of standard it a major impediment to the development of Amharic IR and this research work is: [START_REF] Sanderson | The history of information retrieval research[END_REF] to promote publicly accessible Amstandard test collection for IR, morphologically annotated words list; and (2) to design Amharic IR system by investitation of documents and queries considering both root-based ntations. s organized as follows. Section 2 describes Amharic language n 3 discusses related work. In Section 4, we present the prorchitecture along with various options to represent Amharic ction 5 presents the evaluation framework of the proposed tem including the presentation of the resources and corpora, perimental results. In Section 6, we present our conclusion earch directions. language of the government of Ethiopia currently having an er 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken ld after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in gua franca and the most literary language serving as a meeducation system of the country for a long period. Amharic has 34 base characters along with modifications on the rehe alphabet is conveniently written in a tabular format of olumn represents the basic form with vowel ኧ /ə/ and the odifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / /. For example, the base character በ /bə/ has the following i/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The unctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), n), etc. It also borrows some punctuation marks such as '?' . Although Ethiopic alphabet has numeral system, the Arabic ost commonly used by Amharic. morphology where many words could be generated through l processes from other word forms. Many surface forms of a base form through complex affixation, reduplication, and . Amharic words can be marked for a number of functions. marked for a combination of person, case, gender, number, n Amharic word might take up to four prefixes and five sufword ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed position/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-ር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular erb/, አቸው /ʔətʃəwɨ third person plural object marker for pere/, and ና /na conjunction/). Thousands of words can be generor its stems by changing the shape of characters in a stem or en root radicals, reduplicating one of the characters of the stem g affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for variants have a single root representation template. The majore are generated from verbal roots. Nouns, adjectives, and aderbal roots. The derivation of words from verbal roots usually o/. For example, the base character /b / has the following modifications: /bu/, /bi/, /ba/, /be/, /b posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually /, and /bo/. Furthermore, there are labialized characters such as /bwa/, /mwa/, /twa/, /qwa/, /rwa/, etc. The language has also its own punctuations such as ' ' (full stop), ' ' (comma), ' ' (semicolon), ' ' (colon), ' ' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word /jalas 2, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: [START_REF] Sanderson | The history of information retrieval research[END_REF] to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually t sas r l. Sci. 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: [START_REF] Sanderson | The history of information retrieval research[END_REF] to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually kwat Appl. Sci. 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: [START_REF] Sanderson | The history of information retrieval research[END_REF] to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually w Appl. Sci. 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: [START_REF] Sanderson | The history of information retrieval research[END_REF] to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually n Appl. Sci. 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: [START_REF] Sanderson | The history of information retrieval research[END_REF] to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually na/ is constructed from four prefixes ( /j preposition/, / W 3 of 29 mited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it ifficult to create annotated corpus automatically. Moreover, there is lack of standard ference collection making it a major impediment to the development of Amharic IR and LP tools. The objective of this research work is: [START_REF] Sanderson | The history of information retrieval research[END_REF] to promote publicly accessible Amaric resources including a standard test collection for IR, morphologically annotated orpora and compiled stopwords list; and (2) to design Amharic IR system by investiating the optimal representation of documents and queries considering both root-based nd stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language nd its morphology. Section 3 discusses related work. In Section 4, we present the proosed Amharic IR system architecture along with various options to represent Amharic ocuments and queries. Section 5 presents the evaluation framework of the proposed mharic adhoc retrieval system including the presentation of the resources and corpora, xperimental setup, and experimental results. In Section 6, we present our conclusion nd put forward further research directions.

. Amharic Language

.

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an stimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken emitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in thiopia, Amharic is the lingua franca and the most literary language serving as a meium of instruction in the education system of the country for a long period. Amharic ses Ethiopic alphabet and has 34 base characters along with modifications on the repective base characters. The alphabet is conveniently written in a tabular format of even columns.

The first column represents the basic form with vowel ኧ /ə/ and the ther six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / a/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following odifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are bialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The nguage has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), ' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' nd '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic umeral system is rather most commonly used by Amharic.

.

Amharic Morphology

Amharic has complex morphology where many words could be generated through flectional and derivational processes from other word forms. Many surface forms of ords can be formed from a base form through complex affixation, reduplication, and emitic stem interdigitation. Amharic words can be marked for a number of functions. or example, a verb can be marked for a combination of person, case, gender, number, nse, aspect, and mood. An Amharic word might take up to four prefixes and five sufxes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed om four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciproal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular l R PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: [START_REF] Sanderson | The history of information retrieval research[END_REF] to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually negation/, / 2, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: [START_REF] Sanderson | The history of information retrieval research[END_REF] to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular s Appl. Sci. 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: [START_REF] Sanderson | The history of information retrieval research[END_REF] to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually causative/, /t reciprocal/); the perfective verb ( / 3 of 29 ope. The unavailability of full-fledged low-level Amharic NLP tools makes it reate annotated corpus automatically. Moreover, there is lack of standard llection making it a major impediment to the development of Amharic IR and he objective of this research work is: [START_REF] Sanderson | The history of information retrieval research[END_REF] to promote publicly accessible Amces including a standard test collection for IR, morphologically annotated compiled stopwords list; and (2) to design Amharic IR system by investiptimal representation of documents and queries considering both root-based sed text representations. t of this paper is organized as follows. Section 2 describes Amharic language phology. Section 3 discusses related work. In Section 4, we present the proric IR system architecture along with various options to represent Amharic and queries. Section 5 presents the evaluation framework of the proposed oc retrieval system including the presentation of the resources and corpora, l setup, and experimental results. In Section 6, we present our conclusion ard further research directions.

anguage Writing System ic is the working language of the government of Ethiopia currently having an opulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken uage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in haric is the lingua franca and the most literary language serving as a metruction in the education system of the country for a long period. Amharic ic alphabet and has 34 base characters along with modifications on the ree characters. The alphabet is conveniently written in a tabular format of ns. The first column represents the basic form with vowel ኧ /ə/ and the ers represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following s: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are haracters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The s also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), ፦' (preface colon), etc. It also borrows some punctuation marks such as '?'

Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic tem is rather most commonly used by Amharic.

Morphology

ic has complex morphology where many words could be generated through and derivational processes from other word forms. Many surface forms of e formed from a base form through complex affixation, reduplication, and interdigitation. Amharic words can be marked for a number of functions. , a verb can be marked for a combination of person, case, gender, number, t, and mood. An Amharic word might take up to four prefixes and five sufr example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed efixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-s r EVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: [START_REF] Sanderson | The history of information retrieval research[END_REF] to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually 'tie'/); and four suffixes ( /ku first person singular subject marker for perfect verb/, / W 3 of 29 imited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it ifficult to create annotated corpus automatically. Moreover, there is lack of standard eference collection making it a major impediment to the development of Amharic IR and LP tools. The objective of this research work is: [START_REF] Sanderson | The history of information retrieval research[END_REF] to promote publicly accessible Amaric resources including a standard test collection for IR, morphologically annotated orpora and compiled stopwords list; and (2) to design Amharic IR system by investiating the optimal representation of documents and queries considering both root-based nd stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language nd its morphology. Section 3 discusses related work. In Section 4, we present the proosed Amharic IR system architecture along with various options to represent Amharic ocuments and queries. Section 5 presents the evaluation framework of the proposed mharic adhoc retrieval system including the presentation of the resources and corpora, xperimental setup, and experimental results. In Section 6, we present our conclusion nd put forward further research directions.

. Amharic Language .

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an stimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken emitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in thiopia, Amharic is the lingua franca and the most literary language serving as a meium of instruction in the education system of the country for a long period. Amharic ses Ethiopic alphabet and has 34 base characters along with modifications on the repective base characters. The alphabet is conveniently written in a tabular format of even columns.

The first column represents the basic form with vowel ኧ /ə/ and the ther six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / a/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following odifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are abialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The anguage has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), ፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' nd '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic umeral system is rather most commonly used by Amharic.

.

Amharic Morphology

Amharic has complex morphology where many words could be generated through nflectional and derivational processes from other word forms. Many surface forms of ords can be formed from a base form through complex affixation, reduplication, and emitic stem interdigitation. Amharic words can be marked for a number of functions.

or example, a verb can be marked for a combination of person, case, gender, number, ense, aspect, and mood. An Amharic word might take up to four prefixes and five sufixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed t pl. Sci. 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: [START_REF] Sanderson | The history of information retrieval research[END_REF] to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually w , x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: [START_REF] Sanderson | The history of information retrieval research[END_REF] to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually third person plural object marker for perfective verb/, /n 3 of 29 pe. The unavailability of full-fledged low-level Amharic NLP tools makes it eate annotated corpus automatically. Moreover, there is lack of standard ction making it a major impediment to the development of Amharic IR and e objective of this research work is: [START_REF] Sanderson | The history of information retrieval research[END_REF] to promote publicly accessible Ames including a standard test collection for IR, morphologically annotated ompiled stopwords list; and (2) to design Amharic IR system by investiimal representation of documents and queries considering both root-based d text representations. of this paper is organized as follows. Section 2 describes Amharic language ology. Section 3 discusses related work. In Section 4, we present the proic IR system architecture along with various options to represent Amharic d queries. Section 5 presents the evaluation framework of the proposed c retrieval system including the presentation of the resources and corpora, setup, and experimental results. In Section 6, we present our conclusion rd further research directions.

nguage riting System

is the working language of the government of Ethiopia currently having an ulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken age in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in haric is the lingua franca and the most literary language serving as a meuction in the education system of the country for a long period. Amharic alphabet and has 34 base characters along with modifications on the recharacters. The alphabet is conveniently written in a tabular format of s. The first column represents the basic form with vowel ኧ /ə/ and the other resent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ . For example, the base character በ /bə/ has the following modifications: ቡ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters a/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface also borrows some punctuation marks such as '?' and '!' from Latin alpha-Ethiopic alphabet has numeral system, the Arabic numeral system is rather ly used by Amharic. orphology has complex morphology where many words could be generated through d derivational processes from other word forms. Many surface forms of formed from a base form through complex affixation, reduplication, and interdigitation. Amharic words can be marked for a number of functions. a verb can be marked for a combination of person, case, gender, number, and mood. An Amharic word might take up to four prefixes and five sufor example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is rom four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands be gener-ated from an Amharic root or its stems by changing the shape of a stem or root, inserting vowels between root radicals, reduplicating one of of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root template. The major-ity of words in the language are generated from verbal adjectives, and ad-verbs can be derived from verbal roots. The derivation of erbal roots usually accusative/, and /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually involves stem formation followed by word formation. Amharic roots are the base of stems which in turn are the base of many surface forms of words (see Table 1).

Root Stem Word in Surface Form

--/n-g-r/

/n et. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather ost commonly used by Amharic.

.

Amharic Morphology

Amharic has complex morphology where many words could be generated through nflectional and derivational processes from other word forms. Many surface forms of ords can be formed from a base form through complex affixation, reduplication, and emitic stem interdigitation. Amharic words can be marked for a number of functions. or example, a verb can be marked for a combination of person, case, gender, number, ense, aspect, and mood. An Amharic word might take up to four prefixes and five sufixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is onstructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ausative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / u first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural bject marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands f words can be gener-ated from an Amharic root or its stems by changing the shape of haracters in a stem or root, inserting vowels between root radicals, reduplicating one of he characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are ultiple stem templates for verbal words. However, all variants have a single root epresentation template. The major-ity of words in the language are generated from verbal oots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of ords from verbal roots usually g r bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually / /n bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually g ru/, /n

bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually g r Appl. Sci. 2022, 12, x FOR PEER REVIEW 4 of 29 involves stem formation followed by word formation. Amharic roots are the base of stems which in turn are the base of many surface forms of words (see Table 1).

Word formation from verbal stems is completed by attaching different affixes such as infinitive, gerund, person, gender, number, case, passive, tense/aspect, genitive, accusative, mood, etc. For example, from the verbal stem ነገር /nəgərɨ/, it is possible to generate the following words: ነገርኳቸው /nəgərɨkwatʃəwɨ 'I told them'/, ተነገረች /tənəgərətʃɨ 'she has been told'/, ነገረኝ /nəgərəɲɨ 'he told me'/, ነገርሽው /nəgərɨʃɨwɨ 'you told him'/, etc. Words generated from stems could have both prefixes and suffixes. For example, the word ስላልተደወለላቸውና /sɨlalɨtədəwələlatʃəwɨna/ has three prefixes (ስለ /sɨlə preposition/, አል /ʔəlɨ negation/, ተ /tə passivizer/), a perfective stem ደወል /dəwəlɨ/ and four suffixes (ኧ /ə/, ል /lɨ beneficative/, አቸው /ʔətʃəwɨ [3rd person, plural]/, ና /na conjunction/). Many words are also formed through inflectional process. Amharic nouns and adjectives are inflected with number, person, gender, definiteness, etc. to form many words in surface forms. Some Amharic functional words such as prepositions, conjunctions, etc. also undergo morphological process to form variants. They exist either by merging with each other or by affixation with other words. For example, from the word ሌላ /lela 'other'/ variants that could be generated include ሌላዎች /lelawətʃɨ/, የሌላ /jəlela/, ከሌላ /kəlela/, በሌላ /bəlela/, የሌሎች /jəlelotʃɨ/, ስለሌሎቻችን /sɨləlelotʃatʃɨnɨ/, ሌላው /lelawɨ/, etc.

In general, the formation of thousands of words, especially from verbal roots makes the analysis, annotation and tagging of Amharic text a difficult task. This level of morphological complexity has significantly contributed to the difficulty of producing lin-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually /, /m n bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually g re/, etc. /nag r colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually / /t nag r colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually /, /m nag rat /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually n colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually /, etc. /n g punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually r punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually / /lin g punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually r Appl. Sci. 2022, 12, x FOR PEER REVIEW 4 of 29 involves stem formation followed by word formation. Amharic roots are the base of stems which in turn are the base of many surface forms of words (see Table 1).

Word formation from verbal stems is completed by attaching different affixes such as infinitive, gerund, person, gender, number, case, passive, tense/aspect, genitive, accusative, mood, etc. For example, from the verbal stem ነገር /nəgərɨ/, it is possible to generate the following words: ነገርኳቸው /nəgərɨkwatʃəwɨ 'I told them'/, ተነገረች /tənəgərətʃɨ 'she has been told'/, ነገረኝ /nəgərəɲɨ 'he told me'/, ነገርሽው /nəgərɨʃɨwɨ 'you told him'/, etc. Words generated from stems could have both prefixes and suffixes. For example, the word ስላልተደወለላቸውና /sɨlalɨtədəwələlatʃəwɨna/ has three prefixes (ስለ /sɨlə preposition/, አል /ʔəlɨ negation/, ተ /tə passivizer/), a perfective stem ደወል /dəwəlɨ/ and four suffixes (ኧ /ə/, ል /lɨ beneficative/, አቸው /ʔətʃəwɨ [3rd person, plural]/, ና /na conjunction/). Many words are also formed through inflectional process. Amharic nouns and adjectives are inflected with number, person, gender, definiteness, etc. to form many words in surface forms. Some Amharic functional words such as prepositions, conjunctions, etc. also undergo morphological process to form variants. They exist either by merging with each other or by affixation with other words. For example, from the word ሌላ /lela 'other'/ variants that could be generated include ሌላዎች /lelawətʃɨ/, የሌላ /jəlela/, ከሌላ /kəlela/, በሌላ /bəlela/, የሌሎች /jəlelotʃɨ/, ስለሌሎቻችን /sɨləlelotʃatʃɨnɨ/, ሌላው /lelawɨ/, etc.

In general, the formation of thousands of words, especially from verbal roots makes the analysis, annotation and tagging of Amharic text a difficult task. This level of morphological complexity has significantly contributed to the difficulty of producing linpunctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually /, /sin g punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually rat six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually w punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually /, etc.

--/l-m-d/ /l m d such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually / /l m d /, /t l m d /, etc. /lam d /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually / /m lam du/, / Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually lam d t uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually /, etc. /l /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually m /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually d /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually / /l /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually m /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually dat dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually n /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually /, /b l /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually m /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually dwa/, etc.

--/s-k-r/ /s ix orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters uch as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own unctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface olon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-et. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather ost commonly used by Amharic.

.2. Amharic Morphology

Amharic has complex morphology where many words could be generated through nflectional and derivational processes from other word forms. Many surface forms of ords can be formed from a base form through complex affixation, reduplication, and emitic stem interdigitation. Amharic words can be marked for a number of functions. or example, a verb can be marked for a combination of person, case, gender, number, ense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-ixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is onstructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ausative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / u first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural bject marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands f words can be gener-ated from an Amharic root or its stems by changing the shape of haracters in a stem or root, inserting vowels between root radicals, reduplicating one of he characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are ultiple stem templates for verbal words. However, all variants have a single root epresentation template. The major-ity of words in the language are generated from verbal oots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of ords from verbal roots usually kar six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually / /s six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually karu/, /b s six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually karat Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually w six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually /, etc. /s k r seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually

/ /s k r /, /
The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually s k r /, /s k ru/, etc. /s pective base characters. The alphabet is conveniently written in a tabular format of even columns. The first column represents the basic form with vowel ኧ /ə/ and the other ix orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters uch as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own unctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface olon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-et. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather ost commonly used by Amharic.

.2. Amharic Morphology

Amharic has complex morphology where many words could be generated through nflectional and derivational processes from other word forms. Many surface forms of ords can be formed from a base form through complex affixation, reduplication, and emitic stem interdigitation. Amharic words can be marked for a number of functions. or example, a verb can be marked for a combination of person, case, gender, number, ense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-ixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is onstructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ausative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / u first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural bject marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands f words can be gener-ated from an Amharic root or its stems by changing the shape of haracters in a stem or root, inserting vowels between root radicals, reduplicating one of he characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are ultiple stem templates for verbal words. However, all variants have a single root epresentation template. The major-ity of words in the language are generated from verbal oots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of ords from verbal roots usually k r spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually / /m s spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually k r/, /

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually l m s spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually k re/, /s spective base characters. The alphabet is conveniently written in a tabular format seven columns. The first column represents the basic form with vowel ኧ /ə/ and the ot six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized charact such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its o punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (pref colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alp bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rath most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated throu inflectional and derivational processes from other word forms. Many surface forms words can be formed from a base form through complex affixation, reduplication, a Semitic stem interdigitation. Amharic words can be marked for a number of functio For example, a verb can be marked for a combination of person, case, gender, numb tense, aspect, and mood. An Amharic word might take up to four prefixes and five s fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plu object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousan of words can be gener-ated from an Amharic root or its stems by changing the shape characters in a stem or root, inserting vowels between root radicals, reduplicating one the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There multiple stem templates for verbal words. However, all variants have a single r representation template. The major-ity of words in the language are generated from ver roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation words from verbal roots usually k ru/, etc. Amharic verbal stems are formed from verbal roots by inserting vowels between radicals (consonants). For example, the verbal stems /n

Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually g r Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually /, /lam d Ethiopia, Amharic is the lingua franca and the most literary language serving as a dium of instruction in the education system of the country for a long period. Amh uses Ethiopic alphabet and has 34 base characters along with modifications on th spective base characters. The alphabet is conveniently written in a tabular form seven columns. The first column represents the basic form with vowel ኧ /ə/ and the o six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ / /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modification /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized chara such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (pre colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin al bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is ra most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated thro inflectional and derivational processes from other word forms. Many surface form words can be formed from a base form through complex affixation, reduplication, Semitic stem interdigitation. Amharic words can be marked for a number of funct For example, a verb can be marked for a combination of person, case, gender, num tense, aspect, and mood. An Amharic word might take up to four prefixes and five fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person p object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thous of words can be gener-ated from an Amharic root or its stems by changing the shap characters in a stem or root, inserting vowels between root radicals, reduplicating on the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. Ther multiple stem templates for verbal words. However, all variants have a single representation template. The major-ity of words in the language are generated from v roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivatio words from verbal roots usually / and /s k r the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in is the lingua franca and the most literary language serving as a me-in the education system of the country for a long period. Amharic abet and has 34 base characters along with modifications on the re-acters. The alphabet is conveniently written in a tabular format of first column represents the basic form with vowel ኧ /ə/ and the other t modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ example, the base character በ /bə/ has the following modifications: ቡ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface orrows some punctuation marks such as '?' and '!' from Latin alpha-pic alphabet has numeral system, the Arabic numeral system is rather ed by Amharic. logy omplex morphology where many words could be generated through rivational processes from other word forms. Many surface forms of ed from a base form through complex affixation, reduplication, and igitation. Amharic words can be marked for a number of functions. b can be marked for a combination of person, case, gender, number, ood. An Amharic word might take up to four prefixes and five suf-xample, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural er-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands ner-ated from an Amharic root or its stems by changing the shape of or root, inserting vowels between root radicals, reduplicating one of e stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are plates for verbal words. However, all variants have a single root late. The major-ity of words in the language are generated from verbal tives, and ad-verbs can be derived from verbal roots. The derivation of roots usually / are derived from the verbal roots --/n-b-r/, --/l-m-d/ and --/s-k-r/, respectively. The patterns of these stem formations from the roots are ----/nestimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly s Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spo Ethiopia, Amharic is the lingua franca and the most literary language serving as dium of instruction in the education system of the country for a long period. Am uses Ethiopic alphabet and has 34 base characters along with modifications on t spective base characters. The alphabet is conveniently written in a tabular form seven columns. The first column represents the basic form with vowel ኧ /ə/ and the six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modificatio /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized char such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also it punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (p colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin a bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated th inflectional and derivational processes from other word forms. Many surface for words can be formed from a base form through complex affixation, reduplication Semitic stem interdigitation. Amharic words can be marked for a number of func For example, a verb can be marked for a combination of person, case, gender, nu tense, aspect, and mood. An Amharic word might take up to four prefixes and fiv fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨn constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixe ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thou of words can be gener-ated from an Amharic root or its stems by changing the sh characters in a stem or root, inserting vowels between root radicals, reduplicating the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. The multiple stem templates for verbal words. However, all variants have a singl representation template. The major-ity of words in the language are generated from roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivat words from verbal roots usually -g--restimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most comm Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages a Ethiopia, Amharic is the lingua franca and the most literary language serv dium of instruction in the education system of the country for a long peri uses Ethiopic alphabet and has 34 base characters along with modificatio spective base characters. The alphabet is conveniently written in a tabul seven columns. The first column represents the basic form with vowel ኧ /ə/ six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following mod /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialize such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon) colon), etc. It also borrows some punctuation marks such as '?' and '!' from bet. Although Ethiopic alphabet has numeral system, the Arabic numeral sys most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be gener inflectional and derivational processes from other word forms. Many surf words can be formed from a base form through complex affixation, redup Semitic stem interdigitation. Amharic words can be marked for a number For example, a verb can be marked for a combination of person, case, gen tense, aspect, and mood. An Amharic word might take up to four prefixes fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwa constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negati causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third p object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/ of words can be gener-ated from an Amharic root or its stems by changing characters in a stem or root, inserting vowels between root radicals, redupli the characters of the stem or word itself, and by adding affixes on stems [2 multiple stem templates for verbal words. However, all variants have a representation template. The major-ity of words in the language are generated roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The words from verbal roots usually /, ----/l-a-m--d-Amharic is the working language of the government of Ethiopia currently having an ated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken itic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in opia, Amharic is the lingua franca and the most literary language serving as a me-of instruction in the education system of the country for a long period. Amharic Ethiopic alphabet and has 34 base characters along with modifications on the re-tive base characters. The alphabet is conveniently written in a tabular format of n columns. The first column represents the basic form with vowel ኧ /ə/ and the other rders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface n), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather t commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through ctional and derivational processes from other word forms. Many surface forms of ds can be formed from a base form through complex affixation, reduplication, and itic stem interdigitation. Amharic words can be marked for a number of functions. example, a verb can be marked for a combination of person, case, gender, number, e, aspect, and mood. An Amharic word might take up to four prefixes and five suf-s [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is tructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / rst person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural ct marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands ords can be gener-ated from an Amharic root or its stems by changing the shape of acters in a stem or root, inserting vowels between root radicals, reduplicating one of characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are tiple stem templates for verbal words. However, all variants have a single root esentation template. The major-ity of words in the language are generated from verbal s. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of ds from verbal roots usually /, and ----/s--k--r-Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually /, respectively. Here /n/, /g/, /r/, /l/, /m/, /d/, /s/, /k/ and /r/ are consonants (C) whereas , , and are vowels (V). Depending on the types of verbs, stems are produced based on template structures in various forms such as perfective, imperfective, jussive, imperative, etc. [START_REF] Yifru | Morphology-Based Language Modeling for Amharic[END_REF]. For example, the template structures of tri-radicals verb types is presented in Table 2. The rest of this paper is organized as follows. Section 2 describes Amharic language ts morphology. Section 3 discusses related work. In Section 4, we present the pro-Amharic IR system architecture along with various options to represent Amharic ments and queries. Section 5 presents the evaluation framework of the proposed aric adhoc retrieval system including the presentation of the resources and corpora, imental setup, and experimental results. In Section 6, we present our conclusion ut forward further research directions.

haric Language mharic Writing System

Amharic is the working language of the government of Ethiopia currently having an ated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken tic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in pia, Amharic is the lingua franca and the most literary language serving as a me-of instruction in the education system of the country for a long period. Amharic Ethiopic alphabet and has 34 base characters along with modifications on the re-ive base characters. The alphabet is conveniently written in a tabular format of columns. The first column represents the basic form with vowel ኧ /ə/ and the other ders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ nd ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own tuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface ), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-lthough Ethiopic alphabet has numeral system, the Arabic numeral system is rather commonly used by Amharic.

mharic Morphology

Amharic has complex morphology where many words could be generated through tional and derivational processes from other word forms. Many surface forms of s can be formed from a base form through complex affixation, reduplication, and tic stem interdigitation. Amharic words can be marked for a number of functions. xample, a verb can be marked for a combination of person, case, gender, number, , aspect, and mood. An Amharic word might take up to four prefixes and five suf- [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ tive/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / st person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural t marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands rds can be gener-ated from an Amharic root or its stems by changing the shape of cters in a stem or root, inserting vowels between root radicals, reduplicating one of haracters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are ple stem templates for verbal words. However, all variants have a single root sentation template. The major-ity of words in the language are generated from verbal . Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of s from verbal roots usually / CVCVC /f l g and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually / CVCVC /mar k and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually / CVCVC Imperfect /s b a and compiled stopwords list; and (2) to design Amharic IR system by investi-the optimal representation of documents and queries considering both root-based m-based text representations. e rest of this paper is organized as follows. Section 2 describes Amharic language morphology. Section 3 discusses related work. In Section 4, we present the pro-Amharic IR system architecture along with various options to represent Amharic ents and queries. Section 5 presents the evaluation framework of the proposed ic adhoc retrieval system including the presentation of the resources and corpora, ental setup, and experimental results. In Section 6, we present our conclusion t forward further research directions. aric Language haric Writing System mharic is the working language of the government of Ethiopia currently having an ted population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in ia, Amharic is the lingua franca and the most literary language serving as a me-f instruction in the education system of the country for a long period. Amharic thiopic alphabet and has 34 base characters along with modifications on the re-e base characters. The alphabet is conveniently written in a tabular format of olumns. The first column represents the basic form with vowel ኧ /ə/ and the other ers represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters s ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-though Ethiopic alphabet has numeral system, the Arabic numeral system is rather ommonly used by Amharic.

haric Morphology mharic has complex morphology where many words could be generated through onal and derivational processes from other word forms. Many surface forms of can be formed from a base form through complex affixation, reduplication, and stem interdigitation. Amharic words can be marked for a number of functions. mple, a verb can be marked for a combination of person, case, gender, number, spect, and mood. An Amharic word might take up to four prefixes and five suf- [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is cted from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ve/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands ds can be gener-ated from an Amharic root or its stems by changing the shape of ers in a stem or root, inserting vowels between root radicals, reduplicating one of racters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are le stem templates for verbal words. However, all variants have a single root ntation template. The major-ity of words in the language are generated from verbal ouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of from verbal roots usually r ra and compiled stopwords list; and (2) to design Amharic IR system by investi-g the optimal representation of documents and queries considering both root-based tem-based text representations. he rest of this paper is organized as follows. Section 2 describes Amharic language ts morphology. Section 3 discusses related work. In Section 4, we present the pro-Amharic IR system architecture along with various options to represent Amharic ments and queries. Section 5 presents the evaluation framework of the proposed aric adhoc retrieval system including the presentation of the resources and corpora, imental setup, and experimental results. In Section 6, we present our conclusion ut forward further research directions. haric Language mharic Writing System mharic is the working language of the government of Ethiopia currently having an ated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken ic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in pia, Amharic is the lingua franca and the most literary language serving as a me-of instruction in the education system of the country for a long period. Amharic Ethiopic alphabet and has 34 base characters along with modifications on the re-ive base characters. The alphabet is conveniently written in a tabular format of columns. The first column represents the basic form with vowel ኧ /ə/ and the other ders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ nd ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own tuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface ), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-lthough Ethiopic alphabet has numeral system, the Arabic numeral system is rather commonly used by Amharic.

mharic Morphology mharic has complex morphology where many words could be generated through tional and derivational processes from other word forms. Many surface forms of s can be formed from a base form through complex affixation, reduplication, and ic stem interdigitation. Amharic words can be marked for a number of functions. xample, a verb can be marked for a combination of person, case, gender, number, , aspect, and mood. An Amharic word might take up to four prefixes and five suf- [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ tive/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / st person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural t marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands rds can be gener-ated from an Amharic root or its stems by changing the shape of cters in a stem or root, inserting vowels between root radicals, reduplicating one of aracters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are ple stem templates for verbal words. However, all variants have a single root sentation template. The major-ity of words in the language are generated from verbal Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of s from verbal roots usually / CVCC /f l corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually g corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually / CVCC /mar corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually k corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually rest of this paper is organized as follows. Section 2 describes Amharic language orphology. Section 3 discusses related work. In Section 4, we present the pro-mharic IR system architecture along with various options to represent Amharic ts and queries. Section 5 presents the evaluation framework of the proposed adhoc retrieval system including the presentation of the resources and corpora, ntal setup, and experimental results. In Section 6, we present our conclusion forward further research directions.

ric Language

aric Writing System haric is the working language of the government of Ethiopia currently having an population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken anguage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in , Amharic is the lingua franca and the most literary language serving as a me-instruction in the education system of the country for a long period. Amharic iopic alphabet and has 34 base characters along with modifications on the re-base characters. The alphabet is conveniently written in a tabular format of lumns. The first column represents the basic form with vowel ኧ /ə/ and the other s represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ i/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ions such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface tc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-ough Ethiopic alphabet has numeral system, the Arabic numeral system is rather monly used by Amharic.

aric Morphology haric has complex morphology where many words could be generated through al and derivational processes from other word forms. Many surface forms of n be formed from a base form through complex affixation, reduplication, and tem interdigitation. Amharic words can be marked for a number of functions. ple, a verb can be marked for a combination of person, case, gender, number, pect, and mood. An Amharic word might take up to four prefixes and five suf-8]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ted from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ /, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / erson singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural arker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands can be gener-ated from an Amharic root or its stems by changing the shape of s in a stem or root, inserting vowels between root radicals, reduplicating one of cters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are stem templates for verbal words. However, all variants have a single root tation template. The major-ity of words in the language are generated from verbal uns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of m verbal roots usually b r tools. The objective of this research work is: (1) to promote publicly accessible Am-resources including a standard test collection for IR, morphologically annotated ra and compiled stopwords list; and (2) to design Amharic IR system by investi-g the optimal representation of documents and queries considering both root-based tem-based text representations. he rest of this paper is organized as follows. Section 2 describes Amharic language ts morphology. Section 3 discusses related work. In Section 4, we present the pro-Amharic IR system architecture along with various options to represent Amharic ments and queries. Section 5 presents the evaluation framework of the proposed aric adhoc retrieval system including the presentation of the resources and corpora, imental setup, and experimental results. In Section 6, we present our conclusion ut forward further research directions. haric Language mharic Writing System mharic is the working language of the government of Ethiopia currently having an ated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken ic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in pia, Amharic is the lingua franca and the most literary language serving as a me-of instruction in the education system of the country for a long period. Amharic Ethiopic alphabet and has 34 base characters along with modifications on the re-ive base characters. The alphabet is conveniently written in a tabular format of columns. The first column represents the basic form with vowel ኧ /ə/ and the other ders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ nd ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own tuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface ), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-lthough Ethiopic alphabet has numeral system, the Arabic numeral system is rather commonly used by Amharic.

mharic Morphology mharic has complex morphology where many words could be generated through tional and derivational processes from other word forms. Many surface forms of s can be formed from a base form through complex affixation, reduplication, and ic stem interdigitation. Amharic words can be marked for a number of functions. xample, a verb can be marked for a combination of person, case, gender, number, , aspect, and mood. An Amharic word might take up to four prefixes and five suf- [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ tive/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / st person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural t marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands rds can be gener-ated from an Amharic root or its stems by changing the shape of cters in a stem or root, inserting vowels between root radicals, reduplicating one of aracters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are ple stem templates for verbal words. However, all variants have a single root sentation template. The major-ity of words in the language are generated from verbal Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of s from verbal roots usually / CCVC /f l NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

2.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually g NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

2.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually

/ CVCC /mar
NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

2.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually k NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

2.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually / CVCC Gerund /s b lt to create annotated corpus automatically. Moreover, there is lack of standard ce collection making it a major impediment to the development of Amharic IR and ols. The objective of this research work is: (1) to promote publicly accessible Am-esources including a standard test collection for IR, morphologically annotated a and compiled stopwords list; and (2) to design Amharic IR system by investi-the optimal representation of documents and queries considering both root-based m-based text representations. e rest of this paper is organized as follows. Section 2 describes Amharic language morphology. Section 3 discusses related work. In Section 4, we present the pro-Amharic IR system architecture along with various options to represent Amharic ents and queries. Section 5 presents the evaluation framework of the proposed ic adhoc retrieval system including the presentation of the resources and corpora, ental setup, and experimental results. In Section 6, we present our conclusion t forward further research directions. aric Language haric Writing System mharic is the working language of the government of Ethiopia currently having an ted population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in ia, Amharic is the lingua franca and the most literary language serving as a me-f instruction in the education system of the country for a long period. Amharic thiopic alphabet and has 34 base characters along with modifications on the re-e base characters. The alphabet is conveniently written in a tabular format of olumns. The first column represents the basic form with vowel ኧ /ə/ and the other ers represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters s ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-though Ethiopic alphabet has numeral system, the Arabic numeral system is rather ommonly used by Amharic.

haric Morphology mharic has complex morphology where many words could be generated through onal and derivational processes from other word forms. Many surface forms of can be formed from a base form through complex affixation, reduplication, and stem interdigitation. Amharic words can be marked for a number of functions. mple, a verb can be marked for a combination of person, case, gender, number, spect, and mood. An Amharic word might take up to four prefixes and five suf- [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is cted from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ve/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands ds can be gener-ated from an Amharic root or its stems by changing the shape of ers in a stem or root, inserting vowels between root radicals, reduplicating one of racters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are le stem templates for verbal words. However, all variants have a single root ntation template. The major-ity of words in the language are generated from verbal ouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of from verbal roots usually r ult to create annotated corpus automatically. Moreover, there is lack of standard nce collection making it a major impediment to the development of Amharic IR and tools. The objective of this research work is: (1) to promote publicly accessible Am-resources including a standard test collection for IR, morphologically annotated ra and compiled stopwords list; and (2) to design Amharic IR system by investi-g the optimal representation of documents and queries considering both root-based tem-based text representations. he rest of this paper is organized as follows. Section 2 describes Amharic language ts morphology. Section 3 discusses related work. In Section 4, we present the pro-Amharic IR system architecture along with various options to represent Amharic ments and queries. Section 5 presents the evaluation framework of the proposed aric adhoc retrieval system including the presentation of the resources and corpora, imental setup, and experimental results. In Section 6, we present our conclusion ut forward further research directions. haric Language mharic Writing System mharic is the working language of the government of Ethiopia currently having an ated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken ic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in pia, Amharic is the lingua franca and the most literary language serving as a me-of instruction in the education system of the country for a long period. Amharic Ethiopic alphabet and has 34 base characters along with modifications on the re-ive base characters. The alphabet is conveniently written in a tabular format of columns. The first column represents the basic form with vowel ኧ /ə/ and the other ders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ nd ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own tuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface ), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-lthough Ethiopic alphabet has numeral system, the Arabic numeral system is rather commonly used by Amharic.

mharic Morphology mharic has complex morphology where many words could be generated through tional and derivational processes from other word forms. Many surface forms of s can be formed from a base form through complex affixation, reduplication, and ic stem interdigitation. Amharic words can be marked for a number of functions. xample, a verb can be marked for a combination of person, case, gender, number, , aspect, and mood. An Amharic word might take up to four prefixes and five suf- [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ tive/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / st person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural t marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands rds can be gener-ated from an Amharic root or its stems by changing the shape of cters in a stem or root, inserting vowels between root radicals, reduplicating one of aracters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are ple stem templates for verbal words. However, all variants have a single root sentation template. The major-ity of words in the language are generated from verbal Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of s from verbal roots usually / CVCC /f l difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

2.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually g difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

2.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually / CVCC /mar difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

2.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually k difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

2.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually

/ CVCC Infinitive /s
scope. The unavailability of full-fledged low-level Amharic NLP tools makes it to create annotated corpus automatically. Moreover, there is lack of standard collection making it a major impediment to the development of Amharic IR and ls. The objective of this research work is: (1) to promote publicly accessible Am-ources including a standard test collection for IR, morphologically annotated and compiled stopwords list; and (2) to design Amharic IR system by investi-e optimal representation of documents and queries considering both root-based -based text representations. rest of this paper is organized as follows. Section 2 describes Amharic language orphology. Section 3 discusses related work. In Section 4, we present the pro-mharic IR system architecture along with various options to represent Amharic ts and queries. Section 5 presents the evaluation framework of the proposed adhoc retrieval system including the presentation of the resources and corpora, ntal setup, and experimental results. In Section 6, we present our conclusion forward further research directions.

ric Language

aric Writing System haric is the working language of the government of Ethiopia currently having an population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken anguage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in , Amharic is the lingua franca and the most literary language serving as a me-instruction in the education system of the country for a long period. Amharic iopic alphabet and has 34 base characters along with modifications on the re-base characters. The alphabet is conveniently written in a tabular format of lumns. The first column represents the basic form with vowel ኧ /ə/ and the other s represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ i/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ions such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface tc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-ough Ethiopic alphabet has numeral system, the Arabic numeral system is rather monly used by Amharic.

aric Morphology haric has complex morphology where many words could be generated through al and derivational processes from other word forms. Many surface forms of n be formed from a base form through complex affixation, reduplication, and tem interdigitation. Amharic words can be marked for a number of functions. ple, a verb can be marked for a combination of person, case, gender, number, pect, and mood. An Amharic word might take up to four prefixes and five suf-8]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ted from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ /, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / erson singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural arker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands can be gener-ated from an Amharic root or its stems by changing the shape of s in a stem or root, inserting vowels between root radicals, reduplicating one of cters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are stem templates for verbal words. However, all variants have a single root tation template. The major-ity of words in the language are generated from verbal uns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of m verbal roots usually b r d in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it ult to create annotated corpus automatically. Moreover, there is lack of standard nce collection making it a major impediment to the development of Amharic IR and tools. The objective of this research work is: (1) to promote publicly accessible Am-resources including a standard test collection for IR, morphologically annotated ra and compiled stopwords list; and (2) to design Amharic IR system by investi-g the optimal representation of documents and queries considering both root-based tem-based text representations. he rest of this paper is organized as follows. Section 2 describes Amharic language ts morphology. Section 3 discusses related work. In Section 4, we present the pro-Amharic IR system architecture along with various options to represent Amharic ments and queries. Section 5 presents the evaluation framework of the proposed aric adhoc retrieval system including the presentation of the resources and corpora, imental setup, and experimental results. In Section 6, we present our conclusion ut forward further research directions. haric Language mharic Writing System mharic is the working language of the government of Ethiopia currently having an ated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken ic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in pia, Amharic is the lingua franca and the most literary language serving as a me-of instruction in the education system of the country for a long period. Amharic Ethiopic alphabet and has 34 base characters along with modifications on the re-ive base characters. The alphabet is conveniently written in a tabular format of columns. The first column represents the basic form with vowel ኧ /ə/ and the other ders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ nd ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own tuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface ), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-lthough Ethiopic alphabet has numeral system, the Arabic numeral system is rather commonly used by Amharic.

mharic Morphology mharic has complex morphology where many words could be generated through tional and derivational processes from other word forms. Many surface forms of s can be formed from a base form through complex affixation, reduplication, and ic stem interdigitation. Amharic words can be marked for a number of functions. xample, a verb can be marked for a combination of person, case, gender, number, , aspect, and mood. An Amharic word might take up to four prefixes and five suf- [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ tive/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / st person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural t marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands rds can be gener-ated from an Amharic root or its stems by changing the shape of cters in a stem or root, inserting vowels between root radicals, reduplicating one of aracters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are ple stem templates for verbal words. However, all variants have a single root sentation template. The major-ity of words in the language are generated from verbal Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of s from verbal roots usually

/ CCVC /f
limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually l g limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually / CVCVC /mar k limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually /, it is possible to generate the following words:

/n g r FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually kwat Appl. Sci. 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

ʃ

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually 'I told them'/, /t n g r t The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat The rest of this paper is organized as follows. Section 2 describes Amharic lang and its morphology. Section 3 discusses related work. In Section 4, we present the posed Amharic IR system architecture along with various options to represent Am documents and queries. Section 5 presents the evaluation framework of the prop Amharic adhoc retrieval system including the presentation of the resources and cor experimental setup, and experimental results. In Section 6, we present our concl and put forward further research directions.

ʃ

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently havi estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly sp Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spok Ethiopia, Amharic is the lingua franca and the most literary language serving as a dium of instruction in the education system of the country for a long period. Am uses Ethiopic alphabet and has 34 base characters along with modifications on th spective base characters. The alphabet is conveniently written in a tabular form seven columns. The first column represents the basic form with vowel ኧ /ə/ and the six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modificatio /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized chara such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (pr colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin a bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is r most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated thr inflectional and derivational processes from other word forms. Many surface form words can be formed from a base form through complex affixation, reduplication Semitic stem interdigitation. Amharic words can be marked for a number of func For example, a verb can be marked for a combination of person, case, gender, num tense, aspect, and mood. An Amharic word might take up to four prefixes and fiv fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨn constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixe ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person p object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thou of words can be gener-ated from an Amharic root or its stems by changing the sha characters in a stem or root, inserting vowels between root radicals, reduplicating o the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. Ther multiple stem templates for verbal words. However, all variants have a single representation template. The major-ity of words in the language are generated from v roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivati words from verbal roots usually 'she has been told'/, /n g r FOR PEER REVIEW 4 of 29 involves stem formation followed by word formation. Amharic roots are the base of stems which in turn are the base of many surface forms of words (see Table 1). Amharic verbal stems are formed from verbal roots by inserting vowels between radicals (consonants). For example, the verbal stems ንገር /nɨgərɨ/, ላመድ /lamədɨ/ and ሰከር /səkərɨ/ are derived from the verbal roots ን-ግ-ር /n-b-r/, ል-ም-ድ /l-m-d/ and ስ-ክ-ር /s-k-r/, respectively. The patterns of these stem formations from the roots are ን-እ-ግ-ኧ-ር /n-ɨ-g-ə-r-ɨ/, ል-ኣ-ም-ኧ-ድ /l-a-m-ə-d-ɨ/, and ሰ-ኧ-ከ-ኧ-ር /s-ə-k-ə-r-ɨ/, respectively. Here ን /n/, ግ /g/, ር /r/, ል /l/, ም /m/, ድ /d/, ስ /s/, ክ /k/ and ር /r/ are consonants (C) whereas እ, ኧ, and ኣ are vowels (V).

Depending on the types of verbs, stems are produced based on template structures in various forms such as perfective, imperfective, jussive, imperative, etc. [START_REF] Yifru | Morphology-Based Language Modeling for Amharic[END_REF]. For example, VIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually Appl. Sci. 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

ʃ

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually w Appl. Sci. 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually 'you told him'/, etc. Words generated from stems could have both prefixes and suffixes. For example, the word /s rest of this paper is organized as follows. Section 2 describes Amharic language orphology. Section 3 discusses related work. In Section 4, we present the pro-mharic IR system architecture along with various options to represent Amharic nts and queries. Section 5 presents the evaluation framework of the proposed adhoc retrieval system including the presentation of the resources and corpora, ental setup, and experimental results. In Section 6, we present our conclusion forward further research directions. ric Language aric Writing System haric is the working language of the government of Ethiopia currently having an d population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken anguage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in , Amharic is the lingua franca and the most literary language serving as a me-instruction in the education system of the country for a long period. Amharic iopic alphabet and has 34 base characters along with modifications on the re-base characters. The alphabet is conveniently written in a tabular format of lumns. The first column represents the basic form with vowel ኧ /ə/ and the other rs represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own tions such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface tc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-ough Ethiopic alphabet has numeral system, the Arabic numeral system is rather monly used by Amharic.

aric Morphology haric has complex morphology where many words could be generated through nal and derivational processes from other word forms. Many surface forms of an be formed from a base form through complex affixation, reduplication, and stem interdigitation. Amharic words can be marked for a number of functions.

ple, a verb can be marked for a combination of person, case, gender, number, pect, and mood. An Amharic word might take up to four prefixes and five suf-8]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ted from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ e/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / erson singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural arker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands s can be gener-ated from an Amharic root or its stems by changing the shape of rs in a stem or root, inserting vowels between root radicals, reduplicating one of acters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are stem templates for verbal words. However, all variants have a single root tation template. The major-ity of words in the language are generated from verbal ouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of om verbal roots usually lal 3 of 29 d in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it ult to create annotated corpus automatically. Moreover, there is lack of standard nce collection making it a major impediment to the development of Amharic IR and tools. The objective of this research work is: (1) to promote publicly accessible Am-resources including a standard test collection for IR, morphologically annotated ra and compiled stopwords list; and (2) to design Amharic IR system by investi-g the optimal representation of documents and queries considering both root-based tem-based text representations. he rest of this paper is organized as follows. Section 2 describes Amharic language ts morphology. Section 3 discusses related work. In Section 4, we present the pro-Amharic IR system architecture along with various options to represent Amharic ments and queries. Section 5 presents the evaluation framework of the proposed aric adhoc retrieval system including the presentation of the resources and corpora, imental setup, and experimental results. In Section 6, we present our conclusion ut forward further research directions. haric Language mharic Writing System mharic is the working language of the government of Ethiopia currently having an ated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken tic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in pia, Amharic is the lingua franca and the most literary language serving as a me-of instruction in the education system of the country for a long period. Amharic Ethiopic alphabet and has 34 base characters along with modifications on the re-ive base characters. The alphabet is conveniently written in a tabular format of columns. The first column represents the basic form with vowel ኧ /ə/ and the other ders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ nd ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own tuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface ), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-lthough Ethiopic alphabet has numeral system, the Arabic numeral system is rather commonly used by Amharic.

mharic Morphology mharic has complex morphology where many words could be generated through tional and derivational processes from other word forms. Many surface forms of s can be formed from a base form through complex affixation, reduplication, and tic stem interdigitation. Amharic words can be marked for a number of functions. xample, a verb can be marked for a combination of person, case, gender, number, , aspect, and mood. An Amharic word might take up to four prefixes and five suf- [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ tive/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / st person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural t marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands rds can be gener-ated from an Amharic root or its stems by changing the shape of cters in a stem or root, inserting vowels between root radicals, reduplicating one of haracters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are ple stem templates for verbal words. However, all variants have a single root sentation template. The major-ity of words in the language are generated from verbal . Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of s from verbal roots usually t d w l lat 022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

ʃ

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually na/ has three prefixes ( /s Appl. Sci. 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually l preposition/, / Appl. Sci. 2022, 12, x FOR PEER REVIEW 3 of limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes difficult to create annotated corpus automatically. Moreover, there is lack of standa reference collection making it a major impediment to the development of Amharic IR an NLP tools. The objective of this research work is: (1) to promote publicly accessible Am haric resources including a standard test collection for IR, morphologically annotate corpora and compiled stopwords list; and (2) to design Amharic IR system by inves gating the optimal representation of documents and queries considering both root-base and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic langua and its morphology. Section 3 discusses related work. In Section 4, we present the pr posed Amharic IR system architecture along with various options to represent Amhar documents and queries. Section 5 presents the evaluation framework of the propose Amharic adhoc retrieval system including the presentation of the resources and corpor experimental setup, and experimental results. In Section 6, we present our conclusio and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having a estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spok Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken Ethiopia, Amharic is the lingua franca and the most literary language serving as a m dium of instruction in the education system of the country for a long period. Amhar uses Ethiopic alphabet and has 34 base characters along with modifications on the r spective base characters. The alphabet is conveniently written in a tabular format seven columns.

The first column represents the basic form with vowel ኧ /ə/ and t other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the followin modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there a labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. T language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arab numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated throug inflectional and derivational processes from other word forms. Many surface forms words can be formed from a base form through complex affixation, reduplication, an Semitic stem interdigitation. Amharic words can be marked for a number of function For example, a verb can be marked for a combination of person, case, gender, numbe tense, aspect, and mood. An Amharic word might take up to four prefixes and five su l Appl. Sci. 2022, 12, x FOR PEER REVIEW limited in scope. The unavailability of full-fledged low-level Amharic NLP difficult to create annotated corpus automatically. Moreover, there is la reference collection making it a major impediment to the development of A NLP tools. The objective of this research work is: (1) to promote publicly a haric resources including a standard test collection for IR, morphologic corpora and compiled stopwords list; and (2) to design Amharic IR syst gating the optimal representation of documents and queries considering b and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Am and its morphology. Section 3 discusses related work. In Section 4, we pr posed Amharic IR system architecture along with various options to repr documents and queries. Section 5 presents the evaluation framework of Amharic adhoc retrieval system including the presentation of the resource experimental setup, and experimental results. In Section 6, we present o and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia curre estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most com Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages Ethiopia, Amharic is the lingua franca and the most literary language se dium of instruction in the education system of the country for a long pe uses Ethiopic alphabet and has 34 base characters along with modificati spective base characters. The alphabet is conveniently written in a tab seven columns. The first column represents the basic form with vowel ኧ /ə six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following m /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labiali such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language ha punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon colon), etc. It also borrows some punctuation marks such as '?' and '!' from bet. Although Ethiopic alphabet has numeral system, the Arabic numeral s most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be gene inflectional and derivational processes from other word forms. Many su words can be formed from a base form through complex affixation, redu Semitic stem interdigitation. Amharic words can be marked for a numbe For example, a verb can be marked for a combination of person, case, ge tense, aspect, and mood. An Amharic word might take up to four prefixe fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkw constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ nega causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and fou ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunctio of words can be gener-ated from an Amharic root or its stems by changin characters in a stem or root, inserting vowels between root radicals, redup the characters of the stem or word itself, and by adding affixes on stems multiple stem templates for verbal words. However, all variants have representation template. The major-ity of words in the language are generat roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually / and four suffixes ( / /, /l 3 of 29 availability of full-fledged low-level Amharic NLP tools makes it tated corpus automatically. Moreover, there is lack of standard ing it a major impediment to the development of Amharic IR and e of this research work is: (1) to promote publicly accessible Am-ng a standard test collection for IR, morphologically annotated stopwords list; and (2) to design Amharic IR system by investi-esentation of documents and queries considering both root-based resentations. er is organized as follows. Section 2 describes Amharic language ction 3 discusses related work. In Section 4, we present the pro-m architecture along with various options to represent Amharic . Section 5 presents the evaluation framework of the proposed system including the presentation of the resources and corpora, d experimental results. In Section 6, we present our conclusion r research directions. tem king language of the government of Ethiopia currently having an f over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in e lingua franca and the most literary language serving as a me-the education system of the country for a long period. Amharic and has 34 base characters along with modifications on the re-s. The alphabet is conveniently written in a tabular format of t column represents the basic form with vowel ኧ /ə/ and the other difications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ple, the base character በ /bə/ has the following modifications: ቡ /, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters a/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface ws some punctuation marks such as '?' and '!' from Latin alpha-lphabet has numeral system, the Arabic numeral system is rather y Amharic. lex morphology where many words could be generated through ional processes from other word forms. Many surface forms of rom a base form through complex affixation, reduplication, and tion. Amharic words can be marked for a number of functions. n be marked for a combination of person, case, gender, number, . An Amharic word might take up to four prefixes and five suf-ple, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ -cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural ctive verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands ated from an Amharic root or its stems by changing the shape of root, inserting vowels between root radicals, reduplicating one of m or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are s for verbal words. However, all variants have a single root . The major-ity of words in the language are generated from verbal , and ad-verbs can be derived from verbal roots. The derivation of usually beneficative/, / 3 of 29 scope. The unavailability of full-fledged low-level Amharic NLP tools makes it o create annotated corpus automatically. Moreover, there is lack of standard collection making it a major impediment to the development of Amharic IR and . The objective of this research work is: (1) to promote publicly accessible Amurces including a standard test collection for IR, morphologically annotated nd compiled stopwords list; and (2) to design Amharic IR system by investioptimal representation of documents and queries considering both root-based based text representations. est of this paper is organized as follows. Section 2 describes Amharic language orphology. Section 3 discusses related work. In Section 4, we present the proharic IR system architecture along with various options to represent Amharic s and queries. Section 5 presents the evaluation framework of the proposed dhoc retrieval system including the presentation of the resources and corpora, tal setup, and experimental results. In Section 6, we present our conclusion rward further research directions. c Language ic Writing System aric is the working language of the government of Ethiopia currently having an population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken nguage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Amharic is the lingua franca and the most literary language serving as a menstruction in the education system of the country for a long period. Amharic pic alphabet and has 34 base characters along with modifications on the rease characters. The alphabet is conveniently written in a tabular format of umns.

The first column represents the basic form with vowel ኧ /ə/ and the rders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / , እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following ions: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), , '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' m Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic ystem is rather most commonly used by Amharic.

ic Morphology aric has complex morphology where many words could be generated through l and derivational processes from other word forms. Many surface forms of be formed from a base form through complex affixation, reduplication, and em interdigitation. Amharic words can be marked for a number of functions. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

ʃ

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually [3rd person, plural]/, /na conjunction/). Many words are also formed through inflectional process. Amharic nouns and adjectives are inflected with number, person, gender, definiteness, etc. to form many words in surface forms. Some Amharic functional words such as prepositions, conjunctions, etc. also undergo morphological process to form variants. They exist either by merging with each other or by affixation with other words. For example, from the word /lela 'other'/ variants that could be generated include /lelaw t The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

ʃ

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root /, /j lela/, /k lela/, /b lela/, /j lelot 3 of 29 cope. The unavailability of full-fledged low-level Amharic NLP tools makes it create annotated corpus automatically. Moreover, there is lack of standard llection making it a major impediment to the development of Amharic IR and The objective of this research work is: (1) to promote publicly accessible Am-rces including a standard test collection for IR, morphologically annotated d compiled stopwords list; and (2) to design Amharic IR system by investi-ptimal representation of documents and queries considering both root-based ased text representations. st of this paper is organized as follows. Section 2 describes Amharic language rphology. Section 3 discusses related work. In Section 4, we present the pro-aric IR system architecture along with various options to represent Amharic and queries. Section 5 presents the evaluation framework of the proposed hoc retrieval system including the presentation of the resources and corpora, al setup, and experimental results. In Section 6, we present our conclusion ward further research directions.

Language c Writing System

ric is the working language of the government of Ethiopia currently having an opulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken guage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in mharic is the lingua franca and the most literary language serving as a me-struction in the education system of the country for a long period. Amharic ic alphabet and has 34 base characters along with modifications on the re-se characters. The alphabet is conveniently written in a tabular format of ns. The first column represents the basic form with vowel ኧ /ə/ and the other epresent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ o/. For example, the base character በ /bə/ has the following modifications: ቡ ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ns such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface It also borrows some punctuation marks such as '?' and '!' from Latin alpha-gh Ethiopic alphabet has numeral system, the Arabic numeral system is rather only used by Amharic.

c Morphology ric has complex morphology where many words could be generated through and derivational processes from other word forms. Many surface forms of be formed from a base form through complex affixation, reduplication, and m interdigitation. Amharic words can be marked for a number of functions. le, a verb can be marked for a combination of person, case, gender, number, ct, and mood. An Amharic word might take up to four prefixes and five suf-or example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first ular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of be gener-ated from an Amharic root or its stems by changing the shape of n a stem or root, inserting vowels between root radicals, reduplicating one of ers of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are em templates for verbal words. However, all variants have a single root

of 29

The unavailability of full-fledged low-level Amharic NLP tools makes it annotated corpus automatically. Moreover, there is lack of standard n making it a major impediment to the development of Amharic IR and bjective of this research work is: (1) to promote publicly accessible Am-ncluding a standard test collection for IR, morphologically annotated piled stopwords list; and (2) to design Amharic IR system by investi-l representation of documents and queries considering both root-based ext representations.

is paper is organized as follows. Section 2 describes Amharic language gy. Section 3 discusses related work. In Section 4, we present the pro-R system architecture along with various options to represent Amharic ueries. Section 5 presents the evaluation framework of the proposed trieval system including the presentation of the resources and corpora, p, and experimental results. In Section 6, we present our conclusion further research directions.

age ng System

he working language of the government of Ethiopia currently having an tion of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in ic is the lingua franca and the most literary language serving as a me-on in the education system of the country for a long period. Amharic habet and has 34 base characters along with modifications on the re-aracters. The alphabet is conveniently written in a tabular format of he first column represents the basic form with vowel ኧ /ə/ and the other nt modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ r example, the base character በ /bə/ has the following modifications: ቡ , ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own h as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface borrows some punctuation marks such as '?' and '!' from Latin alpha-iopic alphabet has numeral system, the Arabic numeral system is rather sed by Amharic. hology complex morphology where many words could be generated through erivational processes from other word forms. Many surface forms of med from a base form through complex affixation, reduplication, and rdigitation. Amharic words can be marked for a number of functions. erb can be marked for a combination of person, case, gender, number, mood. An Amharic word might take up to four prefixes and five suf-example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ecipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / gular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands gener-ated from an Amharic root or its stems by changing the shape of m or root, inserting vowels between root radicals, reduplicating one of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are /, /s 3 of 29 ited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it fficult to create annotated corpus automatically. Moreover, there is lack of standard ference collection making it a major impediment to the development of Amharic IR and LP tools. The objective of this research work is: (1) to promote publicly accessible Am-ric resources including a standard test collection for IR, morphologically annotated rpora and compiled stopwords list; and (2) to design Amharic IR system by investi-ting the optimal representation of documents and queries considering both root-based d stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language d its morphology. Section 3 discusses related work. In Section 4, we present the pro-sed Amharic IR system architecture along with various options to represent Amharic cuments and queries. Section 5 presents the evaluation framework of the proposed mharic adhoc retrieval system including the presentation of the resources and corpora, perimental setup, and experimental results. In Section 6, we present our conclusion d put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an timated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken mitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in hiopia, Amharic is the lingua franca and the most literary language serving as a me-um of instruction in the education system of the country for a long period. Amharic es Ethiopic alphabet and has 34 base characters along with modifications on the re-ective base characters. The alphabet is conveniently written in a tabular format of ven columns. The first column represents the basic form with vowel ኧ /ə/ and the other x orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ u/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters ch as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own nctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface lon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-t. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather ost commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through flectional and derivational processes from other word forms. Many surface forms of ords can be formed from a base form through complex affixation, reduplication, and mitic stem interdigitation. Amharic words can be marked for a number of functions. r example, a verb can be marked for a combination of person, case, gender, number, nse, aspect, and mood. An Amharic word might take up to four prefixes and five suf-xes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is nstructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ usative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural ject marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands words can be gener-ated from an Amharic root or its stems by changing the shape of aracters in a stem or root, inserting vowels between root radicals, reduplicating one of e characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are l lelot , 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

ʃ

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

ʃ

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are n R PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are /, etc. In general, the formation of thousands of words, especially from verbal roots makes the analysis, annotation and tagging of Amharic text a difficult task. This level of morphological complexity has significantly contributed to the difficulty of producing linguistic resources and NLP applications for Amharic. Therefore, the morphological structure of Amharic is an important issue while developing Amharic NLP tools, resources and applications.

Related Work

Semitic languages are known to pose unique challenges in the development of NLP applications due to their complex morphologies. These challenges are propagated to the development of IR systems since the effectiveness of IR systems depends on the availability of various NLP tools and resources. In this section, we discuss the techniques and NLP resources used to develop IR systems for Semitic languages in general.

Arabic is the largest of the Semitic language family. Arabic IR systems have relatively a long history [START_REF] Larkey | Light stemming for Arabic information retrieval[END_REF][START_REF] Ambati | Multilingual information access: Information Retrieval and Translation in a Digital Library[END_REF][START_REF] Darwish | Arabic information retrieval[END_REF]. Musaid [START_REF] Musaid | Arabic Information Retrieval System-Based on Morphological Analysis (AIRSMA): A Comparative Study of Word, Stem, Root and Morpho-Semantic Methods[END_REF] investigated the effectiveness of word-based, stembased, and root-based representation of documents and queries. The word-based and stem-based text representations miss relevant documents while root-based representation retrieves non-relevant documents. Moukdad [START_REF] Moukdad | Comparison of Root and Stemming Techniques for the Retrieval of Arabic Documents[END_REF] compared the effects of stem and root on Arabic IR. The results of their experiments indicate that the use of stem is more effective than root. Larkey et al. [START_REF] Larkey | Light stemming for Arabic information retrieval[END_REF] investigated the effects of light stemming (removal of prefix and suffix) on Arabic IR. A comparison was made between stem-based and root-based retrieval. The finding indicates that light stemmer outperforms root analyzer and other stemmers which are based on detailed morphological analysis. Abdusalam [START_REF] Abdusalam | Effective Retrieval Techniques for Arabic Text[END_REF] presented an Arabic text retrieval technique using lexicon-based light stemming. The study evaluated the effectiveness of lexicon-based light stemming, Arabic patterns, root, expanding query and filtering foreign words using n-grams on TREC 2001 test collection. According to the results, the preprocessing techniques such as normalization, stopword removal and lightstemming improve retrieval results whereas n-grams and roots decrease the performance. Al-Hadid et al. [START_REF] Al-Hadid | Arabic information retrieval system using the neural network model[END_REF] developed a neural network-based model where documents and queries are represented using stems and their similarity is computed using cosine similarity. The lexicon-based stemming and the relevance feedback approaches perform better than lightstemming approach alone. Ali et al. [START_REF] Alnaied | An intelligent use of stemmer and morphology analysis for Arabic information retrieval[END_REF] investigated the effect of morphological analysis on Arabic IR. A rule-based stemmer was used to extract the root/stem of words to be used as indexing and searching terms. The results showed slight improvement on IR effectiveness due to the stemmer.

Hebrew is another Semitic language, spoken mainly in Israel. Carmel [START_REF] Carmel | Morphological disambiguation for Hebrew search systems[END_REF] presented a morphological disambiguation tool based on a statistical approach that takes advantage of an existing morphological analyzer. The approach is context-free and was used for query analysis and linguistic indexing of text documents. Instead of words, the morphological patterns were used for disambiguation. The statistical morphological disambiguator returns only the best base form(s), or lemma(s). It makes the decisions of the most likely set of analyses based on the frequency of the morphological patterns associated with the analyses of the input word. The disambiguator was tested by integrating with the Hebrew search engine. It conflates all inflectional forms and the performance of the search engine increased. Ornan [START_REF] Ornan | A morphological, syntactic and semantic search engine for Hebrew texts[END_REF] designed Hebrew search engine by applying a rule-based morphological analysis. The design of the search engine considers the construction of morphological, syntactic and semantic analyzers. The search engine eliminates words unsuited both to the syntax and the semantics of a sentence.

Although Amharic is significantly used in Ethiopia, the status of IR system development for the language is relatively at rudimentary level. Alemayehu and Willett [START_REF] Alemayehu | The effectiveness of stemming for information retrieval in Amharic. Program Electron[END_REF] studied the retrieval effectiveness of word-based, stem-based, and root-based text representations on Amharic language. The experiments were carried out by running 40 queries on 548 documents using OKAPI system and the study concludes that stem-based retrieval is slightly better than root-based. Mindaye et al. [START_REF] Mindaye | Design and implementation of Amharic search engine[END_REF] developed an Amharic search engine using stems. The system was tested with 11 queries on 75 news documents. On this small collection, the average precision and recall values they report are 0.65 and 0.95, respectively, using OR operator in between query terms, and 0.99 and 0.52, respectively, for AND operator. Argaw et al. [START_REF] Argaw | Dictionary-Based Amharic-French Information Retrieval[END_REF] developed dictionary-based Amharic-English IR system. Documents and queries are represented using bag-of-words. In their work, stopwords are removed using Inverse Document Frequency (IDF) and stopwords list. The average precisions of 0.3615 and 0.4009 were achieved using IDF and stopword list, respectively. Argaw et al. [START_REF] Argaw | Amharic-English information retrieval[END_REF] also have developed dictionary-based Amharic-French IR system with and without word sense discrimination using bag-of-words approach. Word sense discrimination refers to the distinction between different word meanings without sense assignment [START_REF] Chifu | Word sense discrimination in information retrieval: A spectral clustering-based approach[END_REF]. Stemming was applied to remove prefix and suffix. The experiments were conducted on the Swedish Institute of Computer Science (SICS) and Lucene search engines. Stopwords were removed by using IDF. The authors presented that the results are better when using SICS than Lucene. The word sense discrimination performs slightly better than non-discrimination.

The effect of query expansion using word embedding was evaluated in some researches. The impact of query expansion on IR based on NLP tools and Word2Vec embedding algorithms was verified in [START_REF] Aklouche | Query expansion based on NLP and word embedings[END_REF]. Continuous Bag of Word (CBOW) and Skip-gram models were trained on TREC corpus and used to select semantically related terms to the initial query terms. In order to obtain better retrieval result, the two word embedding models were combined with stemming. Okapi BM25 probabilistic weighting scheme with default parameters was used for ranking retrieved documents. The experiment was conducted by running 72 queries. The mean average precision (MAP) 0.1769 and 0.128 are obtained for Skip-gram and CBOW models, respectively. Whereas the Normalized Discount cumulative Gain (NDCG) values 0.4576 and 0.3841 are obtained for skip-gram and CBOW models, respectively. The use of local and global word embedding in query expansion for adhoc IR was studied in [START_REF] Diaz | Query expansion with locally-trained word embeddings[END_REF]. The idea was to evaluate the effect of the local word embedding CBOW and the global word embedding GloVe on query expansion. Various experiments were conducted on TREC12, Wiki, news, web, and robust corpora after stemming using Language Modeling (LM) approach. The result indicates that query expansion using local embedding is better than global embedding for IR. However, the retrieval effectiveness of query expansion using local embedding is poor. Amharic semantic-based IR system was developed using BM25 model [START_REF] Getnet | Amharic information retrieval based on query expansion using semantic vocabulary[END_REF]. Documents and queries were processed by a stemmer. The retrieval effectiveness of the system was evaluated by running 10 queries on 8759 documents and performed an average recall and precision of 0.84 and 0.23, respectively. Hadi et al. [START_REF] Hadi | Word-embedding-based query expansion: Incorporating deep averaging networks in Arabic document retrieval[END_REF] developed Arabic document retrieval system based on word-embedding and prospect-guided as query expansion techniques. The deep averaging network in vector space model, the probabilistic Okapi BM25 model and the two representative word embedding methods for automatic query expansion was used. Various experiments were carried on TREC test collections. Stemming was performed and has shown a significant impact on the performance of Arabic text retrieval. Their finding indicates that deep average network could not improve performance using only BM25. However, the retrieval performance outperformed all baselines after integrating the two query expansion techniques.

While there are several studies that focused on the development of IR systems for Semitic languages, most of them have followed the techniques employed for morphologically simple languages such as English. This has not produced the desired retrieval result as documents could not be represented appropriately. Only few studies have tried to consider the issue of document representation in a systematic way [START_REF] Musaid | Arabic Information Retrieval System-Based on Morphological Analysis (AIRSMA): A Comparative Study of Word, Stem, Root and Morpho-Semantic Methods[END_REF]. In our approach, we address this crucial issue of document representation in the development of Amharic IR.

Amharic IR System Design and Text Representation

The main objective of this work is to identify the optimal representations for documents and queries in Amharic IR. Our approach focuses on the selection of the term structures and stopwords, based on the morphological characteristics of the language. Taking these issues into consideration, we also proposed an Amharic retrieval system as shown in Figure 1, which is slightly different from the basic architecture of IR systems. In the architecture we propose, stopwords are removed after the application of morphological analysis on documents and queries. Both documents and queries pass through the same preprocessing and linguistic text processing modules.

Appl. Sci. 2022, 12, x FOR PEER REVIEW 7 of 29

shown in Figure 1, which is slightly different from the basic architecture of IR systems. In the architecture we propose, stopwords are removed after the application of morphological analysis on documents and queries. Both documents and queries pass through the same preprocessing and linguistic text processing modules.

Figure 1. Architecture of the proposed Amharic IR system.

Text Preprocessing

The preprocessing involves removal of tags and punctuation, language specific tokenization, and character normalization. Punctuation marks are removed as they do not bear content relevant to IR system. Character normalization is required due to the fact that some characters have similar pronunciation but different graphemes. The characters ሐ /hə/, ኀ /hə/, ኸ /hə/ and their modifications are normalized to their corresponding modifications of ሀ /hə/. The character ሠ /sə/ and its modifications are normalized to their corresponding modifications of ሰ /sə/. The character ፀ /ts'ə/ and its modifications are normalized to their corresponding modifications of ጸ /ts'ə/. The character ዐ /ʔə/ and its modifications are normalized to their corresponding modifications of አ /ʔə/. The fourth orders ሃ /ha/, ሓ /ha/, ኃ /ha/ and ኻ /ha/ are normalized to ሀ /hə/ whereas the fourth orders ኣ /ʔa/ and ዓ /ʔa/ are normalized to አ /ʔə/. Thus, ስለጸሀፊዋ /sɨləts'əhafiwa 'about the secretary'/ can also be written as ሥለጸሀፊዋ /śɨləts'əhafiwa/, ስለጸሐፊዋ /sɨləts'əhafiwa/, ሥለጸሐፊዋ /śɨləts'əhafiwa/, ሥለጸኀፊዋ /śɨləts'əḫafiwa/, ስለጸኀፊዋ /sɨləts'əḫafiwa/, ሥለጸሐፊዋ /śɨləts'əhafiwa/, etc. although some of them rarely appear in a text.

Morphological Analysis

Morphological analysis is required for stemming and lemmatization where both aim to conflate variants of words into a unique unit, a stem or a root. These text units are then used to represent documents and queries for document indexing and query/document matching. Stemming is usually applied since lemmatization is more computationally consuming for just slight effectiveness improvements in IR tasks [START_REF] Balakrishnan | Stemming and lemmatization: A comparison of retrieval performances[END_REF]. Stemming has also been applied in Amharic IR systems [START_REF] Alemayehu | The effectiveness of stemming for information retrieval in Amharic. Program Electron[END_REF][START_REF] Mindaye | Design and implementation of Amharic search engine[END_REF]. In our work, we make the hypothesis that stemming is insufficient for Amharic and that more sophisticated text analysis should be used because of the complexity of the language.

Morphological variants of Amharic, especially verbs can have more than one stem types. From a given Amharic root, more than 10 basic stems could be generated [START_REF] Yimam | Yamarigna Sewasiw (Amharic Grammar)[END_REF]. For example, the morphological variants ነገረ /nəgərə 'he told'/, ተናጋሪ /tənagari 'orator'/, and አናገረ /ʔənagərə 'he communicated'/ have the basic stems ነገር-/nəgərɨ-/, ናጋር-/nagarɨ-/ and ናገር

Text Preprocessing

The preprocessing involves removal of tags and punctuation, language specific tokenization, and character normalization. Punctuation marks are removed as they do not bear content relevant to IR system. Character normalization is required due to the fact that some characters have similar pronunciation but different graphemes. The characters /h /, /h /, /h / and their modifications are normalized to their corresponding modifications of /h /. The character /s / and its modifications are normalized to their corresponding modifications of /s /. The character /ts' / and its modifications are normalized to their corresponding modifications of /ts' /. The character / Appl. Sci. 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually / and its modifications are normalized to their corresponding modifications of / Appl. Sci. 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually /. The fourth orders /ha/, /ha/, /ha/ and /ha/ are normalized to /h / whereas the fourth orders / 3 of 29 vailability of full-fledged low-level Amharic NLP tools makes it ted corpus automatically. Moreover, there is lack of standard ng it a major impediment to the development of Amharic IR and of this research work is: (1) to promote publicly accessible Amg a standard test collection for IR, morphologically annotated topwords list; and (2) to design Amharic IR system by investisentation of documents and queries considering both root-based esentations. r is organized as follows. Section 2 describes Amharic language tion 3 discusses related work. In Section 4, we present the proarchitecture along with various options to represent Amharic Section 5 presents the evaluation framework of the proposed system including the presentation of the resources and corpora, experimental results. In Section 6, we present our conclusion research directions.

em ing language of the government of Ethiopia currently having an over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken orld after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in lingua franca and the most literary language serving as a mee education system of the country for a long period. Amharic nd has 34 base characters along with modifications on the re-. The alphabet is conveniently written in a tabular format of t column represents the basic form with vowel ኧ /ə/ and the t modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / /ʔo/. For example, the base character በ /bə/ has the following /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are ch as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), olon), etc. It also borrows some punctuation marks such as '?' bet. Although Ethiopic alphabet has numeral system, the Arabic most commonly used by Amharic. ex morphology where many words could be generated through onal processes from other word forms. Many surface forms of m a base form through complex affixation, reduplication, and ion. Amharic words can be marked for a number of functions. be marked for a combination of person, case, gender, number, . An Amharic word might take up to four prefixes and five sufhe word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-(አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular ct verb/, አቸው /ʔətʃəwɨ third person plural object marker for pertive/, and ና /na conjunction/). Thousands of words can be generot or its stems by changing the shape of characters in a stem or ween root radicals, reduplicating one of the characters of the stem ding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for all variants have a single root representation template. The majorage are generated from verbal roots. Nouns, adjectives, and adverbal roots. The derivation of words from verbal roots usually a/ and / 3 of 29 pe. The unavailability of full-fledged low-level Amharic NLP tools makes it reate annotated corpus automatically. Moreover, there is lack of standard lection making it a major impediment to the development of Amharic IR and he objective of this research work is: (1) to promote publicly accessible Ames including a standard test collection for IR, morphologically annotated compiled stopwords list; and (2) to design Amharic IR system by investitimal representation of documents and queries considering both root-based ed text representations. of this paper is organized as follows. Section 2 describes Amharic language hology. Section 3 discusses related work. In Section 4, we present the proric IR system architecture along with various options to represent Amharic nd queries. Section 5 presents the evaluation framework of the proposed oc retrieval system including the presentation of the resources and corpora, l setup, and experimental results. In Section 6, we present our conclusion ard further research directions. anguage Writing System c is the working language of the government of Ethiopia currently having an pulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken age in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in haric is the lingua franca and the most literary language serving as a meruction in the education system of the country for a long period. Amharic c alphabet and has 34 base characters along with modifications on the ree characters. The alphabet is conveniently written in a tabular format of ns. The first column represents the basic form with vowel ኧ /ə/ and the ers represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following s: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are aracters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), ' (preface colon), etc. It also borrows some punctuation marks such as '?' atin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic em is rather most commonly used by Amharic.

Morphology

c has complex morphology where many words could be generated through nd derivational processes from other word forms. Many surface forms of e formed from a base form through complex affixation, reduplication, and interdigitation. Amharic words can be marked for a number of functions. , a verb can be marked for a combination of person, case, gender, number, , and mood. An Amharic word might take up to four prefixes and five sufr example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed efixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprofective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular er for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-Amharic root or its stems by changing the shape of characters in a stem or g vowels between root radicals, reduplicating one of the characters of the stem f, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for . However, all variants have a single root representation template. The majorin the language are generated from verbal roots. Nouns, adjectives, and adderived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually /. Thus, /s reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually l ts' hafiwa 'about the secretary'/ can also be written as /ś difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

2.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually l ts' hafiwa/, /s difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually l ts' hafiwa/, /ś availability of full-fledged low-level Amharic NLP tools makes it tated corpus automatically. Moreover, there is lack of standard ing it a major impediment to the development of Amharic IR and e of this research work is: (1) to promote publicly accessible Amng a standard test collection for IR, morphologically annotated stopwords list; and (2) to design Amharic IR system by investiesentation of documents and queries considering both root-based resentations. er is organized as follows. Section 2 describes Amharic language ction 3 discusses related work. In Section 4, we present the proem architecture along with various options to represent Amharic s. Section 5 presents the evaluation framework of the proposed l system including the presentation of the resources and corpora, d experimental results. In Section 6, we present our conclusion r research directions. tem rking language of the government of Ethiopia currently having an f over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in e lingua franca and the most literary language serving as a methe education system of the country for a long period. Amharic and has 34 base characters along with modifications on the res. The alphabet is conveniently written in a tabular format of t column represents the basic form with vowel ኧ /ə/ and the other difications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ple, the base character በ /bə/ has the following modifications: ቡ e/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters a/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface ws some punctuation marks such as '?' and '!' from Latin alphaalphabet has numeral system, the Arabic numeral system is rather y Amharic.

lex morphology where many words could be generated through tional processes from other word forms. Many surface forms of rom a base form through complex affixation, reduplication, and ation. Amharic words can be marked for a number of functions. n be marked for a combination of person, case, gender, number, . An Amharic word might take up to four prefixes and five sufple, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ -cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural ective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands ated from an Amharic root or its stems by changing the shape of root, inserting vowels between root radicals, reduplicating one of m or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are es for verbal words. However, all variants have a single root . The major-ity of words in the language are generated from verbal , and ad-verbs can be derived from verbal roots. The derivation of usually l ts' hafiwa/, /ś limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually l ts' hafiwa/, /s limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

2.2.

Amharic Morphology Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually l ts' hafiwa/, /ś limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes difficult to create annotated corpus automatically. Moreover, there is lack of standar reference collection making it a major impediment to the development of Amharic IR an NLP tools. The objective of this research work is: (1) to promote publicly accessible Am haric resources including a standard test collection for IR, morphologically annotate corpora and compiled stopwords list; and (2) to design Amharic IR system by invest gating the optimal representation of documents and queries considering both root-base and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic languag and its morphology. Section 3 discusses related work. In Section 4, we present the pro posed Amharic IR system architecture along with various options to represent Amhari documents and queries. Section 5 presents the evaluation framework of the propose Amharic adhoc retrieval system including the presentation of the resources and corpora experimental setup, and experimental results. In Section 6, we present our conclusio and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having a estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoke Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken i Ethiopia, Amharic is the lingua franca and the most literary language serving as a me dium of instruction in the education system of the country for a long period. Amhari uses Ethiopic alphabet and has 34 base characters along with modifications on the re spective base characters. The alphabet is conveniently written in a tabular format o seven columns. The first column represents the basic form with vowel ኧ /ə/ and the othe six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized character such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its ow punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (prefac colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rathe most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated throug inflectional and derivational processes from other word forms. Many surface forms o words can be formed from a base form through complex affixation, reduplication, an Semitic stem interdigitation. Amharic words can be marked for a number of function For example, a verb can be marked for a combination of person, case, gender, numbe tense, aspect, and mood. An Amharic word might take up to four prefixes and five su fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔə causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plura object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousand of words can be gener-ated from an Amharic root or its stems by changing the shape o characters in a stem or root, inserting vowels between root radicals, reduplicating one o the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There ar multiple stem templates for verbal words. However, all variants have a single roo representation template. The major-ity of words in the language are generated from verba roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation o words from verbal roots usually l ts' hafiwa/, etc. although some of them rarely appear in a text.

Morphological Analysis

Morphological analysis is required for stemming and lemmatization where both aim to conflate variants of words into a unique unit, a stem or a root. These text units are then used to represent documents and queries for document indexing and query/document matching. Stemming is usually applied since lemmatization is more computationally consuming for just slight effectiveness improvements in IR tasks [START_REF] Balakrishnan | Stemming and lemmatization: A comparison of retrieval performances[END_REF]. Stemming has also been applied in Amharic IR systems [START_REF] Alemayehu | The effectiveness of stemming for information retrieval in Amharic. Program Electron[END_REF][START_REF] Mindaye | Design and implementation of Amharic search engine[END_REF]. In our work, we make the hypothesis that stemming is insufficient for Amharic and that more sophisticated text analysis should be used because of the complexity of the language.

Morphological variants of Amharic, especially verbs can have more than one stem types. From a given Amharic root, more than 10 basic stems could be generated [START_REF] Yimam | Yamarigna Sewasiw (Amharic Grammar)[END_REF]. For example, the morphological variants /n g r 'he told'/, /t nagari 'orator'/, and / 3 of 29 ability of full-fledged low-level Amharic NLP tools makes it corpus automatically. Moreover, there is lack of standard t a major impediment to the development of Amharic IR and his research work is: (1) to promote publicly accessible Amstandard test collection for IR, morphologically annotated ords list; and (2) to design Amharic IR system by investiation of documents and queries considering both root-based tations. organized as follows. Section 2 describes Amharic language 3 discusses related work. In Section 4, we present the prochitecture along with various options to represent Amharic tion 5 presents the evaluation framework of the proposed m including the presentation of the resources and corpora, erimental results. In Section 6, we present our conclusion arch directions. language of the government of Ethiopia currently having an r 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken d after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in ua franca and the most literary language serving as a meducation system of the country for a long period. Amharic has 34 base characters along with modifications on the ree alphabet is conveniently written in a tabular format of lumn represents the basic form with vowel ኧ /ə/ and the odifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / For example, the base character በ /bə/ has the following , ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are s ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The nctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), ), etc. It also borrows some punctuation marks such as '?'

Although Ethiopic alphabet has numeral system, the Arabic st commonly used by Amharic. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of -/, -/nagar The rest of this paper is organized as follows. Section 2 describes Amharic la and its morphology. Section 3 discusses related work. In Section 4, we present posed Amharic IR system architecture along with various options to represent A documents and queries. Section 5 presents the evaluation framework of the p Amharic adhoc retrieval system including the presentation of the resources and c experimental setup, and experimental results. In Section 6, we present our con and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently ha estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are sp Ethiopia, Amharic is the lingua franca and the most literary language serving a dium of instruction in the education system of the country for a long period. A uses Ethiopic alphabet and has 34 base characters along with modifications on spective base characters. The alphabet is conveniently written in a tabular fo seven columns. The first column represents the basic form with vowel ኧ /ə/ and t six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifica /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized ch such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated inflectional and derivational processes from other word forms. Many surface f words can be formed from a base form through complex affixation, reduplicati Semitic stem interdigitation. Amharic words can be marked for a number of fu For example, a verb can be marked for a combination of person, case, gender, n tense, aspect, and mood. An Amharic word might take up to four prefixes and f fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨn constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffi ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third perso object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Th of words can be gener-ated from an Amharic root or its stems by changing the s characters in a stem or root, inserting vowels between root radicals, reduplicating the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. T multiple stem templates for verbal words. However, all variants have a sin representation template. The major-ity of words in the language are generated from roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The deriv -/ and /nag r 3 of 29 e. The unavailability of full-fledged low-level Amharic NLP tools makes it ate annotated corpus automatically. Moreover, there is lack of standard tion making it a major impediment to the development of Amharic IR and objective of this research work is: (1) to promote publicly accessible Amincluding a standard test collection for IR, morphologically annotated mpiled stopwords list; and (2) to design Amharic IR system by investimal representation of documents and queries considering both root-based text representations. f this paper is organized as follows. Section 2 describes Amharic language logy. Section 3 discusses related work. In Section 4, we present the pro-IR system architecture along with various options to represent Amharic queries. Section 5 presents the evaluation framework of the proposed retrieval system including the presentation of the resources and corpora, etup, and experimental results. In Section 6, we present our conclusion d further research directions.

guage riting System

s the working language of the government of Ethiopia currently having an ulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken ge in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in aric is the lingua franca and the most literary language serving as a mection in the education system of the country for a long period. Amharic lphabet and has 34 base characters along with modifications on the recharacters. The alphabet is conveniently written in a tabular format of . The first column represents the basic form with vowel ኧ /ə/ and the other esent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ For example, the base character በ /bə/ has the following modifications: ቡ ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own uch as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface lso borrows some punctuation marks such as '?' and '!' from Latin alphathiopic alphabet has numeral system, the Arabic numeral system is rather y used by Amharic. orphology as complex morphology where many words could be generated through derivational processes from other word forms. Many surface forms of ormed from a base form through complex affixation, reduplication, and terdigitation. Amharic words can be marked for a number of functions. verb can be marked for a combination of person, case, gender, number, nd mood. An Amharic word might take up to four prefixes and five sufr example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is m four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands e gener-ated from an Amharic root or its stems by changing the shape of stem or root, inserting vowels between root radicals, reduplicating one of of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root template. The major-ity of words in the language are generated from verbal -/, respectively. As a result, stemming provides different stems though the word variants are semantically similar, which means that Amharic verbal stems need one more reduction analysis for extracting words' roots. Indeed, verbal stems are formed from roots and all variants of an Amharic verb have one common root. For example, the common root for the aforementioned examples of morphological variants is --/n-g-r/. Therefore, roots are more appropriate than stems for Amharic as roots conflate word variants more accurately. Thus, we developed a new root-based representation for text representation for Amharic IR. We test our hypothesis experimentally by considering stem-based and root-based morphological analyses where extracted basic stems and roots of words from documents and queries. Basic stems serve for the formation of derived stems and surface forms of words. In Amharic, basic stems are usually derived from roots by inserting vowels between radicals.

Stem-Based Morphological Analysis

We created the stem-based index using the basic stems of words. Several words can be formed by attaching affixes to stems. Therefore, we performed morphological analysis for extracting stems from the rest of morphemes. We conflated variants of words to their basic stems. For example, the morphological analysis used to extract the stems of the words / ng a standard test collection for IR, morphologically annotated stopwords list; and (2) to design Amharic IR system by investiesentation of documents and queries considering both root-based resentations. er is organized as follows. Section 2 describes Amharic language ction 3 discusses related work. In Section 4, we present the prom architecture along with various options to represent Amharic s. Section 5 presents the evaluation framework of the proposed system including the presentation of the resources and corpora, d experimental results. In Section 6, we present our conclusion r research directions.

tem king language of the government of Ethiopia currently having an f over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in e lingua franca and the most literary language serving as a methe education system of the country for a long period. Amharic and has 34 base characters along with modifications on the res. The alphabet is conveniently written in a tabular format of st column represents the basic form with vowel ኧ /ə/ and the nt modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / /ʔo/. For example, the base character በ /bə/ has the following /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are ch as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The n punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), colon), etc. It also borrows some punctuation marks such as '?' -bet. Although Ethiopic alphabet has numeral system, the Arabic r most commonly used by Amharic. lex morphology where many words could be generated through tional processes from other word forms. Many surface forms of rom a base form through complex affixation, reduplication, and tion. Amharic words can be marked for a number of functions. n be marked for a combination of person, case, gender, number, . An Amharic word might take up to four prefixes and five sufthe word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprob (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular ect verb/, አቸው /ʔətʃəwɨ third person plural object marker for persative/, and ና /na conjunction/). Thousands of words can be generoot or its stems by changing the shape of characters in a stem or tween root radicals, reduplicating one of the characters of the stem dding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for , all variants have a single root representation template. The majoruage are generated from verbal roots. Nouns, adjectives, and adm verbal roots. The derivation of words from verbal roots usually l mharic is the lingua franca and the most literary language serving as a mestruction in the education system of the country for a long period. Amharic pic alphabet and has 34 base characters along with modifications on the rese characters. The alphabet is conveniently written in a tabular format of mns. The first column represents the basic form with vowel ኧ /ə/ and the other epresent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ns such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface It also borrows some punctuation marks such as '?' and '!' from Latin alphagh Ethiopic alphabet has numeral system, the Arabic numeral system is rather only used by Amharic.

c Morphology ric has complex morphology where many words could be generated through l and derivational processes from other word forms. Many surface forms of be formed from a base form through complex affixation, reduplication, and m interdigitation. Amharic words can be marked for a number of functions. le, a verb can be marked for a combination of person, case, gender, number, ct, and mood. An Amharic word might take up to four prefixes and five suf-For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / son singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural ker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands an be gener-ated from an Amharic root or its stems by changing the shape of in a stem or root, inserting vowels between root radicals, reduplicating one of ers of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are em templates for verbal words. However, all variants have a single root ion template. The major-ity of words in the language are generated from verbal ns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of verbal roots usually

t m l sum
Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually 'they have not returned'/ and /k bet s bot and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually u 'from his families'/ are shown as follows (see Notations at the end of this article).

_ _ _ _ _ _ _
y of full-fledged low-level Amharic NLP tools makes it us automatically. Moreover, there is lack of standard ajor impediment to the development of Amharic IR and search work is: (1) to promote publicly accessible Amard test collection for IR, morphologically annotated list; and (2) to design Amharic IR system by investiof documents and queries considering both root-based ns. nized as follows. Section 2 describes Amharic language cusses related work. In Section 4, we present the procture along with various options to represent Amharic 5 presents the evaluation framework of the proposed cluding the presentation of the resources and corpora, ental results. In Section 6, we present our conclusion directions.

age of the government of Ethiopia currently having an million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken r Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in ranca and the most literary language serving as a meion system of the country for a long period. Amharic 4 base characters along with modifications on the rehabet is conveniently written in a tabular format of represents the basic form with vowel ኧ /ə/ and the cations with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / example, the base character በ /bə/ has the following ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The tions such as '።' (full stop), '፣' (comma), '፤' (semicolon), . It also borrows some punctuation marks such as '?' ugh Ethiopic alphabet has numeral system, the Arabic monly used by Amharic. ology where many words could be generated through esses from other word forms. Many surface forms of e form through complex affixation, reduplication, and aric words can be marked for a number of functions. ed for a combination of person, case, gender, number, aric word might take up to four prefixes and five suf-ላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed on/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciproərɨ 'tie'/); and four suffixes (ኩ /ku first person singular ቸው /ʔətʃəwɨ third person plural object marker for per-ና /na conjunction/). Thousands of words can be generstems by changing the shape of characters in a stem or t radicals, reduplicating one of the characters of the stem es on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for ts have a single root representation template. The majorenerated from verbal roots. Nouns, adjectives, and adoots. The derivation of words from verbal roots usually l ystem orking language of the government of Ethiopia currently having an of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken he world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in the lingua franca and the most literary language serving as a men the education system of the country for a long period. Amharic et and has 34 base characters along with modifications on the reters. The alphabet is conveniently written in a tabular format of irst column represents the basic form with vowel ኧ /ə/ and the other odifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ample, the base character በ /bə/ has the following modifications: ቡ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters wa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface rows some punctuation marks such as '?' and '!' from Latin alphac alphabet has numeral system, the Arabic numeral system is rather by Amharic. gy plex morphology where many words could be generated through ational processes from other word forms. Many surface forms of from a base form through complex affixation, reduplication, and itation. Amharic words can be marked for a number of functions. can be marked for a combination of person, case, gender, number, od. An Amharic word might take up to four prefixes and five sufmple, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is r prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ar subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural -fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands r-ated from an Amharic root or its stems by changing the shape of r root, inserting vowels between root radicals, reduplicating one of stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are ates for verbal words. However, all variants have a single root te. The major-ity of words in the language are generated from verbal es, and ad-verbs can be derived from verbal roots. The derivation of ts usually _t _m l s Writing System ic is the working language of the government of Ethiopia currently having an opulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken uage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in mharic is the lingua franca and the most literary language serving as a metruction in the education system of the country for a long period. Amharic ic alphabet and has 34 base characters along with modifications on the rese characters. The alphabet is conveniently written in a tabular format of ns. The first column represents the basic form with vowel ኧ /ə/ and the other present modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ o/. For example, the base character በ /bə/ has the following modifications: ቡ ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters wa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own s such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface t also borrows some punctuation marks such as '?' and '!' from Latin alphah Ethiopic alphabet has numeral system, the Arabic numeral system is rather only used by Amharic. Morphology ic has complex morphology where many words could be generated through and derivational processes from other word forms. Many surface forms of e formed from a base form through complex affixation, reduplication, and interdigitation. Amharic words can be marked for a number of functions. , a verb can be marked for a combination of person, case, gender, number, t, and mood. An Amharic word might take up to four prefixes and five suf-For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / on singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural er for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands n be gener-ated from an Amharic root or its stems by changing the shape of a stem or root, inserting vowels between root radicals, reduplicating one of rs of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are m templates for verbal words. However, all variants have a single root on template. The major-ity of words in the language are generated from verbal s, adjectives, and ad-verbs can be derived from verbal roots. The derivation of verbal roots usually _ e unavailability of full-fledged low-level Amharic NLP tools makes it nnotated corpus automatically. Moreover, there is lack of standard making it a major impediment to the development of Amharic IR and ctive of this research work is: (1) to promote publicly accessible Amuding a standard test collection for IR, morphologically annotated ed stopwords list; and (2) to design Amharic IR system by investiepresentation of documents and queries considering both root-based representations. paper is organized as follows. Section 2 describes Amharic language . Section 3 discusses related work. In Section 4, we present the proystem architecture along with various options to represent Amharic ries. Section 5 presents the evaluation framework of the proposed val system including the presentation of the resources and corpora, and experimental results. In Section 6, we present our conclusion ther research directions.

e System working language of the government of Ethiopia currently having an n of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in s the lingua franca and the most literary language serving as a mein the education system of the country for a long period. Amharic bet and has 34 base characters along with modifications on the recters. The alphabet is conveniently written in a tabular format of first column represents the basic form with vowel ኧ /ə/ and the resent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / d ኦ /ʔo/. For example, the base character በ /bə/ has the following /, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are s such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), ace colon), etc. It also borrows some punctuation marks such as '?' pha-bet. Although Ethiopic alphabet has numeral system, the Arabic ather most commonly used by Amharic. logy mplex morphology where many words could be generated through ivational processes from other word forms. Many surface forms of d from a base form through complex affixation, reduplication, and igitation. Amharic words can be marked for a number of functions.

can be marked for a combination of person, case, gender, number, ood. An Amharic word might take up to four prefixes and five sufle, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciproverb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular erfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perccusative/, and ና /na conjunction/). Thousands of words can be generric root or its stems by changing the shape of characters in a stem or ls between root radicals, reduplicating one of the characters of the stem y adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for ver, all variants have a single root representation template. The majoranguage are generated from verbal roots. Nouns, adjectives, and adfrom verbal roots. The derivation of words from verbal roots usually u_m mharic Writing System mharic is the working language of the government of Ethiopia currently having an ated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken tic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in pia, Amharic is the lingua franca and the most literary language serving as a meof instruction in the education system of the country for a long period. Amharic Ethiopic alphabet and has 34 base characters along with modifications on the reive base characters. The alphabet is conveniently written in a tabular format of columns. The first column represents the basic form with vowel ኧ /ə/ and the other ders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ nd ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own tuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface ), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphalthough Ethiopic alphabet has numeral system, the Arabic numeral system is rather commonly used by Amharic. mharic Morphology mharic has complex morphology where many words could be generated through tional and derivational processes from other word forms. Many surface forms of s can be formed from a base form through complex affixation, reduplication, and tic stem interdigitation. Amharic words can be marked for a number of functions. xample, a verb can be marked for a combination of person, case, gender, number, , aspect, and mood. An Amharic word might take up to four prefixes and five suf- [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ tive/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / st person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural t marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands rds can be gener-ated from an Amharic root or its stems by changing the shape of cters in a stem or root, inserting vowels between root radicals, reduplicating one of haracters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are ple stem templates for verbal words. However, all variants have a single root sentation template. The major-ity of words in the language are generated from verbal . Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of s from verbal roots usually k _bet s b

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually _ limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually ot The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually _ limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually

u [neg]-[pas]-[stem]-[3,p]-[ncmp] [pre]-[stem]-[p]-[3,s,m]
Furthermore, basic stems are used to form derived stems, which in turn are used for the formation of surface forms of words. The derived stems include causative ( -/ Appl. Sci. 2022, 12, x FOR PEER REVIEW 3 of limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes difficult to create annotated corpus automatically. Moreover, there is lack of standar reference collection making it a major impediment to the development of Amharic IR an NLP tools. The objective of this research work is: (1) to promote publicly accessible Am haric resources including a standard test collection for IR, morphologically annotate corpora and compiled stopwords list; and (2) to design Amharic IR system by invest gating the optimal representation of documents and queries considering both root-base and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic languag and its morphology. Section 3 discusses related work. In Section 4, we present the pro posed Amharic IR system architecture along with various options to represent Amhar documents and queries. Section 5 presents the evaluation framework of the propose Amharic adhoc retrieval system including the presentation of the resources and corpor experimental setup, and experimental results. In Section 6, we present our conclusio and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having a estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoke Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken i Ethiopia, Amharic is the lingua franca and the most literary language serving as a m dium of instruction in the education system of the country for a long period. Amhar uses Ethiopic alphabet and has 34 base characters along with modifications on the r spective base characters. The alphabet is conveniently written in a tabular format o seven columns.

The first column represents the basic form with vowel ኧ /ə/ and th other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the followin modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there ar labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. Th language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as ' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arab numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated throug inflectional and derivational processes from other word forms. Many surface forms o words can be formed from a base form through complex affixation, reduplication, an Semitic stem interdigitation. Amharic words can be marked for a number of function For example, a verb can be marked for a combination of person, case, gender, numbe tense, aspect, and mood. An Amharic word might take up to four prefixes and five su fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructe from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singula subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for pe fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gene ated from an Amharic root or its stems by changing the shape of characters in a stem o root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates fo verbal words. However, all variants have a single root representation template. The majo ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad verbs can be derived from verbal roots. The derivation of words from verbal roots usual -/ and -/ 3 of 29 ailability of full-fledged low-level Amharic NLP tools makes it ted corpus automatically. Moreover, there is lack of standard g it a major impediment to the development of Amharic IR and of this research work is: (1) to promote publicly accessible Ama standard test collection for IR, morphologically annotated pwords list; and (2) to design Amharic IR system by investientation of documents and queries considering both root-based sentations. r is organized as follows. Section 2 describes Amharic language ion 3 discusses related work. In Section 4, we present the proarchitecture along with various options to represent Amharic Section 5 presents the evaluation framework of the proposed ystem including the presentation of the resources and corpora, experimental results. In Section 6, we present our conclusion esearch directions. m ng language of the government of Ethiopia currently having an over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken orld after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in lingua franca and the most literary language serving as a mee education system of the country for a long period. Amharic d has 34 base characters along with modifications on the re-The alphabet is conveniently written in a tabular format of column represents the basic form with vowel ኧ /ə/ and the t modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔo/. For example, the base character በ /bə/ has the following /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are h as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), lon), etc. It also borrows some punctuation marks such as '?' et. Although Ethiopic alphabet has numeral system, the Arabic most commonly used by Amharic.

x morphology where many words could be generated through nal processes from other word forms. Many surface forms of m a base form through complex affixation, reduplication, and on. Amharic words can be marked for a number of functions. be marked for a combination of person, case, gender, number, An Amharic word might take up to four prefixes and five sufe word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed reposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-(አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular t verb/, አቸው /ʔətʃəwɨ third person plural object marker for perive/, and ና /na conjunction/). Thousands of words can be genert or its stems by changing the shape of characters in a stem or een root radicals, reduplicating one of the characters of the stem ing affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for ll variants have a single root representation template. The majorge are generated from verbal roots. Nouns, adjectives, and adverbal roots. The derivation of words from verbal roots usually s oc retrieval system including the presentation of the resources and corpora, l setup, and experimental results. In Section 6, we present our conclusion ard further research directions. anguage Writing System c is the working language of the government of Ethiopia currently having an pulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken age in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in haric is the lingua franca and the most literary language serving as a meruction in the education system of the country for a long period. Amharic c alphabet and has 34 base characters along with modifications on the ree characters. The alphabet is conveniently written in a tabular format of ns. The first column represents the basic form with vowel ኧ /ə/ and the other resent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /. For example, the base character በ /bə/ has the following modifications: ቡ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters wa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface also borrows some punctuation marks such as '?' and '!' from Latin alphah Ethiopic alphabet has numeral system, the Arabic numeral system is rather nly used by Amharic. Morphology c has complex morphology where many words could be generated through nd derivational processes from other word forms. Many surface forms of e formed from a base form through complex affixation, reduplication, and interdigitation. Amharic words can be marked for a number of functions. , a verb can be marked for a combination of person, case, gender, number, , and mood. An Amharic word might take up to four prefixes and five suf-For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / n singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural r for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands be gener-ated from an Amharic root or its stems by changing the shape of a stem or root, inserting vowels between root radicals, reduplicating one of s of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root n template. The major-ity of words in the language are generated from verbal , adjectives, and ad-verbs can be derived from verbal roots. The derivation of erbal roots usually -/), passive ( -/t -/), infinitive ( -/m -/), and reduplicative types of verbal stems. For example, the variants /t d w l 'is called'/, /k m d w lwa 'as soon as she called'/, /b

3 of 29 in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it to create annotated corpus automatically. Moreover, there is lack of standard e collection making it a major impediment to the development of Amharic IR and ols. The objective of this research work is: (1) to promote publicly accessible Amsources including a standard test collection for IR, morphologically annotated and compiled stopwords list; and (2) to design Amharic IR system by investihe optimal representation of documents and queries considering both root-based -based text representations. e rest of this paper is organized as follows. Section 2 describes Amharic language morphology. Section 3 discusses related work. In Section 4, we present the promharic IR system architecture along with various options to represent Amharic nts and queries. Section 5 presents the evaluation framework of the proposed c adhoc retrieval system including the presentation of the resources and corpora, ental setup, and experimental results. In Section 6, we present our conclusion forward further research directions.

aric Language haric Writing System haric is the working language of the government of Ethiopia currently having an ed population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in a, Amharic is the lingua franca and the most literary language serving as a mef instruction in the education system of the country for a long period. Amharic hiopic alphabet and has 34 base characters along with modifications on the rebase characters. The alphabet is conveniently written in a tabular format of olumns.

The first column represents the basic form with vowel ኧ /ə/ and the x orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following ations: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are ed characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The e has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), n), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' rom Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic l system is rather most commonly used by Amharic.

haric Morphology haric has complex morphology where many words could be generated through nal and derivational processes from other word forms. Many surface forms of an be formed from a base form through complex affixation, reduplication, and stem interdigitation. Amharic words can be marked for a number of functions. mple, a verb can be marked for a combination of person, case, gender, number, spect, and mood. An Amharic word might take up to four prefixes and five suf-]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed ur prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciproe perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for pererb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generm an Amharic root or its stems by changing the shape of characters in a stem or erting vowels between root radicals, reduplicating one of the characters of the stem itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for ords. However, all variants have a single root representation template. The majorords in the language are generated from verbal roots. Nouns, adjectives, and adn be derived from verbal roots. The derivation of words from verbal roots usually s posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language 2.1. Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually d w l 'since he caused to call'/, and /sid waw posed Amharic IR system architecture along with various options to represent documents and queries. Section 5 presents the evaluation framework of the Amharic adhoc retrieval system including the presentation of the resources and experimental setup, and experimental results. In Section 6, we present our co and put forward further research directions.

Amharic Language 2.1. Amharic Writing System

Amharic is the working language of the government of Ethiopia currently h estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonl Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are s Ethiopia, Amharic is the lingua franca and the most literary language serving dium of instruction in the education system of the country for a long period. uses Ethiopic alphabet and has 34 base characters along with modifications o spective base characters. The alphabet is conveniently written in a tabular f seven columns. The first column represents the basic form with vowel ኧ /ə/ and six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modific /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized c such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has als punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦ colon), etc. It also borrows some punctuation marks such as '?' and '!' from Lat bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated inflectional and derivational processes from other word forms. Many surface words can be formed from a base form through complex affixation, reduplica Semitic stem interdigitation. Amharic words can be marked for a number of f For example, a verb can be marked for a combination of person, case, gender, tense, aspect, and mood. An Amharic word might take up to four prefixes and fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəw constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suf ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third pers object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). T of words can be gener-ated from an Amharic root or its stems by changing the characters in a stem or root, inserting vowels between root radicals, reduplicati the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. multiple stem templates for verbal words. However, all variants have a si representation template. The major-ity of words in the language are generated fro roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The der words from verbal roots usually lu 'as they called each other'/ have the derived stems -/t d w and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language 2.1. Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually l and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language 2.1. Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually -/, -/m d w l and its morphology. Section 3 discusses related work. In Section 4, we pres posed Amharic IR system architecture along with various options to represe documents and queries. Section 5 presents the evaluation framework of th Amharic adhoc retrieval system including the presentation of the resources a experimental setup, and experimental results. In Section 6, we present our and put forward further research directions.

Amharic Language 2.1. Amharic Writing System

Amharic is the working language of the government of Ethiopia currentl estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commo Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages a Ethiopia, Amharic is the lingua franca and the most literary language servi dium of instruction in the education system of the country for a long perio uses Ethiopic alphabet and has 34 base characters along with modification spective base characters. The alphabet is conveniently written in a tabula seven columns. The first column represents the basic form with vowel ኧ /ə/ a six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following mod /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialize such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), colon), etc. It also borrows some punctuation marks such as '?' and '!' from bet. Although Ethiopic alphabet has numeral system, the Arabic numeral syst most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be genera inflectional and derivational processes from other word forms. Many surfa words can be formed from a base form through complex affixation, redupl Semitic stem interdigitation. Amharic words can be marked for a number o For example, a verb can be marked for a combination of person, case, gend tense, aspect, and mood. An Amharic word might take up to four prefixes a fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negatio causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four s ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third p object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/) of words can be gener-ated from an Amharic root or its stems by changing characters in a stem or root, inserting vowels between root radicals, reduplic the characters of the stem or word itself, and by adding affixes on stems [22 multiple stem templates for verbal words. However, all variants have a representation template. The major-ity of words in the language are generated roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The d words from verbal roots usually -/, -/ 3 of 29 ailability of full-fledged low-level Amharic NLP tools makes it ed corpus automatically. Moreover, there is lack of standard g it a major impediment to the development of Amharic IR and f this research work is: (1) to promote publicly accessible Ama standard test collection for IR, morphologically annotated pwords list; and (2) to design Amharic IR system by investintation of documents and queries considering both root-based sentations.

is organized as follows. Section 2 describes Amharic language on 3 discusses related work. In Section 4, we present the proarchitecture along with various options to represent Amharic ection 5 presents the evaluation framework of the proposed stem including the presentation of the resources and corpora, experimental results. In Section 6, we present our conclusion esearch directions.

ng language of the government of Ethiopia currently having an ver 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken orld after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in lingua franca and the most literary language serving as a meeducation system of the country for a long period. Amharic d has 34 base characters along with modifications on the re-The alphabet is conveniently written in a tabular format of column represents the basic form with vowel ኧ /ə/ and the modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / o/. For example, the base character በ /bə/ has the following /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), lon), etc. It also borrows some punctuation marks such as '?' et. Although Ethiopic alphabet has numeral system, the Arabic ost commonly used by Amharic.

x morphology where many words could be generated through nal processes from other word forms. Many surface forms of a base form through complex affixation, reduplication, and n. Amharic words can be marked for a number of functions. e marked for a combination of person, case, gender, number, n Amharic word might take up to four prefixes and five sufe word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed reposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular verb/, አቸው /ʔətʃəwɨ third person plural object marker for perive/, and ና /na conjunction/). Thousands of words can be genert or its stems by changing the shape of characters in a stem or een root radicals, reduplicating one of the characters of the stem ing affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for l variants have a single root representation template. The majorge are generated from verbal roots. Nouns, adjectives, and adverbal roots. The derivation of words from verbal roots usually s of this paper is organized as follows. Section 2 describes Amharic language hology. Section 3 discusses related work. In Section 4, we present the proric IR system architecture along with various options to represent Amharic nd queries. Section 5 presents the evaluation framework of the proposed c retrieval system including the presentation of the resources and corpora, setup, and experimental results. In Section 6, we present our conclusion ard further research directions.

anguage riting System

is the working language of the government of Ethiopia currently having an pulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken age in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in haric is the lingua franca and the most literary language serving as a meuction in the education system of the country for a long period. Amharic alphabet and has 34 base characters along with modifications on the recharacters. The alphabet is conveniently written in a tabular format of s. The first column represents the basic form with vowel ኧ /ə/ and the other resent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ . For example, the base character በ /bə/ has the following modifications: ቡ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters a/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface also borrows some punctuation marks such as '?' and '!' from Latin alpha-Ethiopic alphabet has numeral system, the Arabic numeral system is rather nly used by Amharic. orphology has complex morphology where many words could be generated through nd derivational processes from other word forms. Many surface forms of formed from a base form through complex affixation, reduplication, and interdigitation. Amharic words can be marked for a number of functions. a verb can be marked for a combination of person, case, gender, number, and mood. An Amharic word might take up to four prefixes and five suf-For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / n singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural r for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands be gener-ated from an Amharic root or its stems by changing the shape of a stem or root, inserting vowels between root radicals, reduplicating one of s of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root n template. The major-ity of words in the language are generated from verbal adjectives, and ad-verbs can be derived from verbal roots. The derivation of erbal roots usually d w l e rest of this paper is organized as follows. Section 2 describes Amharic language morphology. Section 3 discusses related work. In Section 4, we present the pro-Amharic IR system architecture along with various options to represent Amharic ents and queries. Section 5 presents the evaluation framework of the proposed ic adhoc retrieval system including the presentation of the resources and corpora, ental setup, and experimental results. In Section 6, we present our conclusion t forward further research directions.

aric Language haric Writing System mharic is the working language of the government of Ethiopia currently having an ted population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in ia, Amharic is the lingua franca and the most literary language serving as a mef instruction in the education system of the country for a long period. Amharic thiopic alphabet and has 34 base characters along with modifications on the ree base characters. The alphabet is conveniently written in a tabular format of olumns. The first column represents the basic form with vowel ኧ /ə/ and the other ers represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters s ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphathough Ethiopic alphabet has numeral system, the Arabic numeral system is rather mmonly used by Amharic. haric Morphology mharic has complex morphology where many words could be generated through onal and derivational processes from other word forms. Many surface forms of can be formed from a base form through complex affixation, reduplication, and stem interdigitation. Amharic words can be marked for a number of functions. mple, a verb can be marked for a combination of person, case, gender, number, spect, and mood. An Amharic word might take up to four prefixes and five suf- [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is cted from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ve/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands ds can be gener-ated from an Amharic root or its stems by changing the shape of ers in a stem or root, inserting vowels between root radicals, reduplicating one of racters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are le stem templates for verbal words. However, all variants have a single root ntation template. The major-ity of words in the language are generated from verbal ouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of from verbal roots usually -/ and -/d waw l

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language 2.1. Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually -/, respectively and a basic stem -/d w l

The rest of this paper is organized as follows. Section 2 describes Amha and its morphology. Section 3 discusses related work. In Section 4, we pres posed Amharic IR system architecture along with various options to repres documents and queries. Section 5 presents the evaluation framework of th Amharic adhoc retrieval system including the presentation of the resources a experimental setup, and experimental results. In Section 6, we present ou and put forward further research directions.

Amharic Language 2.1. Amharic Writing System

Amharic is the working language of the government of Ethiopia current estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most comm Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages a Ethiopia, Amharic is the lingua franca and the most literary language servi dium of instruction in the education system of the country for a long perio uses Ethiopic alphabet and has 34 base characters along with modification spective base characters. The alphabet is conveniently written in a tabula seven columns. The first column represents the basic form with vowel ኧ /ə/ a six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following mod /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialize such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), colon), etc. It also borrows some punctuation marks such as '?' and '!' from bet. Although Ethiopic alphabet has numeral system, the Arabic numeral sys most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be genera inflectional and derivational processes from other word forms. Many surfa words can be formed from a base form through complex affixation, redup Semitic stem interdigitation. Amharic words can be marked for a number o For example, a verb can be marked for a combination of person, case, gend tense, aspect, and mood. An Amharic word might take up to four prefixes a fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negatio causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third p object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/) of words can be gener-ated from an Amharic root or its stems by changing characters in a stem or root, inserting vowels between root radicals, reduplic the characters of the stem or word itself, and by adding affixes on stems [22 multiple stem templates for verbal words. However, all variants have a representation template. The major-ity of words in the language are generated roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The d words from verbal roots usually -/. With regard to their meaning, there is no conceptual difference between derived and basic stems. Moreover, the origins of derived stems are basic stems, and basic stems are the shortest and the most common stems for many variants (see Table 3 where core meaning is 'kill'). For the stem-based indexing and retrieval, we represent the variants of words by their basic stems. Table 3. Derived and basic stems in Amharic.

Variant Derived Stem Basic Stem

/k t g daj in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it to create annotated corpus automatically. Moreover, there is lack of standard e collection making it a major impediment to the development of Amharic IR and ls. The objective of this research work is: (1) to promote publicly accessible Amsources including a standard test collection for IR, morphologically annotated and compiled stopwords list; and (2) to design Amharic IR system by investie optimal representation of documents and queries considering both root-based -based text representations. rest of this paper is organized as follows. Section 2 describes Amharic language orphology. Section 3 discusses related work. In Section 4, we present the promharic IR system architecture along with various options to represent Amharic nts and queries. Section 5 presents the evaluation framework of the proposed c adhoc retrieval system including the presentation of the resources and corpora, ental setup, and experimental results. In Section 6, we present our conclusion forward further research directions.

ric Language aric Writing System

haric is the working language of the government of Ethiopia currently having an d population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in , Amharic is the lingua franca and the most literary language serving as a meinstruction in the education system of the country for a long period. Amharic iopic alphabet and has 34 base characters along with modifications on the rebase characters. The alphabet is conveniently written in a tabular format of lumns. The first column represents the basic form with vowel ኧ /ə/ and the other rs represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own tions such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface tc. It also borrows some punctuation marks such as '?' and '!' from Latin alphaough Ethiopic alphabet has numeral system, the Arabic numeral system is rather mmonly used by Amharic. aric Morphology haric has complex morphology where many words could be generated through nal and derivational processes from other word forms. Many surface forms of an be formed from a base form through complex affixation, reduplication, and stem interdigitation. Amharic words can be marked for a number of functions.

ple, a verb can be marked for a combination of person, case, gender, number, pect, and mood. An Amharic word might take up to four prefixes and five suf-8]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ted from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ e/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / erson singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural arker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands s can be gener-ated from an Amharic root or its stems by changing the shape of rs in a stem or root, inserting vowels between root radicals, reduplicating one of acters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are stem templates for verbal words. However, all variants have a single root tation template. The major-ity of words in the language are generated from verbal ouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of om verbal roots usually / -/t g dal limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language 2.1. Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually -/ -/g dal limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language 2.1. Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually

-/ /s 3 of 29
. The unavailability of full-fledged low-level Amharic NLP tools makes it te annotated corpus automatically. Moreover, there is lack of standard tion making it a major impediment to the development of Amharic IR and objective of this research work is: (1) to promote publicly accessible Amincluding a standard test collection for IR, morphologically annotated mpiled stopwords list; and (2) to design Amharic IR system by investial representation of documents and queries considering both root-based text representations. this paper is organized as follows. Section 2 describes Amharic language logy. Section 3 discusses related work. In Section 4, we present the pro-IR system architecture along with various options to represent Amharic queries. Section 5 presents the evaluation framework of the proposed retrieval system including the presentation of the resources and corpora, tup, and experimental results. In Section 6, we present our conclusion further research directions.

guage iting System

the working language of the government of Ethiopia currently having an lation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken e in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in ric is the lingua franca and the most literary language serving as a metion in the education system of the country for a long period. Amharic lphabet and has 34 base characters along with modifications on the reharacters. The alphabet is conveniently written in a tabular format of The first column represents the basic form with vowel ኧ /ə/ and the other sent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ or example, the base character በ /bə/ has the following modifications: ቡ a/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters , ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ch as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface so borrows some punctuation marks such as '?' and '!' from Latin alphathiopic alphabet has numeral system, the Arabic numeral system is rather used by Amharic. rphology as complex morphology where many words could be generated through derivational processes from other word forms. Many surface forms of rmed from a base form through complex affixation, reduplication, and terdigitation. Amharic words can be marked for a number of functions. verb can be marked for a combination of person, case, gender, number, d mood. An Amharic word might take up to four prefixes and five sufr example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is m four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ingular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural or per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands gener-ated from an Amharic root or its stems by changing the shape of tem or root, inserting vowels between root radicals, reduplicating one of f the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root emplate. The major-ity of words in the language are generated from verbal jectives, and ad-verbs can be derived from verbal roots. The derivation of bal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language 2.1. Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language 2.1. Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually -/ /kas 3 of 29 e. The unavailability of full-fledged low-level Amharic NLP tools makes it ate annotated corpus automatically. Moreover, there is lack of standard ction making it a major impediment to the development of Amharic IR and e objective of this research work is: (1) to promote publicly accessible Ams including a standard test collection for IR, morphologically annotated ompiled stopwords list; and (2) to design Amharic IR system by investiimal representation of documents and queries considering both root-based d text representations. f this paper is organized as follows. Section 2 describes Amharic language ology. Section 3 discusses related work. In Section 4, we present the proic IR system architecture along with various options to represent Amharic d queries. Section 5 presents the evaluation framework of the proposed c retrieval system including the presentation of the resources and corpora, setup, and experimental results. In Section 6, we present our conclusion rd further research directions.

nguage riting System

is the working language of the government of Ethiopia currently having an ulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken age in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in aric is the lingua franca and the most literary language serving as a mection in the education system of the country for a long period. Amharic alphabet and has 34 base characters along with modifications on the recharacters. The alphabet is conveniently written in a tabular format of s. The first column represents the basic form with vowel ኧ /ə/ and the other resent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ For example, the base character በ /bə/ has the following modifications: ቡ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters a/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface also borrows some punctuation marks such as '?' and '!' from Latin alpha-Ethiopic alphabet has numeral system, the Arabic numeral system is rather ly used by Amharic. orphology has complex morphology where many words could be generated through d derivational processes from other word forms. Many surface forms of formed from a base form through complex affixation, reduplication, and interdigitation. Amharic words can be marked for a number of functions. a verb can be marked for a combination of person, case, gender, number, and mood. An Amharic word might take up to four prefixes and five sufor example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is om four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands be gener-ated from an Amharic root or its stems by changing the shape of stem or root, inserting vowels between root radicals, reduplicating one of of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root template. The major-ity of words in the language are generated from verbal adjectives, and ad-verbs can be derived from verbal roots. The derivation of rbal roots usually

g d l / -/ R REVIEW 3 of 29
limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language 2.1. Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language 2.1. Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language 2.1. Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language 2.1. Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually -/

Although basic stems are better to conflate more variants than derived stems, more than one type of basic stems exist for variants (see Table 3). Therefore, in case of verbs, it is impossible to conflate Amharic variants even using basic stems. However, variants of primary nouns, adjectives, and adverbs have one common basic stem. Therefore, verbs and words derived from verbs need further morphological analysis to be represented by a common form. The morphological analysis of some words requires palatalization to extract basic stems. This has been achieved after separating -and -from a stem. For example, the morphological analyses of the words /j godZiwot The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually Appl. Sci. 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language 2.1. Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually 'of harmful [p]'/, /g dajot 3 of 29 ited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it ficult to create annotated corpus automatically. Moreover, there is lack of standard erence collection making it a major impediment to the development of Amharic IR and P tools. The objective of this research work is: (1) to promote publicly accessible Amric resources including a standard test collection for IR, morphologically annotated pora and compiled stopwords list; and (2) to design Amharic IR system by investiting the optimal representation of documents and queries considering both root-based d stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language d its morphology. Section 3 discusses related work. In Section 4, we present the prosed Amharic IR system architecture along with various options to represent Amharic cuments and queries. Section 5 presents the evaluation framework of the proposed haric adhoc retrieval system including the presentation of the resources and corpora, erimental setup, and experimental results. In Section 6, we present our conclusion d put forward further research directions.

mharic Language

. Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an imated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken itic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in iopia, Amharic is the lingua franca and the most literary language serving as a mem of instruction in the education system of the country for a long period. Amharic es Ethiopic alphabet and has 34 base characters along with modifications on the reective base characters. The alphabet is conveniently written in a tabular format of en columns. The first column represents the basic form with vowel ኧ /ə/ and the other orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ , and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters ch as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own nctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface on), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphat. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather st commonly used by Amharic.

. Amharic Morphology

Amharic has complex morphology where many words could be generated through lectional and derivational processes from other word forms. Many surface forms of rds can be formed from a base form through complex affixation, reduplication, and itic stem interdigitation. Amharic words can be marked for a number of functions. r example, a verb can be marked for a combination of person, case, gender, number, se, aspect, and mood. An Amharic word might take up to four prefixes and five sufes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is structed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first rson singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object rker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of rds can be gener-ated from an Amharic root or its stems by changing the shape of racters in a stem or root, inserting vowels between root radicals, reduplicating one of characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are ltiple stem templates for verbal words. However, all variants have a single root resentation template. The major-ity of words in the language are generated from verbal ts. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of rds from verbal roots usually 3 of 29 scope. The unavailability of full-fledged low-level Amharic NLP tools makes it create annotated corpus automatically. Moreover, there is lack of standard ollection making it a major impediment to the development of Amharic IR and The objective of this research work is: (1) to promote publicly accessible Amrces including a standard test collection for IR, morphologically annotated d compiled stopwords list; and (2) to design Amharic IR system by investioptimal representation of documents and queries considering both root-based ased text representations. st of this paper is organized as follows. Section 2 describes Amharic language rphology. Section 3 discusses related work. In Section 4, we present the proharic IR system architecture along with various options to represent Amharic and queries. Section 5 presents the evaluation framework of the proposed dhoc retrieval system including the presentation of the resources and corpora, tal setup, and experimental results. In Section 6, we present our conclusion rward further research directions.

c Language ic Writing System

ric is the working language of the government of Ethiopia currently having an population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken guage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in mharic is the lingua franca and the most literary language serving as a mestruction in the education system of the country for a long period. Amharic pic alphabet and has 34 base characters along with modifications on the rease characters. The alphabet is conveniently written in a tabular format of mns. The first column represents the basic form with vowel ኧ /ə/ and the other represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ , ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ns such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface . It also borrows some punctuation marks such as '?' and '!' from Latin alphagh Ethiopic alphabet has numeral system, the Arabic numeral system is rather only used by Amharic. ic Morphology ric has complex morphology where many words could be generated through l and derivational processes from other word forms. Many surface forms of be formed from a base form through complex affixation, reduplication, and m interdigitation. Amharic words can be marked for a number of functions. le, a verb can be marked for a combination of person, case, gender, number, ct, and mood. An Amharic word might take up to four prefixes and five suf-. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is d from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / son singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural ker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands an be gener-ated from an Amharic root or its stems by changing the shape of in a stem or root, inserting vowels between root radicals, reduplicating one of ters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are tem templates for verbal words. However, all variants have a single root tion template. The major-ity of words in the language are generated from verbal ns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of 'killers'/ and /m t The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually ' r The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually a 'end'/ are presented as follows.

_ _ _ _ _ _ _ j _god 3 of 29
he unavailability of full-fledged low-level Amharic NLP tools makes it annotated corpus automatically. Moreover, there is lack of standard n making it a major impediment to the development of Amharic IR and jective of this research work is: (1) to promote publicly accessible Amcluding a standard test collection for IR, morphologically annotated iled stopwords list; and (2) to design Amharic IR system by investirepresentation of documents and queries considering both root-based xt representations. is paper is organized as follows. Section 2 describes Amharic language y. Section 3 discusses related work. In Section 4, we present the prosystem architecture along with various options to represent Amharic ueries. Section 5 presents the evaluation framework of the proposed rieval system including the presentation of the resources and corpora, p, and experimental results. In Section 6, we present our conclusion rther research directions.

age

g System e working language of the government of Ethiopia currently having an ion of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken n the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in is the lingua franca and the most literary language serving as a men in the education system of the country for a long period. Amharic abet and has 34 base characters along with modifications on the reracters. The alphabet is conveniently written in a tabular format of e first column represents the basic form with vowel ኧ /ə/ and the other t modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ example, the base character በ /bə/ has the following modifications: ቡ ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface borrows some punctuation marks such as '?' and '!' from Latin alphaopic alphabet has numeral system, the Arabic numeral system is rather sed by Amharic. ology complex morphology where many words could be generated through erivational processes from other word forms. Many surface forms of ed from a base form through complex affixation, reduplication, and digitation. Amharic words can be marked for a number of functions. rb can be marked for a combination of person, case, gender, number, mood. An Amharic word might take up to four prefixes and five sufexample, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ cipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands ener-ated from an Amharic root or its stems by changing the shape of or root, inserting vowels between root radicals, reduplicating one of

_ 3 of 29
vailability of full-fledged low-level Amharic NLP tools makes it ted corpus automatically. Moreover, there is lack of standard g it a major impediment to the development of Amharic IR and of this research work is: (1) to promote publicly accessible Ama standard test collection for IR, morphologically annotated opwords list; and (2) to design Amharic IR system by investientation of documents and queries considering both root-based sentations. r is organized as follows. Section 2 describes Amharic language ion 3 discusses related work. In Section 4, we present the proarchitecture along with various options to represent Amharic Section 5 presents the evaluation framework of the proposed ystem including the presentation of the resources and corpora, experimental results. In Section 6, we present our conclusion esearch directions. m ing language of the government of Ethiopia currently having an over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken orld after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in lingua franca and the most literary language serving as a mee education system of the country for a long period. Amharic nd has 34 base characters along with modifications on the re-

The alphabet is conveniently written in a tabular format of column represents the basic form with vowel ኧ /ə/ and the t modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔo/. For example, the base character በ /bə/ has the following /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are h as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), lon), etc. It also borrows some punctuation marks such as '?' The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are 3 of 29 n scope. The unavailability of full-fledged low-level Amharic NLP tools makes it to create annotated corpus automatically. Moreover, there is lack of standard e collection making it a major impediment to the development of Amharic IR and ls. The objective of this research work is: (1) to promote publicly accessible Amources including a standard test collection for IR, morphologically annotated and compiled stopwords list; and (2) to design Amharic IR system by investie optimal representation of documents and queries considering both root-based -based text representations. rest of this paper is organized as follows. Section 2 describes Amharic language orphology. Section 3 discusses related work. In Section 4, we present the promharic IR system architecture along with various options to represent Amharic nts and queries. Section 5 presents the evaluation framework of the proposed adhoc retrieval system including the presentation of the resources and corpora, ental setup, and experimental results. In Section 6, we present our conclusion forward further research directions.

ric Language aric Writing System haric is the working language of the government of Ethiopia currently having an d population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken anguage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in , Amharic is the lingua franca and the most literary language serving as a meinstruction in the education system of the country for a long period. Amharic iopic alphabet and has 34 base characters along with modifications on the rebase characters. The alphabet is conveniently written in a tabular format of lumns. The first column represents the basic form with vowel ኧ /ə/ and the other s represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own tions such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface tc. It also borrows some punctuation marks such as '?' and '!' from Latin alphaough Ethiopic alphabet has numeral system, the Arabic numeral system is rather monly used by Amharic. aric Morphology haric has complex morphology where many words could be generated through nal and derivational processes from other word forms. Many surface forms of an be formed from a base form through complex affixation, reduplication, and stem interdigitation. Amharic words can be marked for a number of functions.

ple, a verb can be marked for a combination of person, case, gender, number, pect, and mood. An Amharic word might take up to four prefixes and five suf-8]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ted from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ e/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / erson singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural arker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands s can be gener-ated from an Amharic root or its stems by changing the shape of rs in a stem or root, inserting vowels between root radicals, reduplicating one of The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language 2.1. Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language 2.1. Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language 2.1. Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are ' r s The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language 2.1. Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?'

ija [gen]-[stem]-[pal]-[p] [stem]-[pal]-[p] [inf ]-[stem]-[pal]
Appl. Sci. 2022, 12, 1294 9 of 28

Root-Based Morphological Analysis

Roots are the bases for the formation of verbal stems and many Amharic words as the origin of verbs and words derived from the verbal stems is root. Stem and root have the same form for primary nouns, adjectives, adverbs, and functional words. For Amharic nouns, adjectives, and adverbs derived directly from verbal roots and stems, we proposed the roots of their corresponding verbs as index and query terms. For example, the morphological analysis of the verb /k s b r such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually kwat spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually w such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually ma 'if I break them even'/ and the derived noun /s /, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters ch as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own nctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface lon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphat. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather ost commonly used by Amharic.

. Amharic Morphology

Amharic has complex morphology where many words could be generated through flectional and derivational processes from other word forms. Many surface forms of ords can be formed from a base form through complex affixation, reduplication, and mitic stem interdigitation. Amharic words can be marked for a number of functions. r example, a verb can be marked for a combination of person, case, gender, number, nse, aspect, and mood. An Amharic word might take up to four prefixes and five sufes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is nstructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ usative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural ject marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands words can be gener-ated from an Amharic root or its stems by changing the shape of aracters in a stem or root, inserting vowels between root radicals, reduplicating one of e characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are ultiple stem templates for verbal words. However, all variants have a single root presentation template. The major-ity of words in the language are generated from verbal ots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of ords from verbal roots usually b bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters uch as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own unctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface olon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphaet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather ost commonly used by Amharic.

.2. Amharic Morphology

Amharic has complex morphology where many words could be generated through nflectional and derivational processes from other word forms. Many surface forms of ords can be formed from a base form through complex affixation, reduplication, and emitic stem interdigitation. Amharic words can be marked for a number of functions. or example, a verb can be marked for a combination of person, case, gender, number, ense, aspect, and mood. An Amharic word might take up to four prefixes and five sufixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is onstructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ausative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / u first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural bject marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands f words can be gener-ated from an Amharic root or its stems by changing the shape of haracters in a stem or root, inserting vowels between root radicals, reduplicating one of he characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are ultiple stem templates for verbal words. However, all variants have a single root epresentation template. The major-ity of words in the language are generated from verbal oots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of ords from verbal roots usually rate 'my state of being broken'/ are presented below.

_ _ _ _ _ _ k _s b r
aracters. The alphabet is conveniently written in a tabular format of he first column represents the basic form with vowel ኧ /ə/ and the other ent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ r example, the base character በ /bə/ has the following modifications: ቡ /, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ch as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface o borrows some punctuation marks such as '?' and '!' from Latin alphahiopic alphabet has numeral system, the Arabic numeral system is rather used by Amharic. phology s complex morphology where many words could be generated through derivational processes from other word forms. Many surface forms of rmed from a base form through complex affixation, reduplication, and erdigitation. Amharic words can be marked for a number of functions. erb can be marked for a combination of person, case, gender, number, d mood. An Amharic word might take up to four prefixes and five sufexample, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ngular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural r per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands gener-ated from an Amharic root or its stems by changing the shape of tem or root, inserting vowels between root radicals, reduplicating one of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are emplates for verbal words. However, all variants have a single root mplate. The major-ity of words in the language are generated from verbal jectives, and ad-verbs can be derived from verbal roots. The derivation of al roots usually _ku_ epresentations. aper is organized as follows. Section 2 describes Amharic language Section 3 discusses related work. In Section 4, we present the prostem architecture along with various options to represent Amharic ies. Section 5 presents the evaluation framework of the proposed al system including the presentation of the resources and corpora, and experimental results. In Section 6, we present our conclusion er research directions. ystem orking language of the government of Ethiopia currently having an of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken he world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in the lingua franca and the most literary language serving as a men the education system of the country for a long period. Amharic et and has 34 base characters along with modifications on the reters. The alphabet is conveniently written in a tabular format of first column represents the basic form with vowel ኧ /ə/ and the sent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ኦ /ʔo/. For example, the base character በ /bə/ has the following , ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), e colon), etc. It also borrows some punctuation marks such as '?' ha-bet. Although Ethiopic alphabet has numeral system, the Arabic her most commonly used by Amharic. gy plex morphology where many words could be generated through ational processes from other word forms. Many surface forms of from a base form through complex affixation, reduplication, and itation. Amharic words can be marked for a number of functions. can be marked for a combination of person, case, gender, number, od. An Amharic word might take up to four prefixes and five sufe, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciproerb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular rfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perusative/, and ና /na conjunction/). Thousands of words can be generc root or its stems by changing the shape of characters in a stem or between root radicals, reduplicating one of the characters of the stem adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for er, all variants have a single root representation template. The majornguage are generated from verbal roots. Nouns, adjectives, and adfrom verbal roots. The derivation of words from verbal roots usually t Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually w ive base characters. The alphabet is conveniently written in a tabular format of columns. The first column represents the basic form with vowel ኧ /ə/ and the other rders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ nd ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own tuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface ), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphalthough Ethiopic alphabet has numeral system, the Arabic numeral system is rather commonly used by Amharic.

mharic Morphology

Amharic has complex morphology where many words could be generated through tional and derivational processes from other word forms. Many surface forms of s can be formed from a base form through complex affixation, reduplication, and tic stem interdigitation. Amharic words can be marked for a number of functions. xample, a verb can be marked for a combination of person, case, gender, number, , aspect, and mood. An Amharic word might take up to four prefixes and five suf- [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ tive/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / st person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural t marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands ords can be gener-ated from an Amharic root or its stems by changing the shape of cters in a stem or root, inserting vowels between root radicals, reduplicating one of haracters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are iple stem templates for verbal words. However, all variants have a single root sentation template. The major-ity of words in the language are generated from verbal . Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of s from verbal roots usually _ ed text representations. of this paper is organized as follows. Section 2 describes Amharic language hology. Section 3 discusses related work. In Section 4, we present the proric IR system architecture along with various options to represent Amharic nd queries. Section 5 presents the evaluation framework of the proposed oc retrieval system including the presentation of the resources and corpora, setup, and experimental results. In Section 6, we present our conclusion ard further research directions.

anguage riting System c is the working language of the government of Ethiopia currently having an pulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken age in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in haric is the lingua franca and the most literary language serving as a meruction in the education system of the country for a long period. Amharic c alphabet and has 34 base characters along with modifications on the ree characters. The alphabet is conveniently written in a tabular format of ns. The first column represents the basic form with vowel ኧ /ə/ and the ers represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following s: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are aracters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), ' (preface colon), etc. It also borrows some punctuation marks such as '?' atin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic em is rather most commonly used by Amharic. orphology c has complex morphology where many words could be generated through nd derivational processes from other word forms. Many surface forms of e formed from a base form through complex affixation, reduplication, and interdigitation. Amharic words can be marked for a number of functions. , a verb can be marked for a combination of person, case, gender, number, , and mood. An Amharic word might take up to four prefixes and five sufr example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed efixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprofective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular er for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-Amharic root or its stems by changing the shape of characters in a stem or vowels between root radicals, reduplicating one of the characters of the stem f, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for . However, all variants have a single root representation template. The majorin the language are generated from verbal roots. Nouns, adjectives, and adderived from verbal roots. The derivation of words from verbal roots usually ective base characters. The alphabet is conveniently written in a tabular format of ven columns. The first column represents the basic form with vowel ኧ /ə/ and the other orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ u/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters ch as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own nctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface lon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphat. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather ost commonly used by Amharic.

. Amharic Morphology

Amharic has complex morphology where many words could be generated through flectional and derivational processes from other word forms. Many surface forms of ords can be formed from a base form through complex affixation, reduplication, and mitic stem interdigitation. Amharic words can be marked for a number of functions. r example, a verb can be marked for a combination of person, case, gender, number, nse, aspect, and mood. An Amharic word might take up to four prefixes and five sufes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is nstructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ usative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural ject marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands words can be gener-ated from an Amharic root or its stems by changing the shape of aracters in a stem or root, inserting vowels between root radicals, reduplicating one of e characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are ultiple stem templates for verbal words. However, all variants have a single root presentation template. The major-ity of words in the language are generated from verbal ots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of ords from verbal roots usually ma s spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually b spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually r spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually _ and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually t spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually _ and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually

e [pre]-[stem]-[1,s]-[3,p]-[foc] [stem]-[nom]-[1,s] _ --_ _ _ --_ _ [pre]-[root]-[1,s]-[3,p]-[foc] [root]-[nom]-[1,s,pos]
Adjectives derived from primary nouns are represented using the root of the corresponding nouns. Nouns derived from primary adjectives are also represented using the root of the corresponding adjectives. The root representation of primary nouns, adjectives, adverbs and functional words is different from verbal root representation. For example, the root of the noun /m kinawa 'her car'/, /d gag 2. Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually 'generous'/, and /lelot

The rest of this paper is organized as follows. Section 2 describes Amharic lang and its morphology. Section 3 discusses related work. In Section 4, we present the posed Amharic IR system architecture along with various options to represent Am documents and queries. Section 5 presents the evaluation framework of the prop Amharic adhoc retrieval system including the presentation of the resources and cor experimental setup, and experimental results. In Section 6, we present our concl and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently havi estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly sp Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spok Ethiopia, Amharic is the lingua franca and the most literary language serving as dium of instruction in the education system of the country for a long period. Am uses Ethiopic alphabet and has 34 base characters along with modifications on th spective base characters. The alphabet is conveniently written in a tabular form seven columns. The first column represents the basic form with vowel ኧ /ə/ and the six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modificatio /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized chara such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (pr colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin a bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is r most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated thr inflectional and derivational processes from other word forms. Many surface form words can be formed from a base form through complex affixation, reduplication Semitic stem interdigitation. Amharic words can be marked for a number of func For example, a verb can be marked for a combination of person, case, gender, nu tense, aspect, and mood. An Amharic word might take up to four prefixes and fiv fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨ constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causa ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural o marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousan words can be gener-ated from an Amharic root or its stems by changing the sha characters in a stem or root, inserting vowels between root radicals, reduplicating o the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. The multiple stem templates for verbal words. However, all variants have a single representation template. The major-ity of words in the language are generated from v roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivat words from verbal roots usually

2.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia curre estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most com Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages Ethiopia, Amharic is the lingua franca and the most literary language se dium of instruction in the education system of the country for a long pe uses Ethiopic alphabet and has 34 base characters along with modificati spective base characters. The alphabet is conveniently written in a tab seven columns. The first column represents the basic form with vowel ኧ /ə six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following m /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labiali such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language ha punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon colon), etc. It also borrows some punctuation marks such as '?' and '!' from bet. Although Ethiopic alphabet has numeral system, the Arabic numeral s most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be gene inflectional and derivational processes from other word forms. Many su words can be formed from a base form through complex affixation, redu Semitic stem interdigitation. Amharic words can be marked for a numbe For example, a verb can be marked for a combination of person, case, ge tense, aspect, and mood. An Amharic word might take up to four prefixe fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkw constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ nega causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and fou ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunctio of words can be gener-ated from an Amharic root or its stems by changin characters in a stem or root, inserting vowels between root radicals, redup the characters of the stem or word itself, and by adding affixes on stems multiple stem templates for verbal words. However, all variants have representation template. The major-ity of words in the language are generat roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. Th words from verbal roots usually 'others'/ are /m kina/, /d g 2. Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually /, and /lela/, respectively. However, the root of the verbals such as /m l and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually s and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually 'answer'/ and /r Z and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually m and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually 'long'/ are --/m-s-l/ and --/r-z-m/, respectively. The reduced form of some variants of a verb is represented by the corresponding radical form. For instance, the root of the verb /mot 'he died'/ and /nor 'he lived'/ are --and --, respectively. Morphological variants of Amharic words, especially verbs can have more than one stem, but still a common root. All variants of an Amharic verb can thus be represented by a single root during indexing. On the other hand, semantically unrelated words hardly ever have a common root. To sum up, basic stem text representation is robust to represent primary noun, adjectives and adverbs, and functional words whereas root is robust to represent all types of words, including verbs.

Amharic Stopword Identification and Removal

One of the major preprocessing tasks in IR and many other text processing applications is stopword removal. Accordingly, stopword lists have been constructed for many languages. However, standard stopword list is unavailable for Amharic IR yet. The common trend for identifying and removing stopwords is to do it before applying morphological analysis on words in a text. This is also what has been carried out in the previous Amharic IR studies. We think this is an inappropriate way to consider stopwords for Amharic. Some Amharic stopwords do not necessarily exist as standalone words and others may appear with other words as prefix and suffix. For example, 'the' is usually considered as a stopword in English; its Amharic equivalent is a suffix '-/- The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-u/' or '-/-w Appl. Sci. 2022, 12, x FOR PEER REVIEW 3 of limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes difficult to create annotated corpus automatically. Moreover, there is lack of standa reference collection making it a major impediment to the development of Amharic IR an NLP tools. The objective of this research work is: (1) to promote publicly accessible Am haric resources including a standard test collection for IR, morphologically annotate corpora and compiled stopwords list; and (2) to design Amharic IR system by inves gating the optimal representation of documents and queries considering both root-base and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic langua and its morphology. Section 3 discusses related work. In Section 4, we present the pr posed Amharic IR system architecture along with various options to represent Amhar documents and queries. Section 5 presents the evaluation framework of the propose Amharic adhoc retrieval system including the presentation of the resources and corpor experimental setup, and experimental results. In Section 6, we present our conclusio and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having a estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spok Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken Ethiopia, Amharic is the lingua franca and the most literary language serving as a m dium of instruction in the education system of the country for a long period. Amhar uses Ethiopic alphabet and has 34 base characters along with modifications on the r spective base characters. The alphabet is conveniently written in a tabular format seven columns. The first column represents the basic form with vowel ኧ /ə/ and the oth six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characte such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its ow punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (prefa colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alph bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rath most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated throug inflectional and derivational processes from other word forms. Many surface forms words can be formed from a base form through complex affixation, reduplication, an Semitic stem interdigitation. Amharic words can be marked for a number of function For example, a verb can be marked for a combination of person, case, gender, numbe tense, aspect, and mood. An Amharic word might take up to four prefixes and five su fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plur object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousan of words can be gener-ated from an Amharic root or its stems by changing the shape characters in a stem or root, inserting vowels between root radicals, reduplicating one the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There a multiple stem templates for verbal words. However, all variants have a single ro representation template. The major-ity of words in the language are generated from verb roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation words from verbal roots usually /' that does not appear as a standalone word. Accordingly, 'the house' and 'the student', for instance, are equivalent to ' /bet VIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually /+ -/- The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-u/' → ' /betu/' and ' /t mari/+ -/-w Appl. Sci. 2022, 12, x FOR PEER REVIEW limited in scope. The unavailability of full-fledged low-level Amharic NLP tools difficult to create annotated corpus automatically. Moreover, there is lack of reference collection making it a major impediment to the development of Amhar NLP tools. The objective of this research work is: (1) to promote publicly access haric resources including a standard test collection for IR, morphologically a corpora and compiled stopwords list; and (2) to design Amharic IR system b gating the optimal representation of documents and queries considering both ro and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic and its morphology. Section 3 discusses related work. In Section 4, we present posed Amharic IR system architecture along with various options to represent documents and queries. Section 5 presents the evaluation framework of the Amharic adhoc retrieval system including the presentation of the resources and experimental setup, and experimental results. In Section 6, we present our co and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently h estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonl Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are s Ethiopia, Amharic is the lingua franca and the most literary language serving dium of instruction in the education system of the country for a long period. uses Ethiopic alphabet and has 34 base characters along with modifications o spective base characters. The alphabet is conveniently written in a tabular f seven columns. The first column represents the basic form with vowel ኧ /ə/ and six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modific /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized c such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has als punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' colon), etc. It also borrows some punctuation marks such as '?' and '!' from Lat bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated inflectional and derivational processes from other word forms. Many surface words can be formed from a base form through complex affixation, reduplica Semitic stem interdigitation. Amharic words can be marked for a number of f For example, a verb can be marked for a combination of person, case, gender, tense, aspect, and mood. An Amharic word might take up to four prefixes and fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəw constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suf ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third pers object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). T of words can be gener-ated from an Amharic root or its stems by changing the characters in a stem or root, inserting vowels between root radicals, reduplicati the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. multiple stem templates for verbal words. However, all variants have a si representation template. The major-ity of words in the language are generated fro roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The der words from verbal roots usually

/' → ' /t mariw 3 of 29
scope. The unavailability of full-fledged low-level Amharic NLP tools makes it to create annotated corpus automatically. Moreover, there is lack of standard collection making it a major impediment to the development of Amharic IR and s. The objective of this research work is: (1) to promote publicly accessible Amources including a standard test collection for IR, morphologically annotated nd compiled stopwords list; and (2) to design Amharic IR system by investie optimal representation of documents and queries considering both root-based -based text representations. rest of this paper is organized as follows. Section 2 describes Amharic language orphology. Section 3 discusses related work. In Section 4, we present the proharic IR system architecture along with various options to represent Amharic ts and queries. Section 5 presents the evaluation framework of the proposed adhoc retrieval system including the presentation of the resources and corpora, ntal setup, and experimental results. In Section 6, we present our conclusion orward further research directions.

ic Language ric Writing System aric is the working language of the government of Ethiopia currently having an population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken nguage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Amharic is the lingua franca and the most literary language serving as a meinstruction in the education system of the country for a long period. Amharic opic alphabet and has 34 base characters along with modifications on the rebase characters. The alphabet is conveniently written in a tabular format of umns. The first column represents the basic form with vowel ኧ /ə/ and the other s represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ i/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ions such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface c. It also borrows some punctuation marks such as '?' and '!' from Latin alphaugh Ethiopic alphabet has numeral system, the Arabic numeral system is rather monly used by Amharic.

ric Morphology aric has complex morphology where many words could be generated through al and derivational processes from other word forms. Many surface forms of n be formed from a base form through complex affixation, reduplication, and tem interdigitation. Amharic words can be marked for a number of functions. ple, a verb can be marked for a combination of person, case, gender, number, ect, and mood. An Amharic word might take up to four prefixes and five suf-]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ /, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / erson singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural rker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands can be gener-ated from an Amharic root or its stems by changing the shape of s in a stem or root, inserting vowels between root radicals, reduplicating one of cters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are stem templates for verbal words. However, all variants have a single root ation template. The major-ity of words in the language are generated from verbal uns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of m verbal roots usually /', respectively. Terms can appear in various morphological structures as there can be several sequences of affixes representing articles, prepositions, numbers, etc. For instance, the stopword /w R PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually t'

x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic lan and its morphology. Section 3 discusses related work. In Section 4, we present th posed Amharic IR system architecture along with various options to represent Am documents and queries. Section 5 presents the evaluation framework of the pro Amharic adhoc retrieval system including the presentation of the resources and co experimental setup, and experimental results. In Section 6, we present our conc and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently hav estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly s Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spo Ethiopia, Amharic is the lingua franca and the most literary language serving as dium of instruction in the education system of the country for a long period. Am uses Ethiopic alphabet and has 34 base characters along with modifications on spective base characters. The alphabet is conveniently written in a tabular form seven columns. The first column represents the basic form with vowel ኧ /ə/ and the six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modificati /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized cha such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also it punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (p colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated th inflectional and derivational processes from other word forms. Many surface fo words can be formed from a base form through complex affixation, reduplicatio Semitic stem interdigitation. Amharic words can be marked for a number of fun For example, a verb can be marked for a combination of person, case, gender, nu tense, aspect, and mood. An Amharic word might take up to four prefixes and fiv fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨ constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffix ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thou of words can be gener-ated from an Amharic root or its stems by changing the sh characters in a stem or root, inserting vowels between root radicals, reduplicating the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. The multiple stem templates for verbal words. However, all variants have a singl representation template. The major-ity of words in the language are generated from roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The deriva words from verbal roots usually s Appl. Sci. 2022, 12, x FOR PEER REVIEW limited in scope. The unavailability of full-fledged low-level Amharic NLP tools m difficult to create annotated corpus automatically. Moreover, there is lack of s reference collection making it a major impediment to the development of Amhari NLP tools. The objective of this research work is: (1) to promote publicly accessi haric resources including a standard test collection for IR, morphologically an corpora and compiled stopwords list; and (2) to design Amharic IR system by gating the optimal representation of documents and queries considering both roo and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic la and its morphology. Section 3 discusses related work. In Section 4, we present posed Amharic IR system architecture along with various options to represent A documents and queries. Section 5 presents the evaluation framework of the p Amharic adhoc retrieval system including the presentation of the resources and experimental setup, and experimental results. In Section 6, we present our con and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently ha estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are sp Ethiopia, Amharic is the lingua franca and the most literary language serving a dium of instruction in the education system of the country for a long period. A uses Ethiopic alphabet and has 34 base characters along with modifications on spective base characters. The alphabet is conveniently written in a tabular fo seven columns. The first column represents the basic form with vowel ኧ /ə/ and t six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifica /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized ch such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' colon), etc. It also borrows some punctuation marks such as '?' and '!' from Lati bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated inflectional and derivational processes from other word forms. Many surface f words can be formed from a base form through complex affixation, reduplicati Semitic stem interdigitation. Amharic words can be marked for a number of fu For example, a verb can be marked for a combination of person, case, gender, n tense, aspect, and mood. An Amharic word might take up to four prefixes and fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨn constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffi ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third perso object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Th of words can be gener-ated from an Amharic root or its stems by changing the s characters in a stem or root, inserting vowels between root radicals, reduplicatin the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. T multiple stem templates for verbal words. However, all variants have a sin representation template. The major-ity of words in the language are generated from roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The deriv words from verbal roots usually t'awi/, /w 3 of 29 e. The unavailability of full-fledged low-level Amharic NLP tools makes it ate annotated corpus automatically. Moreover, there is lack of standard tion making it a major impediment to the development of Amharic IR and objective of this research work is: (1) to promote publicly accessible Amincluding a standard test collection for IR, morphologically annotated mpiled stopwords list; and (2) to design Amharic IR system by investimal representation of documents and queries considering both root-based text representations. f this paper is organized as follows. Section 2 describes Amharic language logy. Section 3 discusses related work. In Section 4, we present the pro-IR system architecture along with various options to represent Amharic queries. Section 5 presents the evaluation framework of the proposed retrieval system including the presentation of the resources and corpora, etup, and experimental results. In Section 6, we present our conclusion d further research directions.

guage riting System

s the working language of the government of Ethiopia currently having an lation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken ge in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in aric is the lingua franca and the most literary language serving as a mection in the education system of the country for a long period. Amharic lphabet and has 34 base characters along with modifications on the recharacters. The alphabet is conveniently written in a tabular format of . The first column represents the basic form with vowel ኧ /ə/ and the other sent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ For example, the base character በ /bə/ has the following modifications: ቡ a/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own uch as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface lso borrows some punctuation marks such as '?' and '!' from Latin alphathiopic alphabet has numeral system, the Arabic numeral system is rather y used by Amharic.

orphology as complex morphology where many words could be generated through derivational processes from other word forms. Many surface forms of ormed from a base form through complex affixation, reduplication, and terdigitation. Amharic words can be marked for a number of functions. verb can be marked for a combination of person, case, gender, number, nd mood. An Amharic word might take up to four prefixes and five sufr example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is m four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands e gener-ated from an Amharic root or its stems by changing the shape of stem or root, inserting vowels between root radicals, reduplicating one of of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root template. The major-ity of words in the language are generated from verbal djectives, and ad-verbs can be derived from verbal roots. The derivation of bal roots usually s 3 of 29 pe. The unavailability of full-fledged low-level Amharic NLP tools makes it eate annotated corpus automatically. Moreover, there is lack of standard ection making it a major impediment to the development of Amharic IR and e objective of this research work is: (1) to promote publicly accessible Ames including a standard test collection for IR, morphologically annotated compiled stopwords list; and (2) to design Amharic IR system by investitimal representation of documents and queries considering both root-based ed text representations. of this paper is organized as follows. Section 2 describes Amharic language hology. Section 3 discusses related work. In Section 4, we present the proic IR system architecture along with various options to represent Amharic nd queries. Section 5 presents the evaluation framework of the proposed c retrieval system including the presentation of the resources and corpora, setup, and experimental results. In Section 6, we present our conclusion ard further research directions.

anguage riting System

is the working language of the government of Ethiopia currently having an pulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken age in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in haric is the lingua franca and the most literary language serving as a meuction in the education system of the country for a long period. Amharic alphabet and has 34 base characters along with modifications on the recharacters. The alphabet is conveniently written in a tabular format of s. The first column represents the basic form with vowel ኧ /ə/ and the other resent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ . For example, the base character በ /bə/ has the following modifications: ቡ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters a/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface also borrows some punctuation marks such as '?' and '!' from Latin alpha-Ethiopic alphabet has numeral system, the Arabic numeral system is rather ly used by Amharic. orphology has complex morphology where many words could be generated through nd derivational processes from other word forms. Many surface forms of formed from a base form through complex affixation, reduplication, and interdigitation. Amharic words can be marked for a number of functions. a verb can be marked for a combination of person, case, gender, number, and mood. An Amharic word might take up to four prefixes and five suf-For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is rom four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands be gener-ated from an Amharic root or its stems by changing the shape of a stem or root, inserting vowels between root radicals, reduplicating one of of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root template. The major-ity of words in the language are generated from verbal adjectives, and ad-verbs can be derived from verbal roots. The derivation of erbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually 3 of 29 n scope. The unavailability of full-fledged low-level Amharic NLP tools makes it to create annotated corpus automatically. Moreover, there is lack of standard e collection making it a major impediment to the development of Amharic IR and ls. The objective of this research work is: (1) to promote publicly accessible Amsources including a standard test collection for IR, morphologically annotated and compiled stopwords list; and (2) to design Amharic IR system by investie optimal representation of documents and queries considering both root-based -based text representations. rest of this paper is organized as follows. Section 2 describes Amharic language orphology. Section 3 discusses related work. In Section 4, we present the promharic IR system architecture along with various options to represent Amharic nts and queries. Section 5 presents the evaluation framework of the proposed adhoc retrieval system including the presentation of the resources and corpora, ental setup, and experimental results. In Section 6, we present our conclusion forward further research directions. ric Language aric Writing System haric is the working language of the government of Ethiopia currently having an d population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in , Amharic is the lingua franca and the most literary language serving as a meinstruction in the education system of the country for a long period. Amharic iopic alphabet and has 34 base characters along with modifications on the rebase characters. The alphabet is conveniently written in a tabular format of lumns. The first column represents the basic form with vowel ኧ /ə/ and the other rs represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own tions such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface tc. It also borrows some punctuation marks such as '?' and '!' from Latin alphaough Ethiopic alphabet has numeral system, the Arabic numeral system is rather monly used by Amharic.

aric Morphology haric has complex morphology where many words could be generated through nal and derivational processes from other word forms. Many surface forms of an be formed from a base form through complex affixation, reduplication, and stem interdigitation. Amharic words can be marked for a number of functions.

ple, a verb can be marked for a combination of person, case, gender, number, pect, and mood. An Amharic word might take up to four prefixes and five suf-8]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ted from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ e/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / erson singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural arker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands s can be gener-ated from an Amharic root or its stems by changing the shape of rs in a stem or root, inserting vowels between root radicals, reduplicating one of acters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are stem templates for verbal words. However, all variants have a single root tation template. The major-ity of words in the language are generated from verbal ouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of om verbal roots usually n 3 of 29 in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it lt to create annotated corpus automatically. Moreover, there is lack of standard ce collection making it a major impediment to the development of Amharic IR and ools. The objective of this research work is: (1) to promote publicly accessible Amresources including a standard test collection for IR, morphologically annotated a and compiled stopwords list; and (2) to design Amharic IR system by investithe optimal representation of documents and queries considering both root-based em-based text representations. he rest of this paper is organized as follows. Section 2 describes Amharic language s morphology. Section 3 discusses related work. In Section 4, we present the pro-Amharic IR system architecture along with various options to represent Amharic ents and queries. Section 5 presents the evaluation framework of the proposed ric adhoc retrieval system including the presentation of the resources and corpora, mental setup, and experimental results. In Section 6, we present our conclusion t forward further research directions.

haric Language haric Writing System mharic is the working language of the government of Ethiopia currently having an ted population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken c language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in ia, Amharic is the lingua franca and the most literary language serving as a meof instruction in the education system of the country for a long period. Amharic thiopic alphabet and has 34 base characters along with modifications on the ree base characters. The alphabet is conveniently written in a tabular format of columns. The first column represents the basic form with vowel ኧ /ə/ and the other ers represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ d ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters s ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface , etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphathough Ethiopic alphabet has numeral system, the Arabic numeral system is rather ommonly used by Amharic.

haric Morphology mharic has complex morphology where many words could be generated through ional and derivational processes from other word forms. Many surface forms of can be formed from a base form through complex affixation, reduplication, and c stem interdigitation. Amharic words can be marked for a number of functions. ample, a verb can be marked for a combination of person, case, gender, number, aspect, and mood. An Amharic word might take up to four prefixes and five suf- [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ucted from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ive/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / t person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands ds can be gener-ated from an Amharic root or its stems by changing the shape of ters in a stem or root, inserting vowels between root radicals, reduplicating one of aracters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are le stem templates for verbal words. However, all variants have a single root entation template. The major-ity of words in the language are generated from verbal Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic and its morphology. Section 3 discusses related work. In Section 4, we present posed Amharic IR system architecture along with various options to represent documents and queries. Section 5 presents the evaluation framework of the Amharic adhoc retrieval system including the presentation of the resources and experimental setup, and experimental results. In Section 6, we present our co and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently h estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonl Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are s Ethiopia, Amharic is the lingua franca and the most literary language serving dium of instruction in the education system of the country for a long period. uses Ethiopic alphabet and has 34 base characters along with modifications o spective base characters. The alphabet is conveniently written in a tabular f seven columns. The first column represents the basic form with vowel ኧ /ə/ and six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modific /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized c such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has als punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' colon), etc. It also borrows some punctuation marks such as '?' and '!' from Lat bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated inflectional and derivational processes from other word forms. Many surface words can be formed from a base form through complex affixation, reduplica Semitic stem interdigitation. Amharic words can be marked for a number of f For example, a verb can be marked for a combination of person, case, gender, tense, aspect, and mood. An Amharic word might take up to four prefixes and fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəw constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suf ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third pers object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). T of words can be gener-ated from an Amharic root or its stems by changing the characters in a stem or root, inserting vowels between root radicals, reduplicati the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. multiple stem templates for verbal words. However, all variants have a si representation template. The major-ity of words in the language are generated fro roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The der words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amhari and its morphology. Section 3 discusses related work. In Section 4, we prese posed Amharic IR system architecture along with various options to represen documents and queries. Section 5 presents the evaluation framework of the Amharic adhoc retrieval system including the presentation of the resources an experimental setup, and experimental results. In Section 6, we present our and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most common Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are Ethiopia, Amharic is the lingua franca and the most literary language servin dium of instruction in the education system of the country for a long period uses Ethiopic alphabet and has 34 base characters along with modifications spective base characters. The alphabet is conveniently written in a tabular seven columns. The first column represents the basic form with vowel ኧ /ə/ an six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modif /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has a punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), ' colon), etc. It also borrows some punctuation marks such as '?' and '!' from L bet. Although Ethiopic alphabet has numeral system, the Arabic numeral syste most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generate inflectional and derivational processes from other word forms. Many surfac words can be formed from a base form through complex affixation, reduplic Semitic stem interdigitation. Amharic words can be marked for a number of For example, a verb can be marked for a combination of person, case, gende tense, aspect, and mood. An Amharic word might take up to four prefixes an fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃə constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four su ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third pe object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). of words can be gener-ated from an Amharic root or its stems by changing th characters in a stem or root, inserting vowels between root radicals, reduplica the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF] multiple stem templates for verbal words. However, all variants have a representation template. The major-ity of words in the language are generated f roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The de words from verbal roots usually t'

Appl. Sci. 2022, 12, x FOR PEER REVIEW limited in scope. The unavailability of full-fledged low-level Amharic NLP t difficult to create annotated corpus automatically. Moreover, there is lack reference collection making it a major impediment to the development of Am NLP tools. The objective of this research work is: (1) to promote publicly ac haric resources including a standard test collection for IR, morphological corpora and compiled stopwords list; and (2) to design Amharic IR system gating the optimal representation of documents and queries considering bot and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amha and its morphology. Section 3 discusses related work. In Section 4, we pre posed Amharic IR system architecture along with various options to repres documents and queries. Section 5 presents the evaluation framework of t Amharic adhoc retrieval system including the presentation of the resources experimental setup, and experimental results. In Section 6, we present ou and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia curren estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most comm Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages a Ethiopia, Amharic is the lingua franca and the most literary language serv dium of instruction in the education system of the country for a long peri uses Ethiopic alphabet and has 34 base characters along with modificatio spective base characters. The alphabet is conveniently written in a tabul seven columns. The first column represents the basic form with vowel ኧ /ə/ six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following mod /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialize such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon) colon), etc. It also borrows some punctuation marks such as '?' and '!' from bet. Although Ethiopic alphabet has numeral system, the Arabic numeral sys most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be gener inflectional and derivational processes from other word forms. Many surf words can be formed from a base form through complex affixation, redup Semitic stem interdigitation. Amharic words can be marked for a number For example, a verb can be marked for a combination of person, case, gen tense, aspect, and mood. An Amharic word might take up to four prefixes fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwa constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negati causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third p object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/ of words can be gener-ated from an Amharic root or its stems by changing characters in a stem or root, inserting vowels between root radicals, redupli the characters of the stem or word itself, and by adding affixes on stems [2 multiple stem templates for verbal words. However, all variants have a representation template. The major-ity of words in the language are generated roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The words from verbal roots usually /, /b w 3 of 29 e. The unavailability of full-fledged low-level Amharic NLP tools makes it ate annotated corpus automatically. Moreover, there is lack of standard ction making it a major impediment to the development of Amharic IR and e objective of this research work is: (1) to promote publicly accessible Ams including a standard test collection for IR, morphologically annotated ompiled stopwords list; and (2) to design Amharic IR system by investiimal representation of documents and queries considering both root-based d text representations. f this paper is organized as follows. Section 2 describes Amharic language ology. Section 3 discusses related work. In Section 4, we present the proc IR system architecture along with various options to represent Amharic d queries. Section 5 presents the evaluation framework of the proposed retrieval system including the presentation of the resources and corpora, setup, and experimental results. In Section 6, we present our conclusion rd further research directions.

nguage riting System

is the working language of the government of Ethiopia currently having an ulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken ge in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in aric is the lingua franca and the most literary language serving as a mection in the education system of the country for a long period. Amharic alphabet and has 34 base characters along with modifications on the recharacters. The alphabet is conveniently written in a tabular format of s. The first column represents the basic form with vowel ኧ /ə/ and the other esent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ For example, the base character በ /bə/ has the following modifications: ቡ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters a/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface lso borrows some punctuation marks such as '?' and '!' from Latin alpha-Ethiopic alphabet has numeral system, the Arabic numeral system is rather ly used by Amharic. orphology has complex morphology where many words could be generated through d derivational processes from other word forms. Many surface forms of formed from a base form through complex affixation, reduplication, and nterdigitation. Amharic words can be marked for a number of functions. a verb can be marked for a combination of person, case, gender, number, and mood. An Amharic word might take up to four prefixes and five sufor example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is om four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands be gener-ated from an Amharic root or its stems by changing the shape of stem or root, inserting vowels between root radicals, reduplicating one of of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root template. The major-ity of words in the language are generated from verbal adjectives, and ad-verbs can be derived from verbal roots. The derivation of rbal roots usually of this paper is organized as follows. Section 2 describes Amharic language hology. Section 3 discusses related work. In Section 4, we present the proric IR system architecture along with various options to represent Amharic nd queries. Section 5 presents the evaluation framework of the proposed oc retrieval system including the presentation of the resources and corpora, l setup, and experimental results. In Section 6, we present our conclusion ard further research directions.

anguage

Writing System c is the working language of the government of Ethiopia currently having an pulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken uage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in haric is the lingua franca and the most literary language serving as a meruction in the education system of the country for a long period. Amharic c alphabet and has 34 base characters along with modifications on the ree characters. The alphabet is conveniently written in a tabular format of ns. The first column represents the basic form with vowel ኧ /ə/ and the other present modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /. For example, the base character በ /bə/ has the following modifications: ቡ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters wa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface t also borrows some punctuation marks such as '?' and '!' from Latin alphah Ethiopic alphabet has numeral system, the Arabic numeral system is rather nly used by Amharic.

Morphology

c has complex morphology where many words could be generated through nd derivational processes from other word forms. Many surface forms of e formed from a base form through complex affixation, reduplication, and interdigitation. Amharic words can be marked for a number of functions. , a verb can be marked for a combination of person, case, gender, number, , and mood. An Amharic word might take up to four prefixes and five suf-For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / n singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural r for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands be gener-ated from an Amharic root or its stems by changing the shape of a stem or root, inserting vowels between root radicals, reduplicating one of s of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are m templates for verbal words. However, all variants have a single root n template. The major-ity of words in the language are generated from verbal , adjectives, and ad-verbs can be derived from verbal roots. The derivation of erbal roots usually t'

3 of 29 scope. The unavailability of full-fledged low-level Amharic NLP tools makes it create annotated corpus automatically. Moreover, there is lack of standard ollection making it a major impediment to the development of Amharic IR and The objective of this research work is: (1) to promote publicly accessible Amrces including a standard test collection for IR, morphologically annotated d compiled stopwords list; and (2) to design Amharic IR system by investioptimal representation of documents and queries considering both root-based ased text representations. st of this paper is organized as follows. Section 2 describes Amharic language rphology. Section 3 discusses related work. In Section 4, we present the proharic IR system architecture along with various options to represent Amharic s and queries. Section 5 presents the evaluation framework of the proposed dhoc retrieval system including the presentation of the resources and corpora, tal setup, and experimental results. In Section 6, we present our conclusion rward further research directions. c Language ic Writing System ric is the working language of the government of Ethiopia currently having an population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken guage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in mharic is the lingua franca and the most literary language serving as a mestruction in the education system of the country for a long period. Amharic pic alphabet and has 34 base characters along with modifications on the rease characters. The alphabet is conveniently written in a tabular format of mns. The first column represents the basic form with vowel ኧ /ə/ and the other represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ , ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ns such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface . It also borrows some punctuation marks such as '?' and '!' from Latin alphagh Ethiopic alphabet has numeral system, the Arabic numeral system is rather only used by Amharic.

ic Morphology ric has complex morphology where many words could be generated through l and derivational processes from other word forms. Many surface forms of be formed from a base form through complex affixation, reduplication, and m interdigitation. Amharic words can be marked for a number of functions. le, a verb can be marked for a combination of person, case, gender, number, ct, and mood. An Amharic word might take up to four prefixes and five suf-. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is d from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / son singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural ker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands an be gener-ated from an Amharic root or its stems by changing the shape of in a stem or root, inserting vowels between root radicals, reduplicating one of ters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are tem templates for verbal words. However, all variants have a single root tion template. The major-ity of words in the language are generated from verbal ns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually na/, etc. Furthermore, some stopwords merge with each other or other words to form new words. Thus, it is impossible to find and remove most Amharic stopwords before the application of morphological analysis. This calls for a different consideration for Amharic stopword identification and removal in comparison with morphologically simpler languages such as English.

As we designed stem-based and root-based Amharic IR system, we also constructed stopword lists based on stem and root forms. In either of the cases, stopwords are identified after morphological segmentation of words from a large corpus of documents representing various domains and sources. For example, words such as /s

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually lalam t'at colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually w 'since he did not bring them'/ and /k t most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually l most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually l most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually k'ot such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually m 'even from big ones'/ undergo the following morphological process to extract attached stem-based stopwords.

_ _ _ _ _ _ _ k _t
/be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own s '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface rrows some punctuation marks such as '?' and '!' from Latin alphaic alphabet has numeral system, the Arabic numeral system is rather d by Amharic. ogy mplex morphology where many words could be generated through ivational processes from other word forms. Many surface forms of d from a base form through complex affixation, reduplication, and gitation. Amharic words can be marked for a number of functions. can be marked for a combination of person, case, gender, number, ood. An Amharic word might take up to four prefixes and five sufample, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ur prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ pro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / lar subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural r-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands er-ated from an Amharic root or its stems by changing the shape of or root, inserting vowels between root radicals, reduplicating one of stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are lates for verbal words. However, all variants have a single root ate. The major-ity of words in the language are generated from verbal ves, and ad-verbs can be derived from verbal roots. The derivation of ots usually l ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface orrows some punctuation marks such as '?' and '!' from Latin alphapic alphabet has numeral system, the Arabic numeral system is rather ed by Amharic. ology omplex morphology where many words could be generated through rivational processes from other word forms. Many surface forms of ed from a base form through complex affixation, reduplication, and igitation. Amharic words can be marked for a number of functions. b can be marked for a combination of person, case, gender, number, ood. An Amharic word might take up to four prefixes and five sufexample, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural er-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands ner-ated from an Amharic root or its stems by changing the shape of or root, inserting vowels between root radicals, reduplicating one of e stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are plates for verbal words. However, all variants have a single root late. The major-ity of words in the language are generated from verbal tives, and ad-verbs can be derived from verbal roots. The derivation of roots usually k'_ot ve base characters. The alphabet is conveniently written in a tabular format of columns. The first column represents the basic form with vowel ኧ /ə/ and the other ders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ d ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own uations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface ), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphalthough Ethiopic alphabet has numeral system, the Arabic numeral system is rather commonly used by Amharic.

mharic Morphology mharic has complex morphology where many words could be generated through tional and derivational processes from other word forms. Many surface forms of s can be formed from a base form through complex affixation, reduplication, and ic stem interdigitation. Amharic words can be marked for a number of functions. xample, a verb can be marked for a combination of person, case, gender, number, , aspect, and mood. An Amharic word might take up to four prefixes and five suf- [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is ructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first n singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object er for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of s can be gener-ated from an Amharic root or its stems by changing the shape of cters in a stem or root, inserting vowels between root radicals, reduplicating one of aracters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are ple stem templates for verbal words. However, all variants have a single root sentation template. The major-ity of words in the language are generated from verbal Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of s from verbal roots usually /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters wa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface also borrows some punctuation marks such as '?' and '!' from Latin alphah Ethiopic alphabet has numeral system, the Arabic numeral system is rather nly used by Amharic. Morphology c has complex morphology where many words could be generated through nd derivational processes from other word forms. Many surface forms of e formed from a base form through complex affixation, reduplication, and interdigitation. Amharic words can be marked for a number of functions. , a verb can be marked for a combination of person, case, gender, number, , and mood. An Amharic word might take up to four prefixes and five suf-For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / n singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural r for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands be gener-ated from an Amharic root or its stems by changing the shape of a stem or root, inserting vowels between root radicals, reduplicating one of s of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root n template. The major-ity of words in the language are generated from verbal , adjectives, and ad-verbs can be derived from verbal roots. The derivation of erbal roots usually _m i/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ions such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface c. It also borrows some punctuation marks such as '?' and '!' from Latin alphaugh Ethiopic alphabet has numeral system, the Arabic numeral system is rather monly used by Amharic. ric Morphology aric has complex morphology where many words could be generated through al and derivational processes from other word forms. Many surface forms of n be formed from a base form through complex affixation, reduplication, and tem interdigitation. Amharic words can be marked for a number of functions. ple, a verb can be marked for a combination of person, case, gender, number, ect, and mood. An Amharic word might take up to four prefixes and five suf-]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ /, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / rson singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural rker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands can be gener-ated from an Amharic root or its stems by changing the shape of in a stem or root, inserting vowels between root radicals, reduplicating one of cters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are stem templates for verbal words. However, all variants have a single root ation template. The major-ity of words in the language are generated from verbal uns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of m verbal roots usually s /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually l _ Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually l /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually _ Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually _m t' /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually _ Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually t spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually w /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually

[pre]-[stem]-[p]-[foc] [com]-[neg]-[cau]-[stem]-[3,p]
Similar to the stem-based stopword list, the root-based stopwords were built based on the root-based morphological process as shown in the following example.

_ --_ _ _ _ _ -_ k _t-l-k'_ot haric Language
mharic Writing System mharic is the working language of the government of Ethiopia currently having an ated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken ic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in pia, Amharic is the lingua franca and the most literary language serving as a meof instruction in the education system of the country for a long period. Amharic Ethiopic alphabet and has 34 base characters along with modifications on the reive base characters. The alphabet is conveniently written in a tabular format of columns. The first column represents the basic form with vowel ኧ /ə/ and the other ders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ d ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own uations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface ), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphalthough Ethiopic alphabet has numeral system, the Arabic numeral system is rather commonly used by Amharic.

mharic Morphology mharic has complex morphology where many words could be generated through tional and derivational processes from other word forms. Many surface forms of s can be formed from a base form through complex affixation, reduplication, and ic stem interdigitation. Amharic words can be marked for a number of functions. xample, a verb can be marked for a combination of person, case, gender, number, , aspect, and mood. An Amharic word might take up to four prefixes and five suf- [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is ructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first n singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object er for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of s can be gener-ated from an Amharic root or its stems by changing the shape of cters in a stem or root, inserting vowels between root radicals, reduplicating one of aracters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are ple stem templates for verbal words. However, all variants have a single root sentation template. The major-ity of words in the language are generated from verbal Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of s from verbal roots usually haric is the lingua franca and the most literary language serving as a meruction in the education system of the country for a long period. Amharic c alphabet and has 34 base characters along with modifications on the ree characters. The alphabet is conveniently written in a tabular format of ns. The first column represents the basic form with vowel ኧ /ə/ and the other present modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /. For example, the base character በ /bə/ has the following modifications: ቡ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters wa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface also borrows some punctuation marks such as '?' and '!' from Latin alphah Ethiopic alphabet has numeral system, the Arabic numeral system is rather nly used by Amharic. Morphology c has complex morphology where many words could be generated through nd derivational processes from other word forms. Many surface forms of e formed from a base form through complex affixation, reduplication, and interdigitation. Amharic words can be marked for a number of functions. , a verb can be marked for a combination of person, case, gender, number, , and mood. An Amharic word might take up to four prefixes and five suf-For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / n singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural r for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands be gener-ated from an Amharic root or its stems by changing the shape of a stem or root, inserting vowels between root radicals, reduplicating one of s of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root n template. The major-ity of words in the language are generated from verbal , adjectives, and ad-verbs can be derived from verbal roots. The derivation of erbal roots usually _m Amharic is the lingua franca and the most literary language serving as a meinstruction in the education system of the country for a long period. Amharic opic alphabet and has 34 base characters along with modifications on the rebase characters. The alphabet is conveniently written in a tabular format of umns. The first column represents the basic form with vowel ኧ /ə/ and the other represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ i/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ions such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface c. It also borrows some punctuation marks such as '?' and '!' from Latin alphaugh Ethiopic alphabet has numeral system, the Arabic numeral system is rather monly used by Amharic. ric Morphology aric has complex morphology where many words could be generated through al and derivational processes from other word forms. Many surface forms of n be formed from a base form through complex affixation, reduplication, and tem interdigitation. Amharic words can be marked for a number of functions. ple, a verb can be marked for a combination of person, case, gender, number, ect, and mood. An Amharic word might take up to four prefixes and five suf-]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ /, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / rson singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural rker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands can be gener-ated from an Amharic root or its stems by changing the shape of s in a stem or root, inserting vowels between root radicals, reduplicating one of cters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are stem templates for verbal words. However, all variants have a single root ation template. The major-ity of words in the language are generated from verbal uns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of m verbal roots usually s Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually l _ corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually l Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually _ corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually _m-t'_ corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually

t 2.
Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually w Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually

[pre[-[root]-[p]-[foc] [pre]-[neg]-[cau]-[root]-[p]
Statistical information about terms plays a significant role for identification of stopwords. However, the notion of term depends on the characteristics of languages. For morphologically simple languages such as English, stems can be considered as terms. However, this is not exactly the case with morphologically complex languages such as Amharic. We hypothesize that morphemes used to form Amharic words can be used as a basis for computing term statistics. Thus, in this work, we consider morphemes as terms. Both the stem-based and root-based stopwords were created based on the aggregation of the morpheme statistical information (frequency, mean, variance and entropy) from Amharic corpus. Accordingly, for the entire documents that we collected, we compute frequency, mean, variance and entropy of each morpheme in order to generate corpus-based Amharic stopword list as detailed below.

The frequency of morpheme is represented by document frequency and collection frequency. The document frequency of a morpheme is the number of documents where the morpheme occurs whereas the collection frequency is the total morpheme frequency throughout the corpus. In this work, we used un-normalized morpheme frequency. Morphemes were ranked according to their document frequency and collection frequency. Then, a threshold value was used to determine stopwords. Morphemes that are evenly distributed throughout the collection and satisfy the threshold value are considered as stopwords. The document frequency df of each morpheme is computed as:

d f (M i ) = N ∑ i=1 morpheme_ status(D i ) (1)
where M i is the ith morpheme in the corpus, D i is the ith document in the corpus, N is the total number of morphemes in the collection. If a morpheme appears in a given document, its status is 1 otherwise 0. The collection frequency cf of each morpheme is computed as:

c f (M i ) = N ∑ i=1 MFD i (2)
where MFD i is the morpheme frequency in each document, N is the total number of documents in the corpus.

The mean value of each morpheme is used to measure the overall distribution of morphemes in the whole corpus. The mean probability mp of each unique morpheme in all documents is computed as:

mp(M i ) = ∑ N i=1 p(M i ) N ( 3
)
where N is total number of documents and p(M i ) is morpheme probability which is computed as:

p(M i ) = MF TM (4)
where MF is morpheme frequency in each document and TM is the total number of morphemes in a document. The variance of morphemes is used to check the distribution of morphemes throughout the documents in the corpus. Variance v is computed as:

v(M i ) = ∑ n i=1 (n(Mi) -m(M i )) 2 N ( 5
)
where v(M i ) is the ith morpheme variance, N is the total number of distinct morphemes in the document, n(M i ) is normalized morpheme frequency in a document and m(M i ) is mean value computed as follows.

m(M i ) = ∑ n i=1 MF N ( 6
)
where MF is morpheme frequency and N is the number of words in a document.

Entropy is used to measure the information value e of each morpheme in the corpus. This method is based on the amount of information a morpheme carries. Stopwords are known to have low explanatory values. If the entropy value of a word is high, then the information value of the word is low. The entropy value of each morpheme in the corpus is calculated as:

e(M i ) = n ∑ i=1 p(M i ).log 1 p(M i ) (7)
where p(M i ) is the probability of morpheme frequency and is calculated by dividing the morpheme frequency with the total number of morphemes in the document. The stopwords were selected based on the aggregation of document frequency, mean, variance and entropy values of morphemes. Initially, four lists each containing the top 250 morphemes were selected using the statistical information of morphemes in the corpus. Out of these lists, 180 morphemes located across all the four lists were then selected through empirical analysis (see Table 4).

The final stopword list also includes few words which were selected manually based on Amharic subword class criteria. These words are functional words used mainly for the formation of phrases, sentences and paragraphs. These words are characterized by the lack of meaning by their own, inability to undergo morphological derivation and inflection, lack of morphemes for various parameters, and they have small word size [START_REF] Yimam | Yamarigna Sewasiw (Amharic Grammar)[END_REF] The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually nd 'like'/, /s limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually l 'about'/, / The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem limited in scope. The unavailability of full-fledged low-level Amharic NLP tools m difficult to create annotated corpus automatically. Moreover, there is lack of st reference collection making it a major impediment to the development of Amharic NLP tools. The objective of this research work is: (1) to promote publicly accessib haric resources including a standard test collection for IR, morphologically ann corpora and compiled stopwords list; and (2) to design Amharic IR system by gating the optimal representation of documents and queries considering both roo and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic la and its morphology. Section 3 discusses related work. In Section 4, we present t posed Amharic IR system architecture along with various options to represent A documents and queries. Section 5 presents the evaluation framework of the pr Amharic adhoc retrieval system including the presentation of the resources and c experimental setup, and experimental results. In Section 6, we present our con and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently hav estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are sp Ethiopia, Amharic is the lingua franca and the most literary language serving a dium of instruction in the education system of the country for a long period. A uses Ethiopic alphabet and has 34 base characters along with modifications on spective base characters. The alphabet is conveniently written in a tabular for seven columns. The first column represents the basic form with vowel ኧ /ə/ and th six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modificat /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized cha such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also i punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' ( colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated t inflectional and derivational processes from other word forms. Many surface fo words can be formed from a base form through complex affixation, reduplicatio Semitic stem interdigitation. Amharic words can be marked for a number of fun For example, a verb can be marked for a combination of person, case, gender, n tense, aspect, and mood. An Amharic word might take up to four prefixes and fi fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨn constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffix ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Tho of words can be gener-ated from an Amharic root or its stems by changing the sh characters in a stem or root, inserting vowels between root radicals, reduplicating the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. Th multiple stem templates for verbal words. However, all variants have a sing representation template. The major-ity of words in the language are generated from roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The deriva words from verbal roots usually sk 'up to'/, /w z t 'and so on'/, /go Appl. Sci. 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually 'bravo'/, /wa 'warning'/, /j The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re spective base characters. The alphabet is conveniently written in a tabular format o seven columns. The first column represents the basic form with vowel ኧ /ə/ and the othe six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized character such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rathe most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms o words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions For example, a verb can be marked for a combination of person, case, gender, number tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ i constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəs causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plura object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousand of words can be gener-ated from an Amharic root or its stems by changing the shape o characters in a stem or root, inserting vowels between root radicals, reduplicating one o the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single roo representation template. The major-ity of words in the language are generated from verba roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation o words from verbal roots usually l Appl. Sci. 2022, 12, x FOR PEER REVIEW 3 of limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes difficult to create annotated corpus automatically. Moreover, there is lack of standa reference collection making it a major impediment to the development of Amharic IR an NLP tools. The objective of this research work is: (1) to promote publicly accessible Am haric resources including a standard test collection for IR, morphologically annotate corpora and compiled stopwords list; and (2) to design Amharic IR system by inves gating the optimal representation of documents and queries considering both root-base and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic langua and its morphology. Section 3 discusses related work. In Section 4, we present the pr posed Amharic IR system architecture along with various options to represent Amhar documents and queries. Section 5 presents the evaluation framework of the propose Amharic adhoc retrieval system including the presentation of the resources and corpor experimental setup, and experimental results. In Section 6, we present our conclusio and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having a estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoke Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken Ethiopia, Amharic is the lingua franca and the most literary language serving as a m dium of instruction in the education system of the country for a long period. Amhar uses Ethiopic alphabet and has 34 base characters along with modifications on the r spective base characters. The alphabet is conveniently written in a tabular format seven columns. The first column represents the basic form with vowel ኧ /ə/ and the oth six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characte such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its ow punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (prefa colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alph bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rath most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated throug inflectional and derivational processes from other word forms. Many surface forms words can be formed from a base form through complex affixation, reduplication, an Semitic stem interdigitation. Amharic words can be marked for a number of function For example, a verb can be marked for a combination of person, case, gender, numbe tense, aspect, and mood. An Amharic word might take up to four prefixes and five su fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔə causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plur object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousan of words can be gener-ated from an Amharic root or its stems by changing the shape characters in a stem or root, inserting vowels between root radicals, reduplicating one the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There a multiple stem templates for verbal words. However, all variants have a single ro representation template. The major-ity of words in the language are generated from verb roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation words from verbal roots usually k 'instead'/, etc. Based on this criterion, we selected 42 words. Thus, the final stopword list contains 222 terms.

The stem-based and root-based stopwords are then removed from the respective documents and queries during the process of indexing and query processing. The stembased and root-based stopword lists we have built are re-usable, and they are one of the outputs of this research as we used a large set of documents from different domains and sources.

Indexing

For the purpose of IR, index terms are considered based on their frequency. Computing the frequency of Amharic terms is not a straightforward as there are several words derived from the same form. Root-based representation conflates all variants to a common root whereas stem-based representation does not guarantee this. The root-based representation can thus better compute the actual term frequency. The stem-based representation computes term frequency inaccurately for words derived from the same form. For example, variants of --/s-b-r/ are represented by more than one term for word-based and stem-based representations whereas a single term represents them in root-based representation (see Table 5 in which the frequency are based on the document presented in Appendix A). rganized as follows. Section 2 describes Amharic language discusses related work. In Section 4, we present the proitecture along with various options to represent Amharic on 5 presents the evaluation framework of the proposed including the presentation of the resources and corpora, rimental results. In Section 6, we present our conclusion ch directions. nguage of the government of Ethiopia currently having an 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in a franca and the most literary language serving as a mecation system of the country for a long period. Amharic s 34 base characters along with modifications on the realphabet is conveniently written in a tabular format of mn represents the basic form with vowel ኧ /ə/ and the ifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / or example, the base character በ /bə/ has the following ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The tuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), etc. It also borrows some punctuation marks such as '?' lthough Ethiopic alphabet has numeral system, the Arabic commonly used by Amharic. rphology where many words could be generated through rocesses from other word forms. Many surface forms of base form through complex affixation, reduplication, and mharic words can be marked for a number of functions. arked for a combination of person, case, gender, number, mharic word might take up to four prefixes and five sufrd ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed sition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-/ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular /, አቸው /ʔətʃəwɨ third person plural object marker for perand ና /na conjunction/). Thousands of words can be generits stems by changing the shape of characters in a stem or root radicals, reduplicating one of the characters of the stem ffixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for iants have a single root representation template. The majorre generated from verbal roots. Nouns, adjectives, and adal roots. The derivation of words from verbal roots usually u/ they 3 3 3 3 / rganized as follows. Section 2 describes Amharic language discusses related work. In Section 4, we present the proitecture along with various options to represent Amharic on 5 presents the evaluation framework of the proposed including the presentation of the resources and corpora, rimental results. In Section 6, we present our conclusion ch directions. nguage of the government of Ethiopia currently having an 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in a franca and the most literary language serving as a mecation system of the country for a long period. Amharic s 34 base characters along with modifications on the realphabet is conveniently written in a tabular format of mn represents the basic form with vowel ኧ /ə/ and the ifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / or example, the base character በ /bə/ has the following ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The tuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), etc. It also borrows some punctuation marks such as '?' lthough Ethiopic alphabet has numeral system, the Arabic commonly used by Amharic. rphology where many words could be generated through rocesses from other word forms. Many surface forms of base form through complex affixation, reduplication, and mharic words can be marked for a number of functions. arked for a combination of person, case, gender, number, mharic word might take up to four prefixes and five sufrd ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed sition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-/ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular /, አቸው /ʔətʃəwɨ third person plural object marker for perand ና /na conjunction/). Thousands of words can be generits stems by changing the shape of characters in a stem or root radicals, reduplicating one of the characters of the stem ffixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for iants have a single root representation template. The majorre generated from verbal roots. Nouns, adjectives, and adal roots. The derivation of words from verbal roots usually / he 4 4 5 17 /w abet and has 34 base characters along with modifications on the reacters. The alphabet is conveniently written in a tabular format of e first column represents the basic form with vowel ኧ /ə/ and the other t modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ example, the base character በ /bə/ has the following modifications: ቡ ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface orrows some punctuation marks such as '?' and '!' from Latin alphaopic alphabet has numeral system, the Arabic numeral system is rather ed by Amharic. ology omplex morphology where many words could be generated through rivational processes from other word forms. Many surface forms of ed from a base form through complex affixation, reduplication, and igitation. Amharic words can be marked for a number of functions. b can be marked for a combination of person, case, gender, number, mood. An Amharic word might take up to four prefixes and five sufexample, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ cipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural er-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands ner-ated from an Amharic root or its stems by changing the shape of or root, inserting vowels between root radicals, reduplicating one of e stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are plates for verbal words. However, all variants have a single root plate. The major-ity of words in the language are generated from verbal tives, and ad-verbs can be derived from verbal roots. The derivation of roots usually tion of documents and queries considering both root-based tations. rganized as follows. Section 2 describes Amharic language 3 discusses related work. In Section 4, we present the prohitecture along with various options to represent Amharic ion 5 presents the evaluation framework of the proposed m including the presentation of the resources and corpora, erimental results. In Section 6, we present our conclusion rch directions. anguage of the government of Ethiopia currently having an 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in ua franca and the most literary language serving as a meucation system of the country for a long period. Amharic as 34 base characters along with modifications on the realphabet is conveniently written in a tabular format of umn represents the basic form with vowel ኧ /ə/ and the difications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / For example, the base character በ /bə/ has the following ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The ctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), ), etc. It also borrows some punctuation marks such as '?'

lthough Ethiopic alphabet has numeral system, the Arabic t commonly used by Amharic. orphology where many words could be generated through processes from other word forms. Many surface forms of base form through complex affixation, reduplication, and Amharic words can be marked for a number of functions. arked for a combination of person, case, gender, number, Amharic word might take up to four prefixes and five suford ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed osition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-/ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular rb/, አቸው /ʔətʃəwɨ third person plural object marker for per-, and ና /na conjunction/). Thousands of words can be generits stems by changing the shape of characters in a stem or root radicals, reduplicating one of the characters of the stem affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for riants have a single root representation template. The majorare generated from verbal roots. Nouns, adjectives, and adbal roots. The derivation of words from verbal roots usually l habet and has 34 base characters along with modifications on the rearacters. The alphabet is conveniently written in a tabular format of he first column represents the basic form with vowel ኧ /ə/ and the other nt modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ r example, the base character በ /bə/ has the following modifications: ቡ /, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own h as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface borrows some punctuation marks such as '?' and '!' from Latin alphaiopic alphabet has numeral system, the Arabic numeral system is rather used by Amharic.

hology complex morphology where many words could be generated through derivational processes from other word forms. Many surface forms of med from a base form through complex affixation, reduplication, and rdigitation. Amharic words can be marked for a number of functions.

erb can be marked for a combination of person, case, gender, number, mood. An Amharic word might take up to four prefixes and five sufexample, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ecipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / gular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands gener-ated from an Amharic root or its stems by changing the shape of em or root, inserting vowels between root radicals, reduplicating one of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are mplates for verbal words. However, all variants have a single root plate. The major-ity of words in the language are generated from verbal ectives, and ad-verbs can be derived from verbal roots. The derivation of l roots usually / not 6 9 15 9 / ords list; and (2) to design Amharic IR system by investition of documents and queries considering both root-based tations. rganized as follows. Section 2 describes Amharic language 3 discusses related work. In Section 4, we present the prohitecture along with various options to represent Amharic ion 5 presents the evaluation framework of the proposed m including the presentation of the resources and corpora, erimental results. In Section 6, we present our conclusion rch directions. anguage of the government of Ethiopia currently having an 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in ua franca and the most literary language serving as a meucation system of the country for a long period. Amharic as 34 base characters along with modifications on the realphabet is conveniently written in a tabular format of umn represents the basic form with vowel ኧ /ə/ and the difications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / For example, the base character በ /bə/ has the following ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The ctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), ), etc. It also borrows some punctuation marks such as '?'

lthough Ethiopic alphabet has numeral system, the Arabic t commonly used by Amharic. orphology where many words could be generated through processes from other word forms. Many surface forms of base form through complex affixation, reduplication, and Amharic words can be marked for a number of functions. arked for a combination of person, case, gender, number, Amharic word might take up to four prefixes and five suford ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed osition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-/ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular rb/, አቸው /ʔətʃəwɨ third person plural object marker for per-, and ና /na conjunction/). Thousands of words can be generits stems by changing the shape of characters in a stem or root radicals, reduplicating one of the characters of the stem affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for riants have a single root representation template. The majorare generated from verbal roots. Nouns, adjectives, and adbal roots. The derivation of words from verbal roots usually ot

aric is the working language of the government of Ethiopia currently having an population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken nguage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Amharic is the lingua franca and the most literary language serving as a meinstruction in the education system of the country for a long period. Amharic opic alphabet and has 34 base characters along with modifications on the rebase characters. The alphabet is conveniently written in a tabular format of umns. The first column represents the basic form with vowel ኧ /ə/ and the other represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ i/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ions such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface c. It also borrows some punctuation marks such as '?' and '!' from Latin alphaugh Ethiopic alphabet has numeral system, the Arabic numeral system is rather monly used by Amharic.

ric Morphology aric has complex morphology where many words could be generated through al and derivational processes from other word forms. Many surface forms of n be formed from a base form through complex affixation, reduplication, and tem interdigitation. Amharic words can be marked for a number of functions. ple, a verb can be marked for a combination of person, case, gender, number, ect, and mood. An Amharic word might take up to four prefixes and five suf-. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is ed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, pro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first ngular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object or per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of n be gener-ated from an Amharic root or its stems by changing the shape of s in a stem or root, inserting vowels between root radicals, reduplicating one of cters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are stem templates for verbal words. However, all variants have a single root ation template. The major-ity of words in the language are generated from verbal uns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of m verbal roots usually tion in the education system of the country for a long period. Amharic lphabet and has 34 base characters along with modifications on the reharacters. The alphabet is conveniently written in a tabular format of The first column represents the basic form with vowel ኧ /ə/ and the other sent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ or example, the base character በ /bə/ has the following modifications: ቡ a/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters , ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ch as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface so borrows some punctuation marks such as '?' and '!' from Latin alphathiopic alphabet has numeral system, the Arabic numeral system is rather used by Amharic. tandard test collection for IR, morphologically annotated ords list; and (2) to design Amharic IR system by investition of documents and queries considering both root-based ations. rganized as follows. Section 2 describes Amharic language 3 discusses related work. In Section 4, we present the prohitecture along with various options to represent Amharic ion 5 presents the evaluation framework of the proposed m including the presentation of the resources and corpora, erimental results. In Section 6, we present our conclusion rch directions. anguage of the government of Ethiopia currently having an 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in ua franca and the most literary language serving as a meucation system of the country for a long period. Amharic as 34 base characters along with modifications on the realphabet is conveniently written in a tabular format of umn represents the basic form with vowel ኧ /ə/ and the difications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / For example, the base character በ /bə/ has the following ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The ctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), , etc. It also borrows some punctuation marks such as '?' lthough Ethiopic alphabet has numeral system, the Arabic t commonly used by Amharic. orphology where many words could be generated through processes from other word forms. Many surface forms of base form through complex affixation, reduplication, and Amharic words can be marked for a number of functions. arked for a combination of person, case, gender, number, Amharic word might take up to four prefixes and five sufrd ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed sition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-/ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular b/, አቸው /ʔətʃəwɨ third person plural object marker for per-, and ና /na conjunction/). Thousands of words can be generits stems by changing the shape of characters in a stem or root radicals, reduplicating one of the characters of the stem affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for riants have a single root representation template. The majorare generated from verbal roots. Nouns, adjectives, and adbal roots. The derivation of words from verbal roots usually is the lingua franca and the most literary language serving as a men in the education system of the country for a long period. Amharic abet and has 34 base characters along with modifications on the reacters. The alphabet is conveniently written in a tabular format of e first column represents the basic form with vowel ኧ /ə/ and the other t modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ example, the base character በ /bə/ has the following modifications: ቡ ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface orrows some punctuation marks such as '?' and '!' from Latin alphapic alphabet has numeral system, the Arabic numeral system is rather ed by Amharic. in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in c is the lingua franca and the most literary language serving as a meon in the education system of the country for a long period. Amharic habet and has 34 base characters along with modifications on the reracters. The alphabet is conveniently written in a tabular format of he first column represents the basic form with vowel ኧ /ə/ and the other nt modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ example, the base character በ /bə/ has the following modifications: ቡ , ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface borrows some punctuation marks such as '?' and '!' from Latin alphaiopic alphabet has numeral system, the Arabic numeral system is rather sed by Amharic. the working language of the government of Ethiopia currently having an lation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken e in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in ric is the lingua franca and the most literary language serving as a metion in the education system of the country for a long period. Amharic lphabet and has 34 base characters along with modifications on the reharacters. The alphabet is conveniently written in a tabular format of The first column represents the basic form with vowel ኧ /ə/ and the other sent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ or example, the base character በ /bə/ has the following modifications: ቡ a/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters , ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ch as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface o borrows some punctuation marks such as '?' and '!' from Latin alphathiopic alphabet has numeral system, the Arabic numeral system is rather used by Amharic. lability of full-fledged low-level Amharic NLP tools makes it corpus automatically. Moreover, there is lack of standard t a major impediment to the development of Amharic IR and his research work is: (1) to promote publicly accessible Amstandard test collection for IR, morphologically annotated ords list; and (2) to design Amharic IR system by investiation of documents and queries considering both root-based tations. organized as follows. Section 2 describes Amharic language 3 discusses related work. In Section 4, we present the prochitecture along with various options to represent Amharic tion 5 presents the evaluation framework of the proposed em including the presentation of the resources and corpora, erimental results. In Section 6, we present our conclusion arch directions. language of the government of Ethiopia currently having an r 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken ld after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in gua franca and the most literary language serving as a meducation system of the country for a long period. Amharic has 34 base characters along with modifications on the ree alphabet is conveniently written in a tabular format of lumn represents the basic form with vowel ኧ /ə/ and the odifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / . For example, the base character በ /bə/ has the following /, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are s ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The nctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), ), etc. It also borrows some punctuation marks such as '?' Although Ethiopic alphabet has numeral system, the Arabic st commonly used by Amharic. orphology where many words could be generated through l processes from other word forms. Many surface forms of a base form through complex affixation, reduplication, and . Amharic words can be marked for a number of functions. marked for a combination of person, case, gender, number, Amharic word might take up to four prefixes and five suford ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed osition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-ር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular erb/, አቸው /ʔətʃəwɨ third person plural object marker for per-/, and ና /na conjunction/). Thousands of words can be generr its stems by changing the shape of characters in a stem or n root radicals, reduplicating one of the characters of the stem g affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for ariants have a single root representation template. The majorare generated from verbal roots. Nouns, adjectives, and adrbal roots. The derivation of words from verbal roots usually age ng System e working language of the government of Ethiopia currently having an tion of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in c is the lingua franca and the most literary language serving as a meon in the education system of the country for a long period. Amharic habet and has 34 base characters along with modifications on the reracters. The alphabet is conveniently written in a tabular format of he first column represents the basic form with vowel ኧ /ə/ and the other nt modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ r example, the base character በ /bə/ has the following modifications: ቡ , ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own h as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface borrows some punctuation marks such as '?' and '!' from Latin alphaiopic alphabet has numeral system, the Arabic numeral system is rather sed by Amharic. the working language of the government of Ethiopia currently having an lation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken e in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in ric is the lingua franca and the most literary language serving as a metion in the education system of the country for a long period. Amharic lphabet and has 34 base characters along with modifications on the reharacters. The alphabet is conveniently written in a tabular format of The first column represents the basic form with vowel ኧ /ə/ and the other sent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ or example, the base character በ /bə/ has the following modifications: ቡ a/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters , ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ch as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface so borrows some punctuation marks such as '?' and '!' from Latin alphathiopic alphabet has numeral system, the Arabic numeral system is rather used by Amharic. is the working language of the government of Ethiopia currently having an pulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken age in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in haric is the lingua franca and the most literary language serving as a meuction in the education system of the country for a long period. Amharic alphabet and has 34 base characters along with modifications on the recharacters. The alphabet is conveniently written in a tabular format of s. The first column represents the basic form with vowel ኧ /ə/ and the other resent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ . For example, the base character በ /bə/ has the following modifications: ቡ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters a/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface also borrows some punctuation marks such as '?' and '!' from Latin alpha-Ethiopic alphabet has numeral system, the Arabic numeral system is rather ly used by Amharic. orphology has complex morphology where many words could be generated through nd derivational processes from other word forms. Many surface forms of formed from a base form through complex affixation, reduplication, and interdigitation. Amharic words can be marked for a number of functions. a verb can be marked for a combination of person, case, gender, number, and mood. An Amharic word might take up to four prefixes and five suf-For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is rom four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands be gener-ated from an Amharic root or its stems by changing the shape of a stem or root, inserting vowels between root radicals, reduplicating one of of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root template. The major-ity of words in the language are generated from verbal adjectives, and ad-verbs can be derived from verbal roots. The derivation of erbal roots usually b t of this paper is organized as follows. Section 2 describes Amharic language phology. Section 3 discusses related work. In Section 4, we present the proaric IR system architecture along with various options to represent Amharic and queries. Section 5 presents the evaluation framework of the proposed hoc retrieval system including the presentation of the resources and corpora, al setup, and experimental results. In Section 6, we present our conclusion ard further research directions. Language Writing System ic is the working language of the government of Ethiopia currently having an opulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken uage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in mharic is the lingua franca and the most literary language serving as a metruction in the education system of the country for a long period. Amharic ic alphabet and has 34 base characters along with modifications on the rese characters. The alphabet is conveniently written in a tabular format of ns. The first column represents the basic form with vowel ኧ /ə/ and the other present modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ o/. For example, the base character በ /bə/ has the following modifications: ቡ ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own s such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface It also borrows some punctuation marks such as '?' and '!' from Latin alphah Ethiopic alphabet has numeral system, the Arabic numeral system is rather only used by Amharic.

Morphology

ic has complex morphology where many words could be generated through and derivational processes from other word forms. Many surface forms of be formed from a base form through complex affixation, reduplication, and interdigitation. Amharic words can be marked for a number of functions.

e, a verb can be marked for a combination of person, case, gender, number, t, and mood. An Amharic word might take up to four prefixes and five suf-For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / on singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural er for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands n be gener-ated from an Amharic root or its stems by changing the shape of a stem or root, inserting vowels between root radicals, reduplicating one of rs of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are m templates for verbal words. However, all variants have a single root on template. The major-ity of words in the language are generated from verbal s, adjectives, and ad-verbs can be derived from verbal roots. The derivation of verbal roots usually rat rest of this paper is organized as follows. Section 2 describes Amharic language orphology. Section 3 discusses related work. In Section 4, we present the promharic IR system architecture along with various options to represent Amharic ts and queries. Section 5 presents the evaluation framework of the proposed adhoc retrieval system including the presentation of the resources and corpora, ental setup, and experimental results. In Section 6, we present our conclusion forward further research directions. ric Language aric Writing System haric is the working language of the government of Ethiopia currently having an d population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken anguage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in , Amharic is the lingua franca and the most literary language serving as a meinstruction in the education system of the country for a long period. Amharic iopic alphabet and has 34 base characters along with modifications on the rebase characters. The alphabet is conveniently written in a tabular format of lumns. The first column represents the basic form with vowel ኧ /ə/ and the other s represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ i/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own tions such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface tc. It also borrows some punctuation marks such as '?' and '!' from Latin alphaough Ethiopic alphabet has numeral system, the Arabic numeral system is rather monly used by Amharic.

aric Morphology haric has complex morphology where many words could be generated through al and derivational processes from other word forms. Many surface forms of n be formed from a base form through complex affixation, reduplication, and tem interdigitation. Amharic words can be marked for a number of functions.

ple, a verb can be marked for a combination of person, case, gender, number, pect, and mood. An Amharic word might take up to four prefixes and five suf-8]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ted from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ e/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / erson singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural arker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands can be gener-ated from an Amharic root or its stems by changing the shape of s in a stem or root, inserting vowels between root radicals, reduplicating one of cters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are stem templates for verbal words. However, all variants have a single root tation template. The major-ity of words in the language are generated from verbal uns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of om verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions.

For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually b corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions.

For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually r corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions.

For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually f this paper is organized as follows. Section 2 describes Amharic language ology. Section 3 discusses related work. In Section 4, we present the proic IR system architecture along with various options to represent Amharic d queries. Section 5 presents the evaluation framework of the proposed c retrieval system including the presentation of the resources and corpora, setup, and experimental results. In Section 6, we present our conclusion rd further research directions. nguage riting System is the working language of the government of Ethiopia currently having an ulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken age in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in aric is the lingua franca and the most literary language serving as a mection in the education system of the country for a long period. Amharic alphabet and has 34 base characters along with modifications on the recharacters. The alphabet is conveniently written in a tabular format of s. The first column represents the basic form with vowel ኧ /ə/ and the other resent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ For example, the base character በ /bə/ has the following modifications: ቡ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters a/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface also borrows some punctuation marks such as '?' and '!' from Latin alpha-Ethiopic alphabet has numeral system, the Arabic numeral system is rather ly used by Amharic. orphology has complex morphology where many words could be generated through d derivational processes from other word forms. Many surface forms of formed from a base form through complex affixation, reduplication, and interdigitation. Amharic words can be marked for a number of functions. a verb can be marked for a combination of person, case, gender, number, and mood. An Amharic word might take up to four prefixes and five sufor example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is rom four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands be gener-ated from an Amharic root or its stems by changing the shape of stem or root, inserting vowels between root radicals, reduplicating one of of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root template. The major-ity of words in the language are generated from verbal adjectives, and ad-verbs can be derived from verbal roots. The derivation of rbal roots usually b sed text representations. t of this paper is organized as follows. Section 2 describes Amharic language hology. Section 3 discusses related work. In Section 4, we present the proric IR system architecture along with various options to represent Amharic and queries. Section 5 presents the evaluation framework of the proposed oc retrieval system including the presentation of the resources and corpora, l setup, and experimental results. In Section 6, we present our conclusion ard further research directions. anguage Writing System c is the working language of the government of Ethiopia currently having an opulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken uage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in haric is the lingua franca and the most literary language serving as a meruction in the education system of the country for a long period. Amharic c alphabet and has 34 base characters along with modifications on the ree characters. The alphabet is conveniently written in a tabular format of ns. The first column represents the basic form with vowel ኧ /ə/ and the other present modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /. For example, the base character በ /bə/ has the following modifications: ቡ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters wa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own s such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface t also borrows some punctuation marks such as '?' and '!' from Latin alphah Ethiopic alphabet has numeral system, the Arabic numeral system is rather nly used by Amharic.

Morphology

c has complex morphology where many words could be generated through and derivational processes from other word forms. Many surface forms of e formed from a base form through complex affixation, reduplication, and interdigitation. Amharic words can be marked for a number of functions.

, a verb can be marked for a combination of person, case, gender, number, t, and mood. An Amharic word might take up to four prefixes and five suf-For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / n singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural r for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands be gener-ated from an Amharic root or its stems by changing the shape of a stem or root, inserting vowels between root radicals, reduplicating one of rs of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are m templates for verbal words. However, all variants have a single root n template. The major-ity of words in the language are generated from verbal , adjectives, and ad-verbs can be derived from verbal roots. The derivation of verbal roots usually ratot EVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually em-based text representations. he rest of this paper is organized as follows. Section 2 describes Amharic language s morphology. Section 3 discusses related work. In Section 4, we present the pro-Amharic IR system architecture along with various options to represent Amharic ents and queries. Section 5 presents the evaluation framework of the proposed ric adhoc retrieval system including the presentation of the resources and corpora, mental setup, and experimental results. In Section 6, we present our conclusion t forward further research directions. haric Language haric Writing System mharic is the working language of the government of Ethiopia currently having an ted population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken c language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in ia, Amharic is the lingua franca and the most literary language serving as a meof instruction in the education system of the country for a long period. Amharic thiopic alphabet and has 34 base characters along with modifications on the ree base characters. The alphabet is conveniently written in a tabular format of columns. The first column represents the basic form with vowel ኧ /ə/ and the other ers represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ d ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters s ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface , etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphalthough Ethiopic alphabet has numeral system, the Arabic numeral system is rather ommonly used by Amharic.

haric Morphology mharic has complex morphology where many words could be generated through ional and derivational processes from other word forms. Many surface forms of can be formed from a base form through complex affixation, reduplication, and c stem interdigitation. Amharic words can be marked for a number of functions. ample, a verb can be marked for a combination of person, case, gender, number, aspect, and mood. An Amharic word might take up to four prefixes and five suf- [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ucted from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ive/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / t person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands ds can be gener-ated from an Amharic root or its stems by changing the shape of ters in a stem or root, inserting vowels between root radicals, reduplicating one of aracters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are le stem templates for verbal words. However, all variants have a single root entation template. The major-ity of words in the language are generated from verbal Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of from verbal roots usually s the working language of the government of Ethiopia currently having an ulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken ge in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in aric is the lingua franca and the most literary language serving as a mection in the education system of the country for a long period. Amharic alphabet and has 34 base characters along with modifications on the recharacters. The alphabet is conveniently written in a tabular format of . The first column represents the basic form with vowel ኧ /ə/ and the other esent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ For example, the base character በ /bə/ has the following modifications: ቡ ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own uch as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface lso borrows some punctuation marks such as '?' and '!' from Latin alphathiopic alphabet has numeral system, the Arabic numeral system is rather y used by Amharic. orphology as complex morphology where many words could be generated through d derivational processes from other word forms. Many surface forms of formed from a base form through complex affixation, reduplication, and terdigitation. Amharic words can be marked for a number of functions. verb can be marked for a combination of person, case, gender, number, nd mood. An Amharic word might take up to four prefixes and five sufor example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is om four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands e gener-ated from an Amharic root or its stems by changing the shape of stem or root, inserting vowels between root radicals, reduplicating one of of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root of this paper is organized as follows. Section 2 describes Amharic language hology. Section 3 discusses related work. In Section 4, we present the proric IR system architecture along with various options to represent Amharic nd queries. Section 5 presents the evaluation framework of the proposed oc retrieval system including the presentation of the resources and corpora, setup, and experimental results. In Section 6, we present our conclusion ard further research directions. anguage riting System is the working language of the government of Ethiopia currently having an pulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken age in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in haric is the lingua franca and the most literary language serving as a meuction in the education system of the country for a long period. Amharic alphabet and has 34 base characters along with modifications on the recharacters. The alphabet is conveniently written in a tabular format of s. The first column represents the basic form with vowel ኧ /ə/ and the other resent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /. For example, the base character በ /bə/ has the following modifications: ቡ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters a/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface also borrows some punctuation marks such as '?' and '!' from Latin alpha-Ethiopic alphabet has numeral system, the Arabic numeral system is rather nly used by Amharic. orphology has complex morphology where many words could be generated through nd derivational processes from other word forms. Many surface forms of formed from a base form through complex affixation, reduplication, and interdigitation. Amharic words can be marked for a number of functions. a verb can be marked for a combination of person, case, gender, number, and mood. An Amharic word might take up to four prefixes and five suf-For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / n singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural r for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands be gener-ated from an Amharic root or its stems by changing the shape of a stem or root, inserting vowels between root radicals, reduplicating one of s of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root n template. The major-ity of words in the language are generated from verbal , adjectives, and ad-verbs can be derived from verbal roots. The derivation of erbal roots usually rat optimal representation of documents and queries considering both root-based based text representations.

est of this paper is organized as follows. Section 2 describes Amharic language orphology. Section 3 discusses related work. In Section 4, we present the proharic IR system architecture along with various options to represent Amharic s and queries. Section 5 presents the evaluation framework of the proposed dhoc retrieval system including the presentation of the resources and corpora, tal setup, and experimental results. In Section 6, we present our conclusion rward further research directions. c Language ic Writing System aric is the working language of the government of Ethiopia currently having an population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken nguage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Amharic is the lingua franca and the most literary language serving as a menstruction in the education system of the country for a long period. Amharic pic alphabet and has 34 base characters along with modifications on the rease characters. The alphabet is conveniently written in a tabular format of mns. The first column represents the basic form with vowel ኧ /ə/ and the other represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ons such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface . It also borrows some punctuation marks such as '?' and '!' from Latin alphaugh Ethiopic alphabet has numeral system, the Arabic numeral system is rather monly used by Amharic.

ic Morphology aric has complex morphology where many words could be generated through l and derivational processes from other word forms. Many surface forms of be formed from a base form through complex affixation, reduplication, and em interdigitation. Amharic words can be marked for a number of functions. le, a verb can be marked for a combination of person, case, gender, number, ect, and mood. An Amharic word might take up to four prefixes and five suf-]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is d from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ , ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / rson singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural rker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands can be gener-ated from an Amharic root or its stems by changing the shape of in a stem or root, inserting vowels between root radicals, reduplicating one of ters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are stem templates for verbal words. However, all variants have a single root tion template. The major-ity of words in the language are generated from verbal ns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of m verbal roots usually n he optimal representation of documents and queries considering both root-based -based text representations. rest of this paper is organized as follows. Section 2 describes Amharic language morphology. Section 3 discusses related work. In Section 4, we present the promharic IR system architecture along with various options to represent Amharic nts and queries. Section 5 presents the evaluation framework of the proposed c adhoc retrieval system including the presentation of the resources and corpora, ental setup, and experimental results. In Section 6, we present our conclusion forward further research directions. ric Language aric Writing System haric is the working language of the government of Ethiopia currently having an d population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in , Amharic is the lingua franca and the most literary language serving as a meinstruction in the education system of the country for a long period. Amharic iopic alphabet and has 34 base characters along with modifications on the rebase characters. The alphabet is conveniently written in a tabular format of lumns. The first column represents the basic form with vowel ኧ /ə/ and the other rs represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own tions such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface tc. It also borrows some punctuation marks such as '?' and '!' from Latin alphaough Ethiopic alphabet has numeral system, the Arabic numeral system is rather mmonly used by Amharic.

aric Morphology haric has complex morphology where many words could be generated through nal and derivational processes from other word forms. Many surface forms of an be formed from a base form through complex affixation, reduplication, and stem interdigitation. Amharic words can be marked for a number of functions. ple, a verb can be marked for a combination of person, case, gender, number, pect, and mood. An Amharic word might take up to four prefixes and five suf-8]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ted from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ e/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / erson singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural arker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands s can be gener-ated from an Amharic root or its stems by changing the shape of rs in a stem or root, inserting vowels between root radicals, reduplicating one of acters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are stem templates for verbal words. However, all variants have a single root tation template. The major-ity of words in the language are generated from verbal ouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of om verbal roots usually s the working language of the government of Ethiopia currently having an ulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken ge in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in aric is the lingua franca and the most literary language serving as a mection in the education system of the country for a long period. Amharic alphabet and has 34 base characters along with modifications on the recharacters. The alphabet is conveniently written in a tabular format of . The first column represents the basic form with vowel ኧ /ə/ and the other esent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ For example, the base character በ /bə/ has the following modifications: ቡ ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own uch as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface lso borrows some punctuation marks such as '?' and '!' from Latin alphathiopic alphabet has numeral system, the Arabic numeral system is rather y used by Amharic. orphology as complex morphology where many words could be generated through d derivational processes from other word forms. Many surface forms of formed from a base form through complex affixation, reduplication, and terdigitation. Amharic words can be marked for a number of functions. verb can be marked for a combination of person, case, gender, number, nd mood. An Amharic word might take up to four prefixes and five sufor example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is om four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands e gener-ated from an Amharic root or its stems by changing the shape of stem or root, inserting vowels between root radicals, reduplicating one of of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root of this paper is organized as follows. Section 2 describes Amharic language hology. Section 3 discusses related work. In Section 4, we present the proric IR system architecture along with various options to represent Amharic nd queries. Section 5 presents the evaluation framework of the proposed oc retrieval system including the presentation of the resources and corpora, setup, and experimental results. In Section 6, we present our conclusion ard further research directions. anguage riting System is the working language of the government of Ethiopia currently having an pulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken age in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in haric is the lingua franca and the most literary language serving as a meruction in the education system of the country for a long period. Amharic alphabet and has 34 base characters along with modifications on the recharacters. The alphabet is conveniently written in a tabular format of s. The first column represents the basic form with vowel ኧ /ə/ and the other resent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /. For example, the base character በ /bə/ has the following modifications: ቡ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters a/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface also borrows some punctuation marks such as '?' and '!' from Latin alpha-Ethiopic alphabet has numeral system, the Arabic numeral system is rather nly used by Amharic. orphology has complex morphology where many words could be generated through nd derivational processes from other word forms. Many surface forms of formed from a base form through complex affixation, reduplication, and interdigitation. Amharic words can be marked for a number of functions. a verb can be marked for a combination of person, case, gender, number, , and mood. An Amharic word might take up to four prefixes and five suf-For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / n singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural r for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands be gener-ated from an Amharic root or its stems by changing the shape of a stem or root, inserting vowels between root radicals, reduplicating one of s of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are est of this paper is organized as follows. Section 2 describes Amharic language orphology. Section 3 discusses related work. In Section 4, we present the proharic IR system architecture along with various options to represent Amharic s and queries. Section 5 presents the evaluation framework of the proposed dhoc retrieval system including the presentation of the resources and corpora, tal setup, and experimental results. In Section 6, we present our conclusion rward further research directions. c Language ic Writing System aric is the working language of the government of Ethiopia currently having an population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken nguage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Amharic is the lingua franca and the most literary language serving as a menstruction in the education system of the country for a long period. Amharic pic alphabet and has 34 base characters along with modifications on the rease characters. The alphabet is conveniently written in a tabular format of mns. The first column represents the basic form with vowel ኧ /ə/ and the other represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ons such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface . It also borrows some punctuation marks such as '?' and '!' from Latin alphaugh Ethiopic alphabet has numeral system, the Arabic numeral system is rather monly used by Amharic.

ic Morphology aric has complex morphology where many words could be generated through l and derivational processes from other word forms. Many surface forms of be formed from a base form through complex affixation, reduplication, and em interdigitation. Amharic words can be marked for a number of functions. ple, a verb can be marked for a combination of person, case, gender, number, ect, and mood. An Amharic word might take up to four prefixes and five suf-]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is d from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ , ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / rson singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural rker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands can be gener-ated from an Amharic root or its stems by changing the shape of in a stem or root, inserting vowels between root radicals, reduplicating one of ters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are stem templates for verbal words. However, all variants have a single root tion template. The major-ity of words in the language are generated from verbal ns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of m verbal roots usually this paper is organized as follows. Section 2 describes Amharic language logy. Section 3 discusses related work. In Section 4, we present the pro-IR system architecture along with various options to represent Amharic queries. Section 5 presents the evaluation framework of the proposed etrieval system including the presentation of the resources and corpora, tup, and experimental results. In Section 6, we present our conclusion further research directions. guage iting System the working language of the government of Ethiopia currently having an lation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken e in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in ric is the lingua franca and the most literary language serving as a metion in the education system of the country for a long period. Amharic lphabet and has 34 base characters along with modifications on the reharacters. The alphabet is conveniently written in a tabular format of The first column represents the basic form with vowel ኧ /ə/ and the other sent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ or example, the base character በ /bə/ has the following modifications: ቡ a/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters , ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ch as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface so borrows some punctuation marks such as '?' and '!' from Latin alphathiopic alphabet has numeral system, the Arabic numeral system is rather used by Amharic. rphology as complex morphology where many words could be generated through derivational processes from other word forms. Many surface forms of rmed from a base form through complex affixation, reduplication, and terdigitation. Amharic words can be marked for a number of functions. verb can be marked for a combination of person, case, gender, number, d mood. An Amharic word might take up to four prefixes and five sufr example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is m four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ingular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural r per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands gener-ated from an Amharic root or its stems by changing the shape of tem or root, inserting vowels between root radicals, reduplicating one of f the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root is the working language of the government of Ethiopia currently having an ulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken ge in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in aric is the lingua franca and the most literary language serving as a mection in the education system of the country for a long period. Amharic alphabet and has 34 base characters along with modifications on the recharacters. The alphabet is conveniently written in a tabular format of s. The first column represents the basic form with vowel ኧ /ə/ and the other esent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ For example, the base character በ /bə/ has the following modifications: ቡ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters a/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface lso borrows some punctuation marks such as '?' and '!' from Latin alpha-Ethiopic alphabet has numeral system, the Arabic numeral system is rather ly used by Amharic. orphology has complex morphology where many words could be generated through d derivational processes from other word forms. Many surface forms of formed from a base form through complex affixation, reduplication, and nterdigitation. Amharic words can be marked for a number of functions. a verb can be marked for a combination of person, case, gender, number, and mood. An Amharic word might take up to four prefixes and five sufor example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is om four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands be gener-ated from an Amharic root or its stems by changing the shape of stem or root, inserting vowels between root radicals, reduplicating one of of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root st of this paper is organized as follows. Section 2 describes Amharic language rphology. Section 3 discusses related work. In Section 4, we present the proaric IR system architecture along with various options to represent Amharic and queries. Section 5 presents the evaluation framework of the proposed hoc retrieval system including the presentation of the resources and corpora, tal setup, and experimental results. In Section 6, we present our conclusion ward further research directions. Language c Writing System ric is the working language of the government of Ethiopia currently having an population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken guage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in mharic is the lingua franca and the most literary language serving as a mestruction in the education system of the country for a long period. Amharic ic alphabet and has 34 base characters along with modifications on the rese characters. The alphabet is conveniently written in a tabular format of mns. The first column represents the basic form with vowel ኧ /ə/ and the other epresent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ns such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface It also borrows some punctuation marks such as '?' and '!' from Latin alphagh Ethiopic alphabet has numeral system, the Arabic numeral system is rather only used by Amharic.

c Morphology ric has complex morphology where many words could be generated through and derivational processes from other word forms. Many surface forms of be formed from a base form through complex affixation, reduplication, and m interdigitation. Amharic words can be marked for a number of functions. le, a verb can be marked for a combination of person, case, gender, number, ct, and mood. An Amharic word might take up to four prefixes and five suf-For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / son singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural ker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands an be gener-ated from an Amharic root or its stems by changing the shape of in a stem or root, inserting vowels between root radicals, reduplicating one of ers of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are em templates for verbal words. However, all variants have a single root ion template. The major-ity of words in the language are generated from verbal s, adjectives, and ad-verbs can be derived from verbal roots. The derivation of verbal roots usually this paper is organized as follows. Section 2 describes Amharic language logy. Section 3 discusses related work. In Section 4, we present the pro-IR system architecture along with various options to represent Amharic queries. Section 5 presents the evaluation framework of the proposed etrieval system including the presentation of the resources and corpora, tup, and experimental results. In Section 6, we present our conclusion further research directions. guage iting System the working language of the government of Ethiopia currently having an lation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken e in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in ric is the lingua franca and the most literary language serving as a metion in the education system of the country for a long period. Amharic lphabet and has 34 base characters along with modifications on the reharacters. The alphabet is conveniently written in a tabular format of The first column represents the basic form with vowel ኧ /ə/ and the other sent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ or example, the base character በ /bə/ has the following modifications: ቡ a/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters , ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ch as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface so borrows some punctuation marks such as '?' and '!' from Latin alphathiopic alphabet has numeral system, the Arabic numeral system is rather used by Amharic. rphology as complex morphology where many words could be generated through derivational processes from other word forms. Many surface forms of rmed from a base form through complex affixation, reduplication, and terdigitation. Amharic words can be marked for a number of functions. verb can be marked for a combination of person, case, gender, number, d mood. An Amharic word might take up to four prefixes and five sufr example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is m four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ingular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural r per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands gener-ated from an Amharic root or its stems by changing the shape of tem or root, inserting vowels between root radicals, reduplicating one of f the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root is the working language of the government of Ethiopia currently having an ulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken ge in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in aric is the lingua franca and the most literary language serving as a mection in the education system of the country for a long period. Amharic alphabet and has 34 base characters along with modifications on the recharacters. The alphabet is conveniently written in a tabular format of s. The first column represents the basic form with vowel ኧ /ə/ and the other esent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ For example, the base character በ /bə/ has the following modifications: ቡ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters a/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface lso borrows some punctuation marks such as '?' and '!' from Latin alpha-Ethiopic alphabet has numeral system, the Arabic numeral system is rather ly used by Amharic. orphology has complex morphology where many words could be generated through d derivational processes from other word forms. Many surface forms of formed from a base form through complex affixation, reduplication, and nterdigitation. Amharic words can be marked for a number of functions. a verb can be marked for a combination of person, case, gender, number, and mood. An Amharic word might take up to four prefixes and five sufor example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is om four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands be gener-ated from an Amharic root or its stems by changing the shape of stem or root, inserting vowels between root radicals, reduplicating one of of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root template. The major-ity of words in the language are generated from verbal adjectives, and ad-verbs can be derived from verbal roots. The derivation of rbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language nd its morphology. Section 3 discusses related work. In Section 4, we present the proosed Amharic IR system architecture along with various options to represent Amharic ocuments and queries. Section 5 presents the evaluation framework of the proposed mharic adhoc retrieval system including the presentation of the resources and corpora, xperimental setup, and experimental results. In Section 6, we present our conclusion nd put forward further research directions. . Amharic Language .1. Amharic Writing System Amharic is the working language of the government of Ethiopia currently having an stimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken emitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in thiopia, Amharic is the lingua franca and the most literary language serving as a meium of instruction in the education system of the country for a long period. Amharic ses Ethiopic alphabet and has 34 base characters along with modifications on the reective base characters. The alphabet is conveniently written in a tabular format of ven columns. The first column represents the basic form with vowel ኧ /ə/ and the other x orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ u/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters ch as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own unctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface lon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphaet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather ost commonly used by Amharic.

.2. Amharic Morphology

Amharic has complex morphology where many words could be generated through flectional and derivational processes from other word forms. Many surface forms of ords can be formed from a base form through complex affixation, reduplication, and emitic stem interdigitation. Amharic words can be marked for a number of functions.

or example, a verb can be marked for a combination of person, case, gender, number, nse, aspect, and mood. An Amharic word might take up to four prefixes and five sufxes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is nstructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ usative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural bject marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands f words can be gener-ated from an Amharic root or its stems by changing the shape of aracters in a stem or root, inserting vowels between root radicals, reduplicating one of e characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are ultiple stem templates for verbal words. However, all variants have a single root presentation template. The major-ity of words in the language are generated from verbal ots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of ords from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions.

For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal rest of this paper is organized as follows. Section 2 describes Amharic language orphology. Section 3 discusses related work. In Section 4, we present the proharic IR system architecture along with various options to represent Amharic ts and queries. Section 5 presents the evaluation framework of the proposed adhoc retrieval system including the presentation of the resources and corpora, ntal setup, and experimental results. In Section 6, we present our conclusion orward further research directions. ic Language ric Writing System aric is the working language of the government of Ethiopia currently having an population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken nguage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Amharic is the lingua franca and the most literary language serving as a meinstruction in the education system of the country for a long period. Amharic opic alphabet and has 34 base characters along with modifications on the rebase characters. The alphabet is conveniently written in a tabular format of umns. The first column represents the basic form with vowel ኧ /ə/ and the other s represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ i/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ions such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface c. It also borrows some punctuation marks such as '?' and '!' from Latin alphaugh Ethiopic alphabet has numeral system, the Arabic numeral system is rather monly used by Amharic.

ric Morphology aric has complex morphology where many words could be generated through al and derivational processes from other word forms. Many surface forms of n be formed from a base form through complex affixation, reduplication, and tem interdigitation. Amharic words can be marked for a number of functions. ple, a verb can be marked for a combination of person, case, gender, number, ect, and mood. An Amharic word might take up to four prefixes and five suf-]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ /, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / erson singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural rker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands can be gener-ated from an Amharic root or its stems by changing the shape of s in a stem or root, inserting vowels between root radicals, reduplicating one of cters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are stem templates for verbal words. However, all variants have a single root ation template. The major-ity of words in the language are generated from verbal uns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of m verbal roots usually n in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it t to create annotated corpus automatically. Moreover, there is lack of standard ce collection making it a major impediment to the development of Amharic IR and ols. The objective of this research work is: (1) to promote publicly accessible Amsources including a standard test collection for IR, morphologically annotated and compiled stopwords list; and (2) to design Amharic IR system by investithe optimal representation of documents and queries considering both root-based m-based text representations. e rest of this paper is organized as follows. Section 2 describes Amharic language morphology. Section 3 discusses related work. In Section 4, we present the promharic IR system architecture along with various options to represent Amharic ents and queries. Section 5 presents the evaluation framework of the proposed ic adhoc retrieval system including the presentation of the resources and corpora, ental setup, and experimental results. In Section 6, we present our conclusion t forward further research directions. aric Language haric Writing System haric is the working language of the government of Ethiopia currently having an ed population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in a, Amharic is the lingua franca and the most literary language serving as a mef instruction in the education system of the country for a long period. Amharic hiopic alphabet and has 34 base characters along with modifications on the ree base characters. The alphabet is conveniently written in a tabular format of olumns. The first column represents the basic form with vowel ኧ /ə/ and the other ers represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphahough Ethiopic alphabet has numeral system, the Arabic numeral system is rather mmonly used by Amharic.

haric Morphology haric has complex morphology where many words could be generated through onal and derivational processes from other word forms. Many surface forms of can be formed from a base form through complex affixation, reduplication, and stem interdigitation. Amharic words can be marked for a number of functions. mple, a verb can be marked for a combination of person, case, gender, number, spect, and mood. An Amharic word might take up to four prefixes and five suf-18]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is cted from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ve/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural arker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands s can be gener-ated from an Amharic root or its stems by changing the shape of ers in a stem or root, inserting vowels between root radicals, reduplicating one of racters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are e stem templates for verbal words. However, all variants have a single root ntation template. The major-ity of words in the language are generated from verbal ouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of rom verbal roots usually rest of this paper is organized as follows. Section 2 describes Amharic language orphology. Section 3 discusses related work. In Section 4, we present the proharic IR system architecture along with various options to represent Amharic ts and queries. Section 5 presents the evaluation framework of the proposed adhoc retrieval system including the presentation of the resources and corpora, ntal setup, and experimental results. In Section 6, we present our conclusion orward further research directions. ic Language ric Writing System aric is the working language of the government of Ethiopia currently having an population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken nguage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Amharic is the lingua franca and the most literary language serving as a meinstruction in the education system of the country for a long period. Amharic opic alphabet and has 34 base characters along with modifications on the rebase characters. The alphabet is conveniently written in a tabular format of umns. The first column represents the basic form with vowel ኧ /ə/ and the other s represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ i/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ions such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface c. It also borrows some punctuation marks such as '?' and '!' from Latin alphaugh Ethiopic alphabet has numeral system, the Arabic numeral system is rather monly used by Amharic.

ric Morphology aric has complex morphology where many words could be generated through al and derivational processes from other word forms. Many surface forms of n be formed from a base form through complex affixation, reduplication, and tem interdigitation. Amharic words can be marked for a number of functions. ple, a verb can be marked for a combination of person, case, gender, number, ect, and mood. An Amharic word might take up to four prefixes and five suf-]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ /, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / erson singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural rker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands can be gener-ated from an Amharic root or its stems by changing the shape of s in a stem or root, inserting vowels between root radicals, reduplicating one of cters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are stem templates for verbal words. However, all variants have a single root ation template. The major-ity of words in the language are generated from verbal uns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of m verbal roots usually est of this paper is organized as follows. Section 2 describes Amharic language rphology. Section 3 discusses related work. In Section 4, we present the proharic IR system architecture along with various options to represent Amharic s and queries. Section 5 presents the evaluation framework of the proposed dhoc retrieval system including the presentation of the resources and corpora, tal setup, and experimental results. In Section 6, we present our conclusion rward further research directions. c Language ic Writing System aric is the working language of the government of Ethiopia currently having an population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken guage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Amharic is the lingua franca and the most literary language serving as a mestruction in the education system of the country for a long period. Amharic pic alphabet and has 34 base characters along with modifications on the rease characters. The alphabet is conveniently written in a tabular format of mns. The first column represents the basic form with vowel ኧ /ə/ and the other represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ns such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface . It also borrows some punctuation marks such as '?' and '!' from Latin alphaugh Ethiopic alphabet has numeral system, the Arabic numeral system is rather monly used by Amharic.

ic Morphology aric has complex morphology where many words could be generated through l and derivational processes from other word forms. Many surface forms of be formed from a base form through complex affixation, reduplication, and em interdigitation. Amharic words can be marked for a number of functions. le, a verb can be marked for a combination of person, case, gender, number, ect, and mood. An Amharic word might take up to four prefixes and five suf-. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is d from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ , ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / rson singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural rker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands can be gener-ated from an Amharic root or its stems by changing the shape of in a stem or root, inserting vowels between root radicals, reduplicating one of ters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are tem templates for verbal words. However, all variants have a single root tion template. The major-ity of words in the language are generated from verbal ns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of verbal roots usually e rest of this paper is organized as follows. Section 2 describes Amharic language morphology. Section 3 discusses related work. In Section 4, we present the promharic IR system architecture along with various options to represent Amharic ents and queries. Section 5 presents the evaluation framework of the proposed ic adhoc retrieval system including the presentation of the resources and corpora, ental setup, and experimental results. In Section 6, we present our conclusion t forward further research directions. aric Language haric Writing System haric is the working language of the government of Ethiopia currently having an ed population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in a, Amharic is the lingua franca and the most literary language serving as a mef instruction in the education system of the country for a long period. Amharic hiopic alphabet and has 34 base characters along with modifications on the ree base characters. The alphabet is conveniently written in a tabular format of olumns. The first column represents the basic form with vowel ኧ /ə/ and the other ers represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphahough Ethiopic alphabet has numeral system, the Arabic numeral system is rather mmonly used by Amharic.

haric Morphology haric has complex morphology where many words could be generated through onal and derivational processes from other word forms. Many surface forms of can be formed from a base form through complex affixation, reduplication, and stem interdigitation. Amharic words can be marked for a number of functions. mple, a verb can be marked for a combination of person, case, gender, number, spect, and mood. An Amharic word might take up to four prefixes and five suf-18]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is cted from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ve/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural arker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands s can be gener-ated from an Amharic root or its stems by changing the shape of ers in a stem or root, inserting vowels between root radicals, reduplicating one of racters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are e stem templates for verbal words. However, all variants have a single root ntation template. The major-ity of words in the language are generated from verbal ouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions.

For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions.

For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually /) Generally, the term frequency for root-based representation is higher than or equal to the stem-based one; so will be the associated with if computed with the usual formula (See Equation ( 8)).

w(t, d) = t f .log N d f (8)
where w(t,d) is weight of a term t in a document d, tf is term frequency, N is total number of documents in a corpus, and df is document frequency. On the other hand, the number of stem-based terms is larger than or equal to the number of root-based terms in Amharic documents. For example, in the document presented in Appendix A, there are 405 words, 213 stems and 168 roots. The effect of morphological analysis on Amharic IR using stembased and root-based indexes is evaluated in Section 5.

Word Embedding

Similar to other languages, in Amharic language semantically related words co-occur many times in a text document. User information need might be incomplete or contain all co-occurrence words. As a result of this, relevant documents could not be retrieved. Therefore, user information need should be completed by query expansion in order to retrieve more relevant documents. To overcome the problem of vocabulary mismatch between index term and query term, we used word embedding vector representation for each word in the vocabulary. Each query terms are expanded by semantically and syntactically related terms using word2vec developed by Mikolov et al. [START_REF] Mikolov | Distributed representations of words and phrases and their compositionality[END_REF]. To verify the impact of query expansion on Amharic IR using word embedding algorithms, we created CBOW and Skip-gram models on stem-based and root-based corpora. CBOW and skip-gram models capture order relationships between words and they are effective for NLP tasks involving the use of word similarity and word analogy. We used them to capture semantic relations between words in queries and relevant documents. Four neural network models: stem-based with CBOW, stem-based with Skip-gram, root-based with CBOW and root-based with Skip-gram models are created offline and used for expanding stembased and root-based query terms using stem-based and root-based corpora, respectively. The original query terms are matched with vocabulary words in the models to find their vector values. Then, the similarity between the features of each original query word and vocabulary words is computed to identify similar terms for each query term. The similarity sim between a query term q and a corpus word d is computed using cosine similarity as shown in Equation [START_REF] Smeaton | Progress in the application of natural language processing to information retrieval tasks[END_REF].

sim(q, d) = ∑ i qi.di ∑ i qi 2 ∑ i di 2 (9)
where qi is vector representation of the ith query term and di is the vector representation of the ith word in the corpus. The top 5 most related terms are used to expand query terms. Nearest neighbors or syntactically related words are used to expand query. Words that are used in similar contexts with respect to a given word frequently are used as expanded terms.

Matching and Ranking

In the proposed system, the extraction of index and query terms from documents and user queries uses the same workflow with text preprocessing, morphological analysis and stopword removal. Searching for relevant documents is based on matching query terms (representing information need of users) with index terms (representing documents). We used exact vocabulary term matching which searches documents that contain the query terms without analyzing the semantics of words and without considering the semantic connections between them. The retrieval probability of a relevant document for a given query is different in case of stem-based and root-based retrievals. In general, the retrieval probability of a relevant document for a given query in case of root-based matching is higher than stem-based matching. For example, consider the sample document (Appendix A) and the following four query terms derived from --/s-b-r/: 1.

/s

3 of 29 cope. The unavailability of full-fledged low-level Amharic NLP tools makes it create annotated corpus automatically. Moreover, there is lack of standard llection making it a major impediment to the development of Amharic IR and The objective of this research work is: (1) to promote publicly accessible Amrces including a standard test collection for IR, morphologically annotated compiled stopwords list; and (2) to design Amharic IR system by investiptimal representation of documents and queries considering both root-based ased text representations. st of this paper is organized as follows. Section 2 describes Amharic language phology. Section 3 discusses related work. In Section 4, we present the proaric IR system architecture along with various options to represent Amharic and queries. Section 5 presents the evaluation framework of the proposed hoc retrieval system including the presentation of the resources and corpora, al setup, and experimental results. In Section 6, we present our conclusion ward further research directions.

Language

Writing System ic is the working language of the government of Ethiopia currently having an opulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken uage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in mharic is the lingua franca and the most literary language serving as a metruction in the education system of the country for a long period. Amharic ic alphabet and has 34 base characters along with modifications on the rese characters. The alphabet is conveniently written in a tabular format of ns. The first column represents the basic form with vowel ኧ /ə/ and the other epresent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ o/. For example, the base character በ /bə/ has the following modifications: ቡ ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own s such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface It also borrows some punctuation marks such as '?' and '!' from Latin alphagh Ethiopic alphabet has numeral system, the Arabic numeral system is rather only used by Amharic.

Morphology

ic has complex morphology where many words could be generated through and derivational processes from other word forms. Many surface forms of be formed from a base form through complex affixation, reduplication, and interdigitation. Amharic words can be marked for a number of functions. e, a verb can be marked for a combination of person, case, gender, number, t, and mood. An Amharic word might take up to four prefixes and five suf-For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / on singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural er for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands n be gener-ated from an Amharic root or its stems by changing the shape of n a stem or root, inserting vowels between root radicals, reduplicating one of rs of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are em templates for verbal words. However, all variants have a single root on template. The major-ity of words in the language are generated from verbal s, adjectives, and ad-verbs can be derived from verbal roots. The derivation of verbal roots usually b 3 of 29 scope. The unavailability of full-fledged low-level Amharic NLP tools makes it o create annotated corpus automatically. Moreover, there is lack of standard collection making it a major impediment to the development of Amharic IR and . The objective of this research work is: (1) to promote publicly accessible Amurces including a standard test collection for IR, morphologically annotated nd compiled stopwords list; and (2) to design Amharic IR system by investioptimal representation of documents and queries considering both root-based based text representations. est of this paper is organized as follows. Section 2 describes Amharic language orphology. Section 3 discusses related work. In Section 4, we present the proharic IR system architecture along with various options to represent Amharic ts and queries. Section 5 presents the evaluation framework of the proposed adhoc retrieval system including the presentation of the resources and corpora, ntal setup, and experimental results. In Section 6, we present our conclusion rward further research directions. ic Language ric Writing System aric is the working language of the government of Ethiopia currently having an population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken nguage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Amharic is the lingua franca and the most literary language serving as a menstruction in the education system of the country for a long period. Amharic opic alphabet and has 34 base characters along with modifications on the rease characters. The alphabet is conveniently written in a tabular format of mns. The first column represents the basic form with vowel ኧ /ə/ and the other represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ons such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface c. It also borrows some punctuation marks such as '?' and '!' from Latin alphaugh Ethiopic alphabet has numeral system, the Arabic numeral system is rather monly used by Amharic.

ric Morphology aric has complex morphology where many words could be generated through al and derivational processes from other word forms. Many surface forms of n be formed from a base form through complex affixation, reduplication, and em interdigitation. Amharic words can be marked for a number of functions. ple, a verb can be marked for a combination of person, case, gender, number, ect, and mood. An Amharic word might take up to four prefixes and five suf-]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is d from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ /, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / rson singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural rker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands can be gener-ated from an Amharic root or its stems by changing the shape of in a stem or root, inserting vowels between root radicals, reduplicating one of ters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are stem templates for verbal words. However, all variants have a single root tion template. The major-ity of words in the language are generated from verbal ns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of m verbal roots usually rat 3 of 29 d in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it lt to create annotated corpus automatically. Moreover, there is lack of standard ce collection making it a major impediment to the development of Amharic IR and ools. The objective of this research work is: (1) to promote publicly accessible Amresources including a standard test collection for IR, morphologically annotated a and compiled stopwords list; and (2) to design Amharic IR system by investithe optimal representation of documents and queries considering both root-based em-based text representations. he rest of this paper is organized as follows. Section 2 describes Amharic language s morphology. Section 3 discusses related work. In Section 4, we present the pro-Amharic IR system architecture along with various options to represent Amharic ents and queries. Section 5 presents the evaluation framework of the proposed ric adhoc retrieval system including the presentation of the resources and corpora, mental setup, and experimental results. In Section 6, we present our conclusion t forward further research directions.

haric Language haric Writing System mharic is the working language of the government of Ethiopia currently having an ted population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken c language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in ia, Amharic is the lingua franca and the most literary language serving as a meof instruction in the education system of the country for a long period. Amharic thiopic alphabet and has 34 base characters along with modifications on the reve base characters. The alphabet is conveniently written in a tabular format of columns. The first column represents the basic form with vowel ኧ /ə/ and the other ers represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ d ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters s ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface , etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphalthough Ethiopic alphabet has numeral system, the Arabic numeral system is rather ommonly used by Amharic.

haric Morphology mharic has complex morphology where many words could be generated through ional and derivational processes from other word forms. Many surface forms of can be formed from a base form through complex affixation, reduplication, and c stem interdigitation. Amharic words can be marked for a number of functions. ample, a verb can be marked for a combination of person, case, gender, number, aspect, and mood. An Amharic word might take up to four prefixes and five suf- [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ucted from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ive/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / t person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands ds can be gener-ated from an Amharic root or its stems by changing the shape of ters in a stem or root, inserting vowels between root radicals, reduplicating one of aracters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are le stem templates for verbal words. However, all variants have a single root entation template. The major-ity of words in the language are generated from verbal Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of from verbal roots usually 'the state of something which is broken'/ 2.

/m s b r 3 of 29 ed in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it ult to create annotated corpus automatically. Moreover, there is lack of standard ence collection making it a major impediment to the development of Amharic IR and tools. The objective of this research work is: (1) to promote publicly accessible Amresources including a standard test collection for IR, morphologically annotated ra and compiled stopwords list; and (2) to design Amharic IR system by investig the optimal representation of documents and queries considering both root-based tem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language ts morphology. Section 3 discusses related work. In Section 4, we present the pro-Amharic IR system architecture along with various options to represent Amharic ments and queries. Section 5 presents the evaluation framework of the proposed aric adhoc retrieval system including the presentation of the resources and corpora, rimental setup, and experimental results. In Section 6, we present our conclusion ut forward further research directions.

haric Language mharic Writing System

Amharic is the working language of the government of Ethiopia currently having an ated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken tic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in pia, Amharic is the lingua franca and the most literary language serving as a meof instruction in the education system of the country for a long period. Amharic Ethiopic alphabet and has 34 base characters along with modifications on the reive base characters. The alphabet is conveniently written in a tabular format of columns. The first column represents the basic form with vowel ኧ /ə/ and the other ders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ nd ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own tuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface ), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphalthough Ethiopic alphabet has numeral system, the Arabic numeral system is rather commonly used by Amharic.

mharic Morphology

Amharic has complex morphology where many words could be generated through tional and derivational processes from other word forms. Many surface forms of s can be formed from a base form through complex affixation, reduplication, and tic stem interdigitation. Amharic words can be marked for a number of functions. xample, a verb can be marked for a combination of person, case, gender, number, , aspect, and mood. An Amharic word might take up to four prefixes and five suf- [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ tive/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / st person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural t marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands rds can be gener-ated from an Amharic root or its stems by changing the shape of cters in a stem or root, inserting vowels between root radicals, reduplicating one of haracters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are ple stem templates for verbal words. However, all variants have a single root sentation template. The major-ity of words in the language are generated from verbal . Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of s from verbal roots usually er is organized as follows. Section 2 describes Amharic language ction 3 discusses related work. In Section 4, we present the proem architecture along with various options to represent Amharic s. Section 5 presents the evaluation framework of the proposed l system including the presentation of the resources and corpora, d experimental results. In Section 6, we present our conclusion r research directions.

tem rking language of the government of Ethiopia currently having an f over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in e lingua franca and the most literary language serving as a methe education system of the country for a long period. Amharic and has 34 base characters along with modifications on the res. The alphabet is conveniently written in a tabular format of st column represents the basic form with vowel ኧ /ə/ and the nt modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / /ʔo/. For example, the base character በ /bə/ has the following /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are uch as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The n punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), colon), etc. It also borrows some punctuation marks such as '?' -bet. Although Ethiopic alphabet has numeral system, the Arabic r most commonly used by Amharic. lex morphology where many words could be generated through tional processes from other word forms. Many surface forms of rom a base form through complex affixation, reduplication, and sabari 'cause to break'/.

The document (Appendix A) is relevant to the four queries. The retrieval probability of the document in the case of stem-based matching is 0.032 for term query (1), 0.017 for (2), 0.004 for (3) and 0 for (4). However, in case of root-based matching, the retrieval probability of the document (at Appendix A) to the four queries is similar (0.057), which is better than stem-based matching. Furthermore, the stem-based text representation retrieves non-relevant documents since it may conflate semantically unrelated words.

We use Lemur toolkit for ranking. For a given query Q and a collection of retrieved documents D, the Lemur toolkit ranks retrieval results based on their possible relevance. It implements both BM25 and language modeling, where the document length is considered. BM25 ranks documents based on the following equation:

Score (D, Q) = n ∑ i=1 IDF(qi).
f (qi, D).(k1 + 1)

f (qi, D) + k1.(1 -b + b. |D| avgdl ) (10)
where f (qi,D) is q i 's term frequency in the document D, |D| is the length of the document D in words, and avgdl is the average document length in the text collection from which documents are drawn whereas k 1 and b are free parameters. IDF (q i ) is the inverse document frequency weight of the query term q i . From Equation [START_REF] Jackson | Natural Language Processing for Online Applications: Text Retrieval, Extraction and Categorization[END_REF], Score (D,Q) would be higher when query terms in Q have higher frequencies in document D. For each qi in Q, the following inequality holds true for Amharic documents.

f r (qi,D) >= f s (qi,D) >= f w (qi,D) (11)
where f r , f s , and f w denote term frequency in root-based, stem-based and word-based representations, respectively. Thus, it can be inferred that the root-based representation of queries and documents provide better information for ranking as f r (qi,D) provides the highest possible score. For language modeling, the similarity between a document D and a query Q is measured by the Kullback-Leibler (KL) divergence between the document model Dθ and the query model Qθ. The Kullback-Leibler (KL) divergence ranking function captures the term occurrence distributions and computed as:

KL (Qθ, Dθ) = ∑ w∈V p(w|Qθ) log p(w|Qθ) p(w|Dθ) ( 12
)
where w is word, v is word vector, p(w|Qθ) is estimated query term, p (w|Dθ) is the smoothed probability of a term seen in the document.

Experiment

Since Amharic IR test collection was unavailable, the first task of this research was to create such resource. We followed the TREC approach so that the general TREC evaluation framework could also be followed. We also compared the performance of the proposed system with that of previous studies and Google Amharic.

Corpora Preparation

Test Collection

Test collection plays a crucial role for designing, developing, and maintaining IR systems. However, test collection for Amharic adhoc IR did not exist. Thus, we created the first Amharic IR test collection named 2AIRTC and share it to the IR research community [START_REF] Getnet | Amharic information retrieval based on query expansion using semantic vocabulary[END_REF]. The test collection was created based on the framework used in TREC and Cranfield project.

The Amharic test collection contains representative documents and topics. The test collection consists of 12,583 documents, 240 topics and the corresponding relevance judgments. Documents were collected from Web, news agencies, and individuals. The topic set was created by considering both current issues and the topics that were likely to be treated in our initial corpus. They cover diverse issues and include short and medium topics in addition to collocation. The document relevance judgment was made manually by assessors using a precise guideline. We ran the title fields of the topics on our initial corpus using Lemur toolkit and Web using Google search engine to acquire a first retrieved document list of a maximum of 50 documents per topic. We fused both retrieved document list (Lemur LM and Google retrieval results) on our initial collection and Web documents for the complementary documents). Each document from the fused list was then judged for relevance. Furthermore, exhaustive relevance judgments were performed on some topics on the document collection to acquire more relevant documents. A document is marked as relevant based on the narrative information in the topic; thus, it should not simply contain words from a query but rather fulfill the information need. The summary of the test collection is presented in Table 6 and more details are available in [START_REF] Getnet | Amharic information retrieval based on query expansion using semantic vocabulary[END_REF]. Annotated corpora play significant role in the development of NLP tools and the evaluation of tasks such as IR. Morphological analysis is one of the fundamental NLP process to derive stem, root and grammatical parts of words based on its internal structure [START_REF] Gasser | Horn Morpho: A system for morphological processing of Amharic, Oromo, and Tigrinya[END_REF]. This could be carried out manually, automatically by NLP tools such as a morphological analyzer, or semi-automatically. The existing Amharic morphological analyzers are limited in scope and function, and are unsuitable for query and document processing. We created stem-based and root-based morphologically annotated corpora using semi-automatic method. These documents are part of our 2AIRTC collection. Each word in each document in the corpus are morphologically segmented into affixes and base (basic stems or roots). The stem and root extraction were performed by removing character(s), changing the shape of character, or simply segmenting stem from the rest of characters (affixes). Different word classes have different word structures during word formation, but many of them have prefix(s)-stem, stem-suffix(s), or prefix(s)-stem-suffix(s) word formation structures. The number of prefixes and suffixes varies from one to five [START_REF] Mulugeta | Learning morphological rules for Amharic verbs using inductive logic programming[END_REF]. The general structure of a morphologically annotated word W is:

[p_]* w [_s]*
where p is a prefix morpheme, "_" is a morphological segment marker, w is the root or stem of W, s is a suffix morpheme, [ . . . ] denotes optionality, and * denotes the possibility of multiple occurrence. For example, the verb /kalas limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually t lal f limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: [START_REF] Sanderson | The history of information retrieval research[END_REF] to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually n limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: [START_REF] Sanderson | The history of information retrieval research[END_REF] to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually bat Appl. Sci. 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually w limited in scope. The unavailability of full-fledged low-level Amharic NLP tools ma difficult to create annotated corpus automatically. Moreover, there is lack of stan reference collection making it a major impediment to the development of Amharic I NLP tools. The objective of this research work is: (1) to promote publicly accessible haric resources including a standard test collection for IR, morphologically anno corpora and compiled stopwords list; and (2) to design Amharic IR system by in gating the optimal representation of documents and queries considering both rootand stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic lang and its morphology. Section 3 discusses related work. In Section 4, we present the posed Amharic IR system architecture along with various options to represent Am documents and queries. Section 5 presents the evaluation framework of the prop Amharic adhoc retrieval system including the presentation of the resources and cor experimental setup, and experimental results. In Section 6, we present our concl and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently havi estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly sp Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spok Ethiopia, Amharic is the lingua franca and the most literary language serving as dium of instruction in the education system of the country for a long period. Am uses Ethiopic alphabet and has 34 base characters along with modifications on th spective base characters. The alphabet is conveniently written in a tabular form seven columns. The first column represents the basic form with vowel ኧ /ə/ and the six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modificatio /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized char such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (pr colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin a bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is r most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated thr inflectional and derivational processes from other word forms. Many surface for words can be formed from a base form through complex affixation, reduplication Semitic stem interdigitation. Amharic words can be marked for a number of func For example, a verb can be marked for a combination of person, case, gender, nu tense, aspect, and mood. An Amharic word might take up to four prefixes and fiv fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨn constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixe ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person p object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thou of words can be gener-ated from an Amharic root or its stems by changing the sha characters in a stem or root, inserting vowels between root radicals, reduplicating o the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. The multiple stem templates for verbal words. However, all variants have a single representation template. The major-ity of words in the language are generated from v roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivat words from verbal roots usually m limited in scope. The unavailability of full-fledged low-level Amharic NLP tools difficult to create annotated corpus automatically. Moreover, there is lack of s reference collection making it a major impediment to the development of Amhari NLP tools. The objective of this research work is: (1) to promote publicly accessi haric resources including a standard test collection for IR, morphologically an corpora and compiled stopwords list; and (2) to design Amharic IR system by gating the optimal representation of documents and queries considering both roo and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic la and its morphology. Section 3 discusses related work. In Section 4, we present posed Amharic IR system architecture along with various options to represent A documents and queries. Section 5 presents the evaluation framework of the p Amharic adhoc retrieval system including the presentation of the resources and experimental setup, and experimental results. In Section 6, we present our con and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently ha estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are sp Ethiopia, Amharic is the lingua franca and the most literary language serving a dium of instruction in the education system of the country for a long period. A uses Ethiopic alphabet and has 34 base characters along with modifications on spective base characters. The alphabet is conveniently written in a tabular fo seven columns. The first column represents the basic form with vowel ኧ /ə/ and t six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifica /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized ch such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' colon), etc. It also borrows some punctuation marks such as '?' and '!' from Lati bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated inflectional and derivational processes from other word forms. Many surface f words can be formed from a base form through complex affixation, reduplicat Semitic stem interdigitation. Amharic words can be marked for a number of fu For example, a verb can be marked for a combination of person, case, gender, n tense, aspect, and mood. An Amharic word might take up to four prefixes and fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨn constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffi ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third perso object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Th of words can be gener-ated from an Amharic root or its stems by changing the characters in a stem or root, inserting vowels between root radicals, reduplicatin the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. T multiple stem templates for verbal words. However, all variants have a sin representation template. The major-ity of words in the language are generated from roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The deriv words from verbal roots usually 'if we did not transfer for them [foc]'/ is morphologically segmented as follows. where p is a prefix morpheme, "_" is a morphological segment marker, w is the root or stem of W, s is a suffix morpheme, […] denotes optionality, and * denotes the possibility of multiple occurrence. For example, the verb ካላስተላለፍንባቸውም /kalasɨtəlaləfɨnɨbatʃəwɨmɨ 'if we did not transfer for them [foc]'/ is morphologically segmented as follows.

The first five morphemes are prefixes; አለፍ /ʔələfɨ/ is the basic stem whereas the last four morphemes are suffixes.

Stem-based corpus annotation: Majorities of Amharic words are composed of stems and attached affixes. Therefore, the stem-based morphological annotation segments word forms into more general representation known as basic stem and affixes. For example, the verb አልተለማመደም /ʔəlɨtələmamədəmɨ 'he did not practice'/, ረዣዥሞቹ /rəʒaʒɨmotʃu 'the longest ones'/, the adjective የብልሆችን /jəbɨlɨhotʃɨnɨ 'of intelligent [acc]'/, the verb በመሆኑ /bəməhonu 'since it happened'/, the noun በገንዘባችንና /bəgənɨzəbatʃɨnɨna 'through our money'/, and the functional word የሌሎቻችሁን /jəlelotʃatʃɨhunɨ 'of other [acc]'/ are annotated as indicated below.

አልተለማመደም የብልሆችን በመሆኑ አል_ተ_ለመድ_ኧ_ም የ_ብልህ_ኦች_ን በ_መ_ሆን_ኡ ʔəlɨ_tə_ləmədɨ_ə_mɨ jə_bɨlɨhɨ_ʔotʃɨ_nɨ bə_mə_honɨ_ʔu [neg]-[pas]-[stem]-[3,s,m]-[ncom] [gen]-[stem]-[p]-[acc] [pre]-[inf]-[stem]-[def] በገንዘባችንና የሌሎቻችሁን ረዣዥሞቹ በ_ገንዘብ_አችን_ና የ_ሌላ_ኦች_አችሁ_ን ረዥም_ኦች_ኡ
The first five morphemes are prefixes; / 2, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-l f Appl. Sci. 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually / is the basic stem whereas the last four morphemes are suffixes.

Stem-based corpus annotation: Majorities of Amharic words are composed of stems and attached affixes. Therefore, the stem-based morphological annotation segments word forms into more general representation known as basic stem and affixes. For example, the verb / 3 of 29 navailability of full-fledged low-level Amharic NLP tools makes it otated corpus automatically. Moreover, there is lack of standard king it a major impediment to the development of Amharic IR and ve of this research work is: (1) to promote publicly accessible Aming a standard test collection for IR, morphologically annotated stopwords list; and (2) to design Amharic IR system by investiresentation of documents and queries considering both root-based presentations. per is organized as follows. Section 2 describes Amharic language ection 3 discusses related work. In Section 4, we present the protem architecture along with various options to represent Amharic es. Section 5 presents the evaluation framework of the proposed al system including the presentation of the resources and corpora, nd experimental results. In Section 6, we present our conclusion er research directions. stem rking language of the government of Ethiopia currently having an of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken e world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in he lingua franca and the most literary language serving as a methe education system of the country for a long period. Amharic t and has 34 base characters along with modifications on the reers. The alphabet is conveniently written in a tabular format of irst column represents the basic form with vowel ኧ /ə/ and the sent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ኦ /ʔo/. For example, the base character በ /bə/ has the following ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The wn punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), e colon), etc. It also borrows some punctuation marks such as '?' a-bet. Although Ethiopic alphabet has numeral system, the Arabic er most commonly used by Amharic. y plex morphology where many words could be generated through ational processes from other word forms. Many surface forms of from a base form through complex affixation, reduplication, and l 3 of 29 scope. The unavailability of full-fledged low-level Amharic NLP tools makes it o create annotated corpus automatically. Moreover, there is lack of standard collection making it a major impediment to the development of Amharic IR and . The objective of this research work is: (1) to promote publicly accessible Amurces including a standard test collection for IR, morphologically annotated nd compiled stopwords list; and (2) to design Amharic IR system by investioptimal representation of documents and queries considering both root-based based text representations. est of this paper is organized as follows. Section 2 describes Amharic language orphology. Section 3 discusses related work. In Section 4, we present the proharic IR system architecture along with various options to represent Amharic ts and queries. Section 5 presents the evaluation framework of the proposed adhoc retrieval system including the presentation of the resources and corpora, tal setup, and experimental results. In Section 6, we present our conclusion rward further research directions.

ic Language ric Writing System aric is the working language of the government of Ethiopia currently having an population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken nguage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Amharic is the lingua franca and the most literary language serving as a menstruction in the education system of the country for a long period. Amharic pic alphabet and has 34 base characters along with modifications on the rease characters. The alphabet is conveniently written in a tabular format of mns. The first column represents the basic form with vowel ኧ /ə/ and the other represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ons such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface . It also borrows some punctuation marks such as '?' and '!' from Latin alphaugh Ethiopic alphabet has numeral system, the Arabic numeral system is rather monly used by Amharic.

ric Morphology aric has complex morphology where many words could be generated through al and derivational processes from other word forms. Many surface forms of be formed from a base form through complex affixation, reduplication, and em interdigitation. Amharic words can be marked for a number of functions. ple, a verb can be marked for a combination of person, case, gender, number, ect, and mood. An Amharic word might take up to four prefixes and five suf-]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is d from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ , ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / rson singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural rker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands can be gener-ated from an Amharic root or its stems by changing the shape of in a stem or root, inserting vowels between root radicals, reduplicating one of ters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are stem templates for verbal words. However, all variants have a single root tion template. The major-ity of words in the language are generated from verbal ns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of m verbal roots usually t l mam d m REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually 'he did not practice'/, R PEER REVIEW 16 of 29 using semi-automatic method. These documents are part of our 2AIRTC collection. Each word in each document in the corpus are morphologically segmented into affixes and base (basic stems or roots). The stem and root extraction were performed by removing character(s), changing the shape of character, or simply segmenting stem from the rest of characters (affixes). Different word classes have different word structures during word formation, but many of them have prefix(s)-stem, stem-suffix(s), or prefix(s)-stem-suffix(s) word formation structures. The number of prefixes and suffixes varies from one to five [START_REF] Mulugeta | Learning morphological rules for Amharic verbs using inductive logic programming[END_REF]. The general structure of a morphologically annotated word W is:

[p_]* w [_s]*
where p is a prefix morpheme, "_" is a morphological segment marker, w is the root or stem of W, s is a suffix morpheme, […] denotes optionality, and * denotes the possibility of multiple occurrence. For example, the verb ካላስተላለፍንባቸውም /kalasɨtəlaləfɨnɨbatʃəwɨmɨ 'if we did not transfer for them [foc]'/ is morphologically segmented as follows.

The first five morphemes are prefixes; አለፍ /ʔələfɨ/ is the basic stem whereas the last four morphemes are suffixes.

Stem-based corpus annotation: Majorities of Amharic words are composed of stems and attached affixes. Therefore, the stem-based morphological annotation segments word forms into more general representation known as basic stem and affixes. For example, the verb አልተለማመደም /ʔəlɨtələmamədəmɨ 'he did not practice'/, ረ ዣ ዥሞቹ / rəʒaʒɨmotʃu 'the longest ones'/, the adjective የብልሆችን /jəbɨlɨhotʃɨnɨ 'of intelligent [acc]'/, the verb በመሆኑ /bəməhonu 'since it happened'/, the noun በገንዘባችንና /bəgənɨzəbatʃɨnɨna 'through our money'/, and the functional word የሌሎቻችሁን /jəlelotʃatʃɨhunɨ 'of other [acc]'/ are annotated as indi-cated below. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

አልተለማመደም የብልሆችን በመሆኑ አል_ተ_ለመድ_ኧ_ም የ_ብልህ_ኦች_ን በ_መ_ሆን_ኡ ʔəlɨ_tə_ləmədɨ_ə_mɨ jə_bɨlɨhɨ_ʔotʃɨ_nɨ bə_mə_honɨ_ʔu [neg]-[pas]-[stem]-[3,s,m]-[ncom] [gen]-[stem]-[p]-[acc] [pre]-[inf]-[stem]-[def] በገንዘባችንና የሌሎቻችሁን ረዣዥሞቹ በ_ገንዘብ_አችን_ና የ_ሌላ_ኦች_አችሁ_ን ረዥም_ኦች_ኡ /r

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually mot Appl. Sci. 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually u 'the longest ones'/, the adjective /j b IEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually l VIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually ER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually n PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually z bat The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually 22, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually n 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually na 'through our money'/, and the functional word /j lelot PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually at FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually VIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of hun R REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of 'of other [acc]'/ are annotated as indicated below.

_ _ _ _ _ _ _ _ _ _
age of the government of Ethiopia currently having an million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken r Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in ranca and the most literary language serving as a meion system of the country for a long period. Amharic 4 base characters along with modifications on the rehabet is conveniently written in a tabular format of represents the basic form with vowel ኧ /ə/ and the cations with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / example, the base character በ /bə/ has the following ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The tions such as '።' (full stop), '፣' (comma), '፤' (semicolon), . It also borrows some punctuation marks such as '?' ugh Ethiopic alphabet has numeral system, the Arabic monly used by Amharic. ology where many words could be generated through esses from other word forms. Many surface forms of e form through complex affixation, reduplication, and aric words can be marked for a number of functions. ed for a combination of person, case, gender, number, aric word might take up to four prefixes and five suf-ላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed on/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciproərɨ 'tie'/); and four suffixes (ኩ /ku first person singular ቸው /ʔətʃəwɨ third person plural object marker for per-ና /na conjunction/). Thousands of words can be generstems by changing the shape of characters in a stem or t radicals, reduplicating one of the characters of the stem es on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for ts have a single root representation template. The majorenerated from verbal roots. Nouns, adjectives, and adoots. The derivation of words from verbal roots usually l gy plex morphology where many words could be generated through ational processes from other word forms. Many surface forms of from a base form through complex affixation, reduplication, and itation. Amharic words can be marked for a number of functions. can be marked for a combination of person, case, gender, number, od. An Amharic word might take up to four prefixes and five sufmple, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is r prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ar subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural -fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands r-ated from an Amharic root or its stems by changing the shape of r root, inserting vowels between root radicals, reduplicating one of stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are ates for verbal words. However, all variants have a single root te. The major-ity of words in the language are generated from verbal es, and ad-verbs can be derived from verbal roots. The derivation of ts usually _t _l m d Morphology ic has complex morphology where many words could be generated through and derivational processes from other word forms. Many surface forms of be formed from a base form through complex affixation, reduplication, and interdigitation. Amharic words can be marked for a number of functions. e, a verb can be marked for a combination of person, case, gender, number, t, and mood. An Amharic word might take up to four prefixes and five suf-For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / on singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural er for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands n be gener-ated from an Amharic root or its stems by changing the shape of a stem or root, inserting vowels between root radicals, reduplicating one of rs of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are m templates for verbal words. However, all variants have a single root on template. The major-ity of words in the language are generated from verbal s, adjectives, and ad-verbs can be derived from verbal roots. The derivation of verbal roots usually _ _m haric Morphology mharic has complex morphology where many words could be generated through ional and derivational processes from other word forms. Many surface forms of can be formed from a base form through complex affixation, reduplication, and c stem interdigitation. Amharic words can be marked for a number of functions. ample, a verb can be marked for a combination of person, case, gender, number, aspect, and mood. An Amharic word might take up to four prefixes and five suf- [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ucted from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ive/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / t person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands ds can be gener-ated from an Amharic root or its stems by changing the shape of ters in a stem or root, inserting vowels between root radicals, reduplicating one of aracters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are le stem templates for verbal words. However, all variants have a single root entation template. The major-ity of words in the language are generated from verbal Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of from verbal roots usually j _b

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually l 2.2.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually h

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually _

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually ot punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually _n

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually b _m _hon

Amharic Morphology

Amharic has complex morphology where many words could be generated throu inflectional and derivational processes from other word forms. Many surface forms words can be formed from a base form through complex affixation, reduplication, a Semitic stem interdigitation. Amharic words can be marked for a number of functio For example, a verb can be marked for a combination of person, case, gender, numb tense, aspect, and mood. An Amharic word might take up to four prefixes and five su fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plu object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousan of words can be gener-ated from an Amharic root or its stems by changing the shape characters in a stem or root, inserting vowels between root radicals, reduplicating one the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There a multiple stem templates for verbal words. However, all variants have a single ro representation template. The major-ity of words in the language are generated from verb roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation words from verbal roots usually _

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually

u [neg]-[pas]-[stem]-[3,s,m]-[ncom] [gen]-[stem]-[p]-[acc] [pre]-[inf]-[stem]-[def]

stem of W, s is a suffix morpheme, […] denotes optionality, and * denotes the possibility of multiple occurrence. For example, the verb ካላስተላለፍንባቸውም /kalasɨtəlaləfɨnɨbatʃəwɨmɨ 'if we did not transfer for them [foc]'/ is morphologically segmented as follows.

The first five morphemes are prefixes; አለፍ /ʔələfɨ/ is the basic stem whereas the last four morphemes are suffixes.

Stem-based corpus annotation: Majorities of Amharic words are composed of stems and attached affixes. Therefore, the stem-based morphological annotation segments word forms into more general representation known as basic stem and affixes. For example, the verb አልተለማመደም /ʔəlɨtələmamədəmɨ 'he did not practice'/, ረ ዣ ዥሞቹ / rəʒaʒɨmotʃu 'the longest ones'/, the adjective የብልሆችን /jəbɨlɨhotʃɨnɨ 'of intelligent [acc]'/, the verb በመሆኑ /bəməhonu 'since it happened'/, the noun በገንዘባችንና /bəgənɨzəbatʃɨnɨna 'through our money'/, and the functional word የሌሎቻችሁን /jəlelotʃatʃɨhunɨ 'of other [acc]'/ are annotated as indi-cated below.

አልተለማመደም

የብልሆችን በመሆኑ አል_ተ_ለመድ_ኧ_ም የ_ብልህ_ኦች_ን በ_መ_ሆን_ኡ ʔəlɨ_tə_ləmədɨ_ə_mɨ jə_bɨlɨhɨ_ʔotʃɨ_nɨ bə_mə_honɨ_ʔu

[neg]-[pas]-[stem]-[3,s,m]-[ncom] [gen]-[stem]-[p]-[acc] [pre]-[inf]-[stem]-[def]

በገንዘባችንና የሌሎቻችሁን ረዣዥሞቹ በ_ገንዘብ_አችን_ና የ_ሌላ_ኦች_አችሁ_ን ረዥም_ኦች_ኡ bə_gənɨzəbɨ_ʔətʃɨnɨ_na jə_lela_ʔotʃɨ_ʔətʃɨhu_nɨ rəʒɨmɨ_ʔotʃɨ_ʔu [pre]-[stem]-[1,

p,pos]-[conj] [gen]-[stem]-[p]-[2,p,pos]-[acc] [stem]-[p]-[def]

Root-based corpus annotation: Amharic roots are usually the base of stems and surface forms of words whereas stem is the base of surface forms of words. Thus, the origins of Amharic words are root rather than stems. Therefore, to analyses the impact of root for Amharic IR we created the root-based morphological annotated corpus which is part of 2AIRTC. Each word in each document is annotated morphologically for segmenting the root of each word from the rest of morphemes in a word. Therefore, the root-based corpus contains roots of words and their affixes. For instance, the verb ስላገዳደለቻቸው /sɨlagədadələcatʃəw 'since she makes them to kill each other'/ is annotated as 'ስለ_አ_ግ-ድ-ል_ኧች_አቸው /sɨlə_ʔə_gɨdɨl_ətʃɨ_ʔətʃəw/'. ስለ /sɨlə 'since'/ is preposition, አ /ʔə/ is causative, ግ-ድ-ል /g-d-l 'kill'/ is a root, ኧች /ətʃɨ/ and አቸው /ʔətʃəw/ are person markers. Similarly, other word classes are annotated. For example, the corresponding root-based annotations of sample words for which stem-based annotations are shown above are presented as follows.

_ _ _ _ _ _ _ _ _ b _g n
/mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface borrows some punctuation marks such as '?' and '!' from Latin alpha-iopic alphabet has numeral system, the Arabic numeral system is rather sed by Amharic. hology complex morphology where many words could be generated through erivational processes from other word forms. Many surface forms of ed from a base form through complex affixation, reduplication, and rdigitation. Amharic words can be marked for a number of functions. rb can be marked for a combination of person, case, gender, number, mood. An Amharic word might take up to four prefixes and five suf-example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ cipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / gular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands ener-ated from an Amharic root or its stems by changing the shape of m or root, inserting vowels between root radicals, reduplicating one of he stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are plates for verbal words. However, all variants have a single root plate. The major-ity of words in the language are generated from verbal ctives, and ad-verbs can be derived from verbal roots. The derivation of l roots usually

z b
a/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface lso borrows some punctuation marks such as '?' and '!' from Latin alpha-Ethiopic alphabet has numeral system, the Arabic numeral system is rather ly used by Amharic.

orphology has complex morphology where many words could be generated through d derivational processes from other word forms. Many surface forms of formed from a base form through complex affixation, reduplication, and nterdigitation. Amharic words can be marked for a number of functions. a verb can be marked for a combination of person, case, gender, number, and mood. An Amharic word might take up to four prefixes and five suf-or example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is om four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands be gener-ated from an Amharic root or its stems by changing the shape of stem or root, inserting vowels between root radicals, reduplicating one of of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root template. The major-ity of words in the language are generated from verbal adjectives, and ad-verbs can be derived from verbal roots. The derivation of rbal roots usually _ al system including the presentation of the resources and corpora, nd experimental results. In Section 6, we present our conclusion er research directions. stem orking language of the government of Ethiopia currently having an of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken e world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in he lingua franca and the most literary language serving as a methe education system of the country for a long period. Amharic t and has 34 base characters along with modifications on the reers. The alphabet is conveniently written in a tabular format of irst column represents the basic form with vowel ኧ /ə/ and the sent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ኦ /ʔo/. For example, the base character በ /bə/ has the following ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The wn punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), e colon), etc. It also borrows some punctuation marks such as '?' a-bet. Although Ethiopic alphabet has numeral system, the Arabic er most commonly used by Amharic. y plex morphology where many words could be generated through ational processes from other word forms. Many surface forms of from a base form through complex affixation, reduplication, and tation. Amharic words can be marked for a number of functions. an be marked for a combination of person, case, gender, number, d. An Amharic word might take up to four prefixes and five suf-, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprorb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular fect verb/, አቸው /ʔətʃəwɨ third person plural object marker for persative/, and ና /na conjunction/). Thousands of words can be generroot or its stems by changing the shape of characters in a stem or between root radicals, reduplicating one of the characters of the stem adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for r, all variants have a single root representation template. The majorguage are generated from verbal roots. Nouns, adjectives, and adrom verbal roots. The derivation of words from verbal roots usually t spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own tions such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface tc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-ough Ethiopic alphabet has numeral system, the Arabic numeral system is rather monly used by Amharic.

aric Morphology haric has complex morphology where many words could be generated through nal and derivational processes from other word forms. Many surface forms of an be formed from a base form through complex affixation, reduplication, and stem interdigitation. Amharic words can be marked for a number of functions.

ple, a verb can be marked for a combination of person, case, gender, number, pect, and mood. An Amharic word might take up to four prefixes and five suf-8]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ted from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ e/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / erson singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural arker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands s can be gener-ated from an Amharic root or its stems by changing the shape of rs in a stem or root, inserting vowels between root radicals, reduplicating one of acters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are stem templates for verbal words. However, all variants have a single root tation template. The major-ity of words in the language are generated from verbal ouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of om verbal roots usually n s ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface , etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-though Ethiopic alphabet has numeral system, the Arabic numeral system is rather ommonly used by Amharic.

haric Morphology mharic has complex morphology where many words could be generated through ional and derivational processes from other word forms. Many surface forms of can be formed from a base form through complex affixation, reduplication, and c stem interdigitation. Amharic words can be marked for a number of functions. ample, a verb can be marked for a combination of person, case, gender, number, aspect, and mood. An Amharic word might take up to four prefixes and five suf- [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ucted from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ive/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands ds can be gener-ated from an Amharic root or its stems by changing the shape of ters in a stem or root, inserting vowels between root radicals, reduplicating one of aracters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are le stem templates for verbal words. However, all variants have a single root entation template. The major-ity of words in the language are generated from verbal Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of from verbal roots usually _na j _lela_ Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually ot spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually _ Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually t spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually hu_n such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually r Z such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually m such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually _ Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually ot spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its o punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (pref colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alp bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rat most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated throu inflectional and derivational processes from other word forms. Many surface forms words can be formed from a base form through complex affixation, reduplication, a Semitic stem interdigitation. Amharic words can be marked for a number of functio For example, a verb can be marked for a combination of person, case, gender, numb tense, aspect, and mood. An Amharic word might take up to four prefixes and five s fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ / causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes ( ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plu object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousan of words can be gener-ated from an Amharic root or its stems by changing the shape characters in a stem or root, inserting vowels between root radicals, reduplicating one the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There multiple stem templates for verbal words. However, all variants have a single r representation template. The major-ity of words in the language are generated from ver roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation words from verbal roots usually _ Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually

u [pre]-[stem]-[1,p,pos]-[conj] [gen]-[stem]-[p]-[2,p,pos]-[acc] [stem]-[p]-[def]
Root-based corpus annotation: Amharic roots are usually the base of stems and surface forms of words whereas stem is the base of surface forms of words. Thus, the origins of Amharic words are root rather than stems. Therefore, to analyses the impact of root for Amharic IR we created the root-based morphological annotated corpus which is part of 2AIRTC. Each word in each document is annotated morphologically for segmenting the root of each word from the rest of morphemes in a word. Therefore, the rootbased corpus contains roots of words and their affixes. For instance, the verb /s f over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in e lingua franca and the most literary language serving as a me-the education system of the country for a long period. Amharic and has 34 base characters along with modifications on the re-rs. The alphabet is conveniently written in a tabular format of t column represents the basic form with vowel ኧ /ə/ and the other difications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ple, the base character በ /bə/ has the following modifications: ቡ e/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters a/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface ws some punctuation marks such as '?' and '!' from Latin alpha-alphabet has numeral system, the Arabic numeral system is rather y Amharic. lex morphology where many words could be generated through tional processes from other word forms. Many surface forms of rom a base form through complex affixation, reduplication, and ation. Amharic words can be marked for a number of functions. n be marked for a combination of person, case, gender, number, d. An Amharic word might take up to four prefixes and five suf-ple, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ -cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural ective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands ated from an Amharic root or its stems by changing the shape of root, inserting vowels between root radicals, reduplicating one of m or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are es for verbal words. However, all variants have a single root . The major-ity of words in the language are generated from verbal , and ad-verbs can be derived from verbal roots. The derivation of usually lag dad l cat Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually w 'since she makes them to kill each other'/ is annotated as ' _ _ --_ _ /s ic is the working language of the government of Ethiopia currently having an opulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken uage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in mharic is the lingua franca and the most literary language serving as a me-truction in the education system of the country for a long period. Amharic ic alphabet and has 34 base characters along with modifications on the re-se characters. The alphabet is conveniently written in a tabular format of ns. The first column represents the basic form with vowel ኧ /ə/ and the other present modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ o/. For example, the base character በ /bə/ has the following modifications: ቡ ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own s such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface It also borrows some punctuation marks such as '?' and '!' from Latin alpha-h Ethiopic alphabet has numeral system, the Arabic numeral system is rather only used by Amharic.

Morphology

ic has complex morphology where many words could be generated through and derivational processes from other word forms. Many surface forms of be formed from a base form through complex affixation, reduplication, and interdigitation. Amharic words can be marked for a number of functions. e, a verb can be marked for a combination of person, case, gender, number, t, and mood. An Amharic word might take up to four prefixes and five suf-For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / on singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural er for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands n be gener-ated from an Amharic root or its stems by changing the shape of a stem or root, inserting vowels between root radicals, reduplicating one of rs of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are m templates for verbal words. However, all variants have a single root on template. The major-ity of words in the language are generated from verbal s, adjectives, and ad-verbs can be derived from verbal roots. The derivation of verbal roots usually l _ annotated corpus automatically. Moreover, there is lack of standard n making it a major impediment to the development of Amharic IR and jective of this research work is: (1) to promote publicly accessible Amcluding a standard test collection for IR, morphologically annotated iled stopwords list; and (2) to design Amharic IR system by investil representation of documents and queries considering both root-based xt representations. is paper is organized as follows. Section 2 describes Amharic language gy. Section 3 discusses related work. In Section 4, we present the prosystem architecture along with various options to represent Amharic ueries. Section 5 presents the evaluation framework of the proposed rieval system including the presentation of the resources and corpora, p, and experimental results. In Section 6, we present our conclusion urther research directions. age ng System e working language of the government of Ethiopia currently having an tion of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in c is the lingua franca and the most literary language serving as a men in the education system of the country for a long period. Amharic habet and has 34 base characters along with modifications on the reracters. The alphabet is conveniently written in a tabular format of he first column represents the basic form with vowel ኧ /ə/ and the epresent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / and ኦ /ʔo/. For example, the base character በ /bə/ has the following /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are ers such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), eface colon), etc. It also borrows some punctuation marks such as '?' alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic rather most commonly used by Amharic. hology complex morphology where many words could be generated through erivational processes from other word forms. Many surface forms of ed from a base form through complex affixation, reduplication, and digitation. Amharic words can be marked for a number of functions. rb can be marked for a combination of person, case, gender, number, mood. An Amharic word might take up to four prefixes and five sufple, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciproe verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular r perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for peraccusative/, and ና /na conjunction/). Thousands of words can be generaric root or its stems by changing the shape of characters in a stem or els between root radicals, reduplicating one of the characters of the stem by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for ever, all variants have a single root representation template. The majore language are generated from verbal roots. Nouns, adjectives, and aded from verbal roots. The derivation of words from verbal roots usually _g Amharic is the working language of the government of Ethiopia currently having an mated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken itic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in iopia, Amharic is the lingua franca and the most literary language serving as a me-m of instruction in the education system of the country for a long period. Amharic s Ethiopic alphabet and has 34 base characters along with modifications on the re-ctive base characters. The alphabet is conveniently written in a tabular format of en columns. The first column represents the basic form with vowel ኧ /ə/ and the other orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ , ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters h as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface n), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather t commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through ectional and derivational processes from other word forms. Many surface forms of ds can be formed from a base form through complex affixation, reduplication, and itic stem interdigitation. Amharic words can be marked for a number of functions. example, a verb can be marked for a combination of person, case, gender, number, e, aspect, and mood. An Amharic word might take up to four prefixes and five suf-s [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is structed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ sative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / irst person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural ct marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands ords can be gener-ated from an Amharic root or its stems by changing the shape of racters in a stem or root, inserting vowels between root radicals, reduplicating one of characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are ltiple stem templates for verbal words. However, all variants have a single root resentation template. The major-ity of words in the language are generated from verbal ts. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of ds from verbal roots usually d Amharic is the working language of the government of Ethiopia currently having an timated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken mitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in hiopia, Amharic is the lingua franca and the most literary language serving as a me-um of instruction in the education system of the country for a long period. Amharic es Ethiopic alphabet and has 34 base characters along with modifications on the re-ective base characters. The alphabet is conveniently written in a tabular format of ven columns. The first column represents the basic form with vowel ኧ /ə/ and the other x orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ u/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters ch as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own nctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface lon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-t. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather ost commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through flectional and derivational processes from other word forms. Many surface forms of ords can be formed from a base form through complex affixation, reduplication, and mitic stem interdigitation. Amharic words can be marked for a number of functions. r example, a verb can be marked for a combination of person, case, gender, number, nse, aspect, and mood. An Amharic word might take up to four prefixes and five suf-xes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is nstructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ usative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural ject marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands words can be gener-ated from an Amharic root or its stems by changing the shape of aracters in a stem or root, inserting vowels between root radicals, reduplicating one of e characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are ultiple stem templates for verbal words. However, all variants have a single root presentation template. The major-ity of words in the language are generated from verbal ots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of ords from verbal roots usually l_ t documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually _ cult to create annotated corpus automatically. Moreover, there is lack of standard rence collection making it a major impediment to the development of Amharic IR and tools. The objective of this research work is: (1) to promote publicly accessible Amc resources including a standard test collection for IR, morphologically annotated ora and compiled stopwords list; and (2) to design Amharic IR system by investing the optimal representation of documents and queries considering both root-based stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language its morphology. Section 3 discusses related work. In Section 4, we present the prod Amharic IR system architecture along with various options to represent Amharic ments and queries. Section 5 presents the evaluation framework of the proposed haric adhoc retrieval system including the presentation of the resources and corpora, rimental setup, and experimental results. In Section 6, we present our conclusion put forward further research directions. mharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an ated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken itic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in opia, Amharic is the lingua franca and the most literary language serving as a meof instruction in the education system of the country for a long period. Amharic Ethiopic alphabet and has 34 base characters along with modifications on the retive base characters. The alphabet is conveniently written in a tabular format of n columns. The first column represents the basic form with vowel ኧ /ə/ and the r six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following ifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are alized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The uage has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic eral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through ctional and derivational processes from other word forms. Many surface forms of ds can be formed from a base form through complex affixation, reduplication, and itic stem interdigitation. Amharic words can be marked for a number of functions. example, a verb can be marked for a combination of person, case, gender, number, e, aspect, and mood. An Amharic word might take up to four prefixes and five suf- [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-; the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular ect marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perve verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generfrom an Amharic root or its stems by changing the shape of characters in a stem or , inserting vowels between root radicals, reduplicating one of the characters of the stem ord itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for al words. However, all variants have a single root representation template. The majorf words in the language are generated from verbal roots. Nouns, adjectives, and ads can be derived from verbal roots. The derivation of words from verbal roots usually t documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually w/'. /s Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually l 'since'/ is preposition, / difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually / is causative, --/g-d-l 'kill'/ is a root, / t posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually / and / limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually t posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually w/ are person markers. Similarly, other word classes are annotated. For example, the corresponding root-based annotations of sample words for which stem-based annotations are shown above are presented as follows.

_ _ --_ _ _ _ _ _ _ --_ 3 of 29
y of full-fledged low-level Amharic NLP tools makes it us automatically. Moreover, there is lack of standard ajor impediment to the development of Amharic IR and search work is: (1) to promote publicly accessible Amard test collection for IR, morphologically annotated list; and (2) to design Amharic IR system by investiof documents and queries considering both root-based ns. nized as follows. Section 2 describes Amharic language cusses related work. In Section 4, we present the procture along with various options to represent Amharic 5 presents the evaluation framework of the proposed cluding the presentation of the resources and corpora, ental results. In Section 6, we present our conclusion directions.

age of the government of Ethiopia currently having an million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken r Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in ranca and the most literary language serving as a meion system of the country for a long period. Amharic 4 base characters along with modifications on the rehabet is conveniently written in a tabular format of represents the basic form with vowel ኧ /ə/ and the cations with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / example, the base character በ /bə/ has the following ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The tions such as '።' (full stop), '፣' (comma), '፤' (semicolon), . It also borrows some punctuation marks such as '?' ugh Ethiopic alphabet has numeral system, the Arabic monly used by Amharic. ology where many words could be generated through esses from other word forms. Many surface forms of e form through complex affixation, reduplication, and aric words can be marked for a number of functions. ed for a combination of person, case, gender, number, aric word might take up to four prefixes and five suf-ላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed on/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciproərɨ 'tie'/); and four suffixes (ኩ /ku first person singular ቸው /ʔətʃəwɨ third person plural object marker for per-ና /na conjunction/). Thousands of words can be generstems by changing the shape of characters in a stem or t radicals, reduplicating one of the characters of the stem es on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for ts have a single root representation template. The majorenerated from verbal roots. Nouns, adjectives, and adoots. The derivation of words from verbal roots usually l al system including the presentation of the resources and corpora, nd experimental results. In Section 6, we present our conclusion er research directions. ystem orking language of the government of Ethiopia currently having an of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken he world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in the lingua franca and the most literary language serving as a me-n the education system of the country for a long period. Amharic et and has 34 base characters along with modifications on the re-ters. The alphabet is conveniently written in a tabular format of irst column represents the basic form with vowel ኧ /ə/ and the other odifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ample, the base character በ /bə/ has the following modifications: ቡ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters wa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface rows some punctuation marks such as '?' and '!' from Latin alpha-c alphabet has numeral system, the Arabic numeral system is rather by Amharic.

gy plex morphology where many words could be generated through ational processes from other word forms. Many surface forms of from a base form through complex affixation, reduplication, and itation. Amharic words can be marked for a number of functions. can be marked for a combination of person, case, gender, number, od. An Amharic word might take up to four prefixes and five suf-mple, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is r prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ar subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural -fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands r-ated from an Amharic root or its stems by changing the shape of r root, inserting vowels between root radicals, reduplicating one of stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are ates for verbal words. However, all variants have a single root te. The major-ity of words in the language are generated from verbal es, and ad-verbs can be derived from verbal roots. The derivation of ts usually _t _l-m-d_ _m ic adhoc retrieval system including the presentation of the resources and corpora, ental setup, and experimental results. In Section 6, we present our conclusion t forward further research directions.

aric Language haric Writing System haric is the working language of the government of Ethiopia currently having an ed population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in a, Amharic is the lingua franca and the most literary language serving as a me-f instruction in the education system of the country for a long period. Amharic hiopic alphabet and has 34 base characters along with modifications on the re-e base characters. The alphabet is conveniently written in a tabular format of olumns. The first column represents the basic form with vowel ኧ /ə/ and the other rs represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-hough Ethiopic alphabet has numeral system, the Arabic numeral system is rather mmonly used by Amharic.

haric Morphology haric has complex morphology where many words could be generated through nal and derivational processes from other word forms. Many surface forms of can be formed from a base form through complex affixation, reduplication, and stem interdigitation. Amharic words can be marked for a number of functions. mple, a verb can be marked for a combination of person, case, gender, number, spect, and mood. An Amharic word might take up to four prefixes and five suf-18]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is cted from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ e/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural arker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands s can be gener-ated from an Amharic root or its stems by changing the shape of rs in a stem or root, inserting vowels between root radicals, reduplicating one of racters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are e stem templates for verbal words. However, all variants have a single root ntation template. The major-ity of words in the language are generated from verbal ouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of rom verbal roots usually j _b Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually l Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually h Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually _ OR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually ot reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually _n Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually b _m _h-w-n_ Appl. Sci. 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually

u [neg]-[pas]-[root]-[3,s,m]-[ncom] [gen]-[root]-[p]-[acc] [pre]-[inf]-[root]-[def]
ppl. Sci. 2022, 12, x FOR PEER REVIEW 16 of 29 using semi-automatic method. These documents are part of our 2AIRTC collection. Each word in each document in the corpus are morphologically segmented into affixes and base (basic stems or roots). The stem and root extraction were performed by removing character(s), changing the shape of character, or simply segmenting stem from the rest of characters (affixes). Different word classes have different word structures during word formation, but many of them have prefix(s)-stem, stem-suffix(s), or prefix(s)-stem-suffix(s) word formation structures. The number of prefixes and suffixes varies from one to five [START_REF] Mulugeta | Learning morphological rules for Amharic verbs using inductive logic programming[END_REF]. The general structure of a morphologically annotated word W is:

[p_]* w [_s]*
where p is a prefix morpheme, "_" is a morphological segment marker, w is the root or stem of W, s is a suffix morpheme, […] denotes optionality, and * denotes the possibility of multiple occurrence. For example, the verb ካላስተላለፍንባቸውም /kalasɨtəlaləfɨnɨbatʃəwɨmɨ 'if we did not transfer for them [foc]'/ is morphologically segmented as follows.

The first five morphemes are prefixes; አለፍ /ʔələfɨ/ is the basic stem whereas the last four morphemes are suffixes.

Stem-based corpus annotation: Majorities of Amharic words are composed of stems and attached affixes. Therefore, the stem-based morphological annotation segments word forms into more general representation known as basic stem and affixes. For example, the verb አልተለማመደም /ʔəlɨtələmamədəmɨ 'he did not practice'/, ረ ዣ ዥሞቹ / rəʒaʒɨmotʃu 'the longest ones'/, the adjective የብልሆችን /jəbɨlɨhotʃɨnɨ 'of intelligent [acc]'/, the verb በመሆኑ /bəməhonu 'since it happened'/, the noun በገንዘባችንና /bəgənɨzəbatʃɨnɨna 'through our money'/, and the functional word የሌሎቻችሁን /jəlelotʃatʃɨhunɨ 'of other [acc]'/ are annotated as indi-cated below.

አልተለማመደም የብልሆችን በመሆኑ አል_ተ_ለመድ_ኧ_ም የ_ብልህ_ኦች_ን በ_መ_ሆን_ኡ ʔəlɨ_tə_ləmədɨ_ə_mɨ jə_bɨlɨhɨ_ʔotʃɨ_nɨ bə_mə_honɨ_ʔu [

neg]-[pas]-[stem]-[3,s,m]-[ncom] [gen]-[stem]-[p]-[acc]

[pre]-

[inf]-[stem]-[def] በገንዘባችንና የሌሎቻችሁን ረዣዥሞቹ በ_ገንዘብ_አችን_ና የ_ሌላ_ኦች_አችሁ_ን ረዥም_ኦች_ኡ bə_gənɨzəbɨ_ʔətʃɨnɨ_na jə_lela_ʔotʃɨ_ʔətʃɨhu_nɨ rəʒɨmɨ_ʔotʃɨ_ʔu [pre]-[stem]-[1,

p,pos]-[conj] [gen]-[stem]-[p]-[2,p,pos]-[acc] [stem]-[p]-[def]

Root-based corpus annotation: Amharic roots are usually the base of stems and surface forms of words whereas stem is the base of surface forms of words. Thus, the origins of Amharic words are root rather than stems. Therefore, to analyses the impact of root for Amharic IR we created the root-based morphological annotated corpus which is part of 2AIRTC. Each word in each document is annotated morphologically for segmenting the root of each word from the rest of morphemes in a word. Therefore, the root-based corpus contains roots of words and their affixes. For instance, the verb ስላገዳደለቻቸው /sɨlagədadələcatʃəw 'since she makes them to kill each other'/ is annotated as 'ስለ_አ_ግ-ድ-ል_ኧች_አቸው /sɨlə_ʔə_gɨdɨl_ətʃɨ_ʔətʃəw/'. ስለ /sɨlə 'since'/ is preposition, አ /ʔə/ is causative, ግ-ድ-ል /g-d-l 'kill'/ is a root, ኧች /ətʃɨ/ and አቸው /ʔətʃəw/ are person markers. Similarly, other word classes are annotated. For example, the corresponding root-based annotations of sample words for which stem-based annotations are shown above are presented as follows.

_ _ _ _ _ _ _ --_ _ b _g n xt representations.
is paper is organized as follows. Section 2 describes Amharic language gy. Section 3 discusses related work. In Section 4, we present the pro-system architecture along with various options to represent Amharic ueries. Section 5 presents the evaluation framework of the proposed rieval system including the presentation of the resources and corpora, p, and experimental results. In Section 6, we present our conclusion urther research directions.

age

ng System e working language of the government of Ethiopia currently having an tion of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in c is the lingua franca and the most literary language serving as a me-n in the education system of the country for a long period. Amharic habet and has 34 base characters along with modifications on the re-racters. The alphabet is conveniently written in a tabular format of e first column represents the basic form with vowel ኧ /ə/ and the other nt modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ example, the base character በ /bə/ has the following modifications: ቡ , ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface borrows some punctuation marks such as '?' and '!' from Latin alpha-iopic alphabet has numeral system, the Arabic numeral system is rather sed by Amharic.

hology complex morphology where many words could be generated through erivational processes from other word forms. Many surface forms of ed from a base form through complex affixation, reduplication, and rdigitation. Amharic words can be marked for a number of functions. rb can be marked for a combination of person, case, gender, number, mood. An Amharic word might take up to four prefixes and five suf-example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ cipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / gular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands ener-ated from an Amharic root or its stems by changing the shape of m or root, inserting vowels between root radicals, reduplicating one of he stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are plates for verbal words. However, all variants have a single root plate. The major-ity of words in the language are generated from verbal ctives, and ad-verbs can be derived from verbal roots. The derivation of l roots usually z b d text representations. f this paper is organized as follows. Section 2 describes Amharic language ology. Section 3 discusses related work. In Section 4, we present the pro-c IR system architecture along with various options to represent Amharic d queries. Section 5 presents the evaluation framework of the proposed retrieval system including the presentation of the resources and corpora, setup, and experimental results. In Section 6, we present our conclusion rd further research directions.

nguage riting System

is the working language of the government of Ethiopia currently having an ulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken ge in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in aric is the lingua franca and the most literary language serving as a me-ction in the education system of the country for a long period. Amharic alphabet and has 34 base characters along with modifications on the re-characters. The alphabet is conveniently written in a tabular format of . The first column represents the basic form with vowel ኧ /ə/ and the other esent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ For example, the base character በ /bə/ has the following modifications: ቡ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters a/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface lso borrows some punctuation marks such as '?' and '!' from Latin alpha-Ethiopic alphabet has numeral system, the Arabic numeral system is rather ly used by Amharic. orphology has complex morphology where many words could be generated through d derivational processes from other word forms. Many surface forms of formed from a base form through complex affixation, reduplication, and nterdigitation. Amharic words can be marked for a number of functions. a verb can be marked for a combination of person, case, gender, number, and mood. An Amharic word might take up to four prefixes and five suf-or example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is om four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands be gener-ated from an Amharic root or its stems by changing the shape of stem or root, inserting vowels between root radicals, reduplicating one of of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root template. The major-ity of words in the language are generated from verbal adjectives, and ad-verbs can be derived from verbal roots. The derivation of rbal roots usually

_ 3 of 29
navailability of full-fledged low-level Amharic NLP tools makes it otated corpus automatically. Moreover, there is lack of standard king it a major impediment to the development of Amharic IR and ve of this research work is: (1) to promote publicly accessible Aming a standard test collection for IR, morphologically annotated stopwords list; and (2) to design Amharic IR system by investiresentation of documents and queries considering both root-based presentations. per is organized as follows. Section 2 describes Amharic language ection 3 discusses related work. In Section 4, we present the protem architecture along with various options to represent Amharic es. Section 5 presents the evaluation framework of the proposed al system including the presentation of the resources and corpora, nd experimental results. In Section 6, we present our conclusion er research directions. stem rking language of the government of Ethiopia currently having an of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken e world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in he lingua franca and the most literary language serving as a methe education system of the country for a long period. Amharic t and has 34 base characters along with modifications on the rers. The alphabet is conveniently written in a tabular format of irst column represents the basic form with vowel ኧ /ə/ and the sent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ኦ /ʔo/. For example, the base character በ /bə/ has the following ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The wn punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), colon), etc. It also borrows some punctuation marks such as '?' a-bet. Although Ethiopic alphabet has numeral system, the Arabic er most commonly used by Amharic. y plex morphology where many words could be generated through ational processes from other word forms. Many surface forms of from a base form through complex affixation, reduplication, and tation. Amharic words can be marked for a number of functions. an be marked for a combination of person, case, gender, number, d. An Amharic word might take up to four prefixes and five suf-, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprorb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular fect verb/, አቸው /ʔətʃəwɨ third person plural object marker for persative/, and ና /na conjunction/). Thousands of words can be generroot or its stems by changing the shape of characters in a stem or etween root radicals, reduplicating one of the characters of the stem adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for r, all variants have a single root representation template. The majorguage are generated from verbal roots. Nouns, adjectives, and adom verbal roots. The derivation of words from verbal roots usually t EW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually -based text representations. rest of this paper is organized as follows. Section 2 describes Amharic language orphology. Section 3 discusses related work. In Section 4, we present the pro-mharic IR system architecture along with various options to represent Amharic ts and queries. Section 5 presents the evaluation framework of the proposed adhoc retrieval system including the presentation of the resources and corpora, ental setup, and experimental results. In Section 6, we present our conclusion forward further research directions.

ric Language aric Writing System haric is the working language of the government of Ethiopia currently having an d population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken anguage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in , Amharic is the lingua franca and the most literary language serving as a me-instruction in the education system of the country for a long period. Amharic iopic alphabet and has 34 base characters along with modifications on the re-base characters. The alphabet is conveniently written in a tabular format of lumns. The first column represents the basic form with vowel ኧ /ə/ and the other s represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ i/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own tions such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface tc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-ough Ethiopic alphabet has numeral system, the Arabic numeral system is rather monly used by Amharic.

aric Morphology haric has complex morphology where many words could be generated through al and derivational processes from other word forms. Many surface forms of n be formed from a base form through complex affixation, reduplication, and tem interdigitation. Amharic words can be marked for a number of functions. ple, a verb can be marked for a combination of person, case, gender, number, pect, and mood. An Amharic word might take up to four prefixes and five suf-8]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ted from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ e/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / erson singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural arker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands can be gener-ated from an Amharic root or its stems by changing the shape of s in a stem or root, inserting vowels between root radicals, reduplicating one of cters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are stem templates for verbal words. However, all variants have a single root tation template. The major-ity of words in the language are generated from verbal uns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of om verbal roots usually n m-based text representations. e rest of this paper is organized as follows. Section 2 describes Amharic language morphology. Section 3 discusses related work. In Section 4, we present the pro-Amharic IR system architecture along with various options to represent Amharic ents and queries. Section 5 presents the evaluation framework of the proposed ic adhoc retrieval system including the presentation of the resources and corpora, ental setup, and experimental results. In Section 6, we present our conclusion t forward further research directions. aric Language haric Writing System mharic is the working language of the government of Ethiopia currently having an ted population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken c language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in ia, Amharic is the lingua franca and the most literary language serving as a me-f instruction in the education system of the country for a long period. Amharic thiopic alphabet and has 34 base characters along with modifications on the re-e base characters. The alphabet is conveniently written in a tabular format of olumns. The first column represents the basic form with vowel ኧ /ə/ and the other ers represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters s ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-though Ethiopic alphabet has numeral system, the Arabic numeral system is rather ommonly used by Amharic.

haric Morphology mharic has complex morphology where many words could be generated through onal and derivational processes from other word forms. Many surface forms of can be formed from a base form through complex affixation, reduplication, and c stem interdigitation. Amharic words can be marked for a number of functions. ample, a verb can be marked for a combination of person, case, gender, number, aspect, and mood. An Amharic word might take up to four prefixes and five suf- [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is cted from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ive/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands ds can be gener-ated from an Amharic root or its stems by changing the shape of ters in a stem or root, inserting vowels between root radicals, reduplicating one of racters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are le stem templates for verbal words. However, all variants have a single root ntation template. The major-ity of words in the language are generated from verbal ouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of from verbal roots usually _na j _lela_ R PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually hu_n and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually r-Z-m_ Appl. Sci. 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic langua and its morphology. Section 3 discusses related work. In Section 4, we present the pr posed Amharic IR system architecture along with various options to represent Amha documents and queries. Section 5 presents the evaluation framework of the propos Amharic adhoc retrieval system including the presentation of the resources and corpo experimental setup, and experimental results. In Section 6, we present our conclusi and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spok Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken Ethiopia, Amharic is the lingua franca and the most literary language serving as a m dium of instruction in the education system of the country for a long period. Amha uses Ethiopic alphabet and has 34 base characters along with modifications on the r spective base characters. The alphabet is conveniently written in a tabular format seven columns. The first column represents the basic form with vowel ኧ /ə/ and the oth six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characte such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its ow punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (prefa colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alph bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rath most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated throu inflectional and derivational processes from other word forms. Many surface forms words can be formed from a base form through complex affixation, reduplication, an Semitic stem interdigitation. Amharic words can be marked for a number of function For example, a verb can be marked for a combination of person, case, gender, numb tense, aspect, and mood. An Amharic word might take up to four prefixes and five su fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plur object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousan of words can be gener-ated from an Amharic root or its stems by changing the shape characters in a stem or root, inserting vowels between root radicals, reduplicating one the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There a multiple stem templates for verbal words. However, all variants have a single ro representation template. The major-ity of words in the language are generated from verb roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually The root representation of words derived from verbal root is slightly different from non-verbal root. Roots of verbal are represented by radicals but might not in case of nonverbal roots. On the other hand, the stem and root of non-verbs have similar representation. However, the stems and roots of verbs are different. The details of them are presented in Table 7. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

2.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

2.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

2.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

2.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually kara/ strong ---/n g r Sci. 2022, 12, x FOR PEER REVIEW 4 of 29 involves stem formation followed by word formation. Amharic roots are the base of stems which in turn are the base of many surface forms of words (see Table 1). Amharic verbal stems are formed from verbal roots by inserting vowels between radicals (consonants). For example, the verbal stems ንገር /nɨgərɨ/, ላመድ /lamədɨ/ and ሰከር /səkərɨ/ are derived from the verbal roots ን-ግ-ር /n-b-r/, ል-ም-ድ /l-m-d/ and ስ-ክ-ር /s-k-r/, respectively. The patterns of these stem formations from the roots are ን-እ-ግ-ኧ-ር /n-ɨ-g-ə-r-ɨ/, ል-ኣ-ም-ኧ-ድ /l-a-m-ə-d-ɨ/, and ሰ-ኧ-ከ-ኧ-ር /s-ə-k-ə-r-ɨ/, respectively. Here ን /n/, ግ /g/, ር /r/, ል /l/, ም /m/, ድ /d/, ስ /s/, ክ /k/ and ር /r/ are consonants (C) whereas እ, ኧ, and ኣ are vowels (V). Depending on the types of verbs, stems are produced based on template structures in various forms such as perfective, imperfective, jussive, imperative, etc. [START_REF] Yifru | Morphology-Based Language Modeling for Amharic[END_REF]. For example, the template structures of tri-radicals verb types is presented in Table 2.

x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

2.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually OR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language nd its morphology. Section 3 discusses related work. In Section 4, we present the proosed Amharic IR system architecture along with various options to represent Amharic ocuments and queries. Section 5 presents the evaluation framework of the proposed mharic adhoc retrieval system including the presentation of the resources and corpora, xperimental setup, and experimental results. In Section 6, we present our conclusion nd put forward further research directions. . Amharic Language .1. Amharic Writing System Amharic is the working language of the government of Ethiopia currently having an stimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken emitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in thiopia, Amharic is the lingua franca and the most literary language serving as a meium of instruction in the education system of the country for a long period. Amharic ses Ethiopic alphabet and has 34 base characters along with modifications on the reective base characters. The alphabet is conveniently written in a tabular format of ven columns.

The first column represents the basic form with vowel ኧ /ə/ and the ther six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / /, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following odifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are bialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The nguage has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), ' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' nd '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic umeral system is rather most commonly used by Amharic.

.

Amharic Morphology

Amharic has complex morphology where many words could be generated through flectional and derivational processes from other word forms. Many surface forms of ords can be formed from a base form through complex affixation, reduplication, and emitic stem interdigitation. Amharic words can be marked for a number of functions. or example, a verb can be marked for a combination of person, case, gender, number, nse, aspect, and mood. An Amharic word might take up to four prefixes and five suf- The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually involves stem formation followed by word formation. Amharic roots are the base of stems which in turn are the base of many surface forms of words (see Table 1). The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually The stem-based and root-based corpora annotations were performed using stem-based and root-based lexicons, respectively. The lexicons were annotated manually whereas documents in the corpus were annotated automatically. Each lexicon contains surface words and their respective annotation forms. Each word in each document was replaced by the corresponding morphologically annotated form using Algorithm 1.

Implementation and Measures

Various experiments were carried out after creating morphologically annotated Amharic text corpora which could be used as benchmarks for developing and evaluating the performance of IR and NLP systems. Python was used for the preprocessing tasks, while indexing and retrieving were performed using Lemur toolkit. The retrieval effectiveness was evaluated automatically using trec_eval tool. Precision-recall curves, precision (P) at a certain level of cut-off (P@5, P@10, P@15 and P@20) and Mean Average Precision (MAP) were used to measure retrieval effectiveness as it is usually the case in IR. Four word embedding models (CBOW and Skip-gram models for stem-based and root-based text representation) were created offline using word2vec by tuning default parameter values. These models were used for query expansion.

Results

Stopword Identification and Removal

Identification and removal of stopwords are the two preprocessing tasks in many IR systems. In the past, few researches were conducted for creating Amharic stopwords [START_REF] Yeshambel | Evaluation of corpora, resources and tools for Amharic information retrieval[END_REF]. The stopword lists constructed in this research are evaluated using Lemur on Amharic IR test collection. The removal of stopwords has significant impact on the retrieval effectiveness and index size. For example, the retrieval effectiveness of stem-based and root-based text representations with and without stopwords are presented in Table 8. As shown in Table 8, removal of stopwords has positive impact both in case of stem-based and root-based retrievals. For the sake of comparison between stem-based and root-based text retrieval, stem-based stopword list is created based on morpheme statistics (frequency, mean, variance, and entropy) considering the stem-based morphologically annotated corpus such as the case of root-based stopword list. In the rest of the experiments, we removed stopwords from stem-based and root-based corpora using our stem-based and root-based stopword lists. The overall impact of stopwords and the comparison between stem-based and rootbased retrievals are indicated in Figure 2 9 reports the effects of morpho logical analysis on Amharic retrieval effectiveness. We can observe that morphological analysis has an impact on retrieval effectiveness both stem and root-based retrievals are more effective than word-based retrieval. Th root-based retrieval is the best of the three text representations. As expected, the retrieva effectiveness of the three text representations decreases from precision at 5 document (P@5) to precision at 20 documents (P@20) also due to the scarcity of relevant document in the test collection. Root-based retrieval achieves 0.70 for P@20 while stem-based re trieval is 0.53 and word-based retrieval is 0.56.

Figure 3 depicts the overall recall-precision (R-P) curves for the stem-based and root-based text representations. The top line (in blue) is the root-based retrieval effec tiveness, whereas the bottom line (in red) is the stem-based one. In this figure, we could see that the performance of the root-based representation is better than stem-based rep 9 reports the effects of morphological analysis on Amharic retrieval effectiveness. We can observe that morphological analysis has an impact on retrieval effectiveness, both stem and root-based retrievals are more effective than word-based retrieval. The root-based retrieval is the best of the three text representations. As expected, the retrieval effectiveness of the three text representations decreases from precision at 5 documents (P@5) to precision at 20 documents (P@20) also due to the scarcity of relevant documents in the test collection. Root-based retrieval achieves 0.70 for P@20 while stem-based retrieval is 0.53 and word-based retrieval is 0.56.

Query Expansion Using Word Embedding

CBOW and Skip-gram learning algorithms were trained by tuning the default parameter settings into the following same values: vector size (300), min_count [START_REF] Kando | The NTCIR Workshop: The first Evaluation Workshop on Japanese Text Retrieval and Cross-Lingual Information Retrieval[END_REF], iter (400) alpha (0.05) and negative [START_REF] Amsalu | Finite state morphology of Amharic[END_REF]. By experiment, we found that the best performing window size of CBOW (resp. Skip-gram) are 3 (resp.7). The retrieval effectiveness of the proposed Amharic IR system before and after query expansion are presented in Table 10. When considering average results as depicted in the previous section, the root-based text representation retrieves more relevant documents than the stem-based and word-based text representations. This is certainly because the root-based text representation filters out non-relevant documents more accurately than stem-based and word-based. For example, consider the following queries:

1. የአየር ንብረት ብክለት /jəʔəjər nɨbɨrətɨ bɨkɨlətɨ 'air pollution'/ 2. የማዳበሪያ ስርጭት /jəmadabərija sɨrɨtʃ'ɨtɨ 'distribution of fertilizer'/ 3. የኤድስ በሽታ የምርመራ እና የምክር አግልግሎት /jəʔedɨsɨ bəʃɨta jəmɨrɨməra ʔɨna jəmɨkɨrɨ ʔəgɨlɨgɨlotɨ 'AIDS disease examination and consultation service'/

Query Expansion Using Word Embedding

CBOW and Skip-gram learning algorithms were trained by tuning the default parameter settings into the following same values: vector size (300), min_count [START_REF] Kando | The NTCIR Workshop: The first Evaluation Workshop on Japanese Text Retrieval and Cross-Lingual Information Retrieval[END_REF], iter (400), alpha (0.05) and negative [START_REF] Amsalu | Finite state morphology of Amharic[END_REF]. By experiment, we found that the best performing window size of CBOW (resp. Skip-gram) are 3 (resp.7). The retrieval effectiveness of the proposed Amharic IR system before and after query expansion are presented in Table 10. /j and queries. Section 5 presents the evaluation framework of the proposed dhoc retrieval system including the presentation of the resources and corpora, tal setup, and experimental results. In Section 6, we present our conclusion rward further research directions.

Language ic Writing System

ric is the working language of the government of Ethiopia currently having an population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken guage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in mharic is the lingua franca and the most literary language serving as a mestruction in the education system of the country for a long period. Amharic pic alphabet and has 34 base characters along with modifications on the rease characters. The alphabet is conveniently written in a tabular format of mns. The first column represents the basic form with vowel ኧ /ə/ and the rders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following ns: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The as also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic stem is rather most commonly used by Amharic.

ic Morphology ric has complex morphology where many words could be generated through l and derivational processes from other word forms. Many surface forms of be formed from a base form through complex affixation, reduplication, and m interdigitation. Amharic words can be marked for a number of functions. le, a verb can be marked for a combination of person, case, gender, number, ct, and mood. An Amharic word might take up to four prefixes and five sufor example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciproerfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular rker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generan Amharic root or its stems by changing the shape of characters in a stem or ing vowels between root radicals, reduplicating one of the characters of the stem elf, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for ds. However, all variants have a single root representation template. The majors in the language are generated from verbal roots. Nouns, adjectives, and ade derived from verbal roots. The derivation of words from verbal roots usually j r n /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually b /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually r t /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually b /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

2.2.

Amharic Morphology Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually k /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually l t /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually 'air pollution'/ 2.

/j madab rija s six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually r six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually t Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually ' six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually t six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually 'distribution of fertilizer'/ 3.

/j and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually ed seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually s seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually b Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually ta j m seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually r seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually m ra and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually na j m seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually k seven columns. The first column represents the basic form with vowel ኧ /ə/ and the othe six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characte such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its ow punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (prefac colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alph bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rathe most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated throug inflectional and derivational processes from other word forms. Many surface forms o words can be formed from a base form through complex affixation, reduplication, an Semitic stem interdigitation. Amharic words can be marked for a number of function For example, a verb can be marked for a combination of person, case, gender, numbe tense, aspect, and mood. An Amharic word might take up to four prefixes and five su fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔə causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plur object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousand of words can be gener-ated from an Amharic root or its stems by changing the shape characters in a stem or root, inserting vowels between root radicals, reduplicating one the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There a multiple stem templates for verbal words. However, all variants have a single ro representation template. The major-ity of words in the language are generated from verb roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation words from verbal roots usually r seven columns. The first column represents the basic form with vowel ኧ /ə/ and the ot six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized charact such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its o punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (pref colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alp bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rat most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated throu inflectional and derivational processes from other word forms. Many surface forms words can be formed from a base form through complex affixation, reduplication, a Semitic stem interdigitation. Amharic words can be marked for a number of functio For example, a verb can be marked for a combination of person, case, gender, numb tense, aspect, and mood. An Amharic word might take up to four prefixes and five s fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ / causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes ( ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plu object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousan of words can be gener-ated from an Amharic root or its stems by changing the shape characters in a stem or root, inserting vowels between root radicals, reduplicating one the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There multiple stem templates for verbal words. However, all variants have a single r representation template. The major-ity of words in the language are generated from ver roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation words from verbal roots usually and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually g seven columns. The first column represents the basic form with vowel ኧ /ə/ and t six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifica /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized ch such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' colon), etc. It also borrows some punctuation marks such as '?' and '!' from Lati bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated inflectional and derivational processes from other word forms. Many surface f words can be formed from a base form through complex affixation, reduplicat Semitic stem interdigitation. Amharic words can be marked for a number of fu For example, a verb can be marked for a combination of person, case, gender, n tense, aspect, and mood. An Amharic word might take up to four prefixes and fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨn constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffi ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third perso object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Th of words can be gener-ated from an Amharic root or its stems by changing the characters in a stem or root, inserting vowels between root radicals, reduplicatin the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. T multiple stem templates for verbal words. However, all variants have a sin representation template. The major-ity of words in the language are generated from roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The deriv words from verbal roots usually l seven columns. The first column represents the basic form with vowel ኧ /ə/ and six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modific /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized c such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has als punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦ colon), etc. It also borrows some punctuation marks such as '?' and '!' from La bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated inflectional and derivational processes from other word forms. Many surface words can be formed from a base form through complex affixation, reduplica Semitic stem interdigitation. Amharic words can be marked for a number of f For example, a verb can be marked for a combination of person, case, gender tense, aspect, and mood. An Amharic word might take up to four prefixes and fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəw constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suf ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third pers object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). T of words can be gener-ated from an Amharic root or its stems by changing the characters in a stem or root, inserting vowels between root radicals, reduplicati the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. multiple stem templates for verbal words. However, all variants have a si representation template. The major-ity of words in the language are generated fro roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The der words from verbal roots usually g seven columns. The first column represents the basic form with vowel ኧ /ə/ an six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ / /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modi /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has a punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), colon), etc. It also borrows some punctuation marks such as '?' and '!' from L bet. Although Ethiopic alphabet has numeral system, the Arabic numeral syste most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generat inflectional and derivational processes from other word forms. Many surfa words can be formed from a base form through complex affixation, redupli Semitic stem interdigitation. Amharic words can be marked for a number o For example, a verb can be marked for a combination of person, case, gende tense, aspect, and mood. An Amharic word might take up to four prefixes a fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃ constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negatio causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four s ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third pe object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). of words can be gener-ated from an Amharic root or its stems by changing t characters in a stem or root, inserting vowels between root radicals, reduplica the characters of the stem or word itself, and by adding affixes on stems [22 multiple stem templates for verbal words. However, all variants have a representation template. The major-ity of words in the language are generated roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The d words from verbal roots usually lot seven columns. The first column represents the basic form with vowel ኧ /ə six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following m /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labiali such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language ha punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon colon), etc. It also borrows some punctuation marks such as '?' and '!' from bet. Although Ethiopic alphabet has numeral system, the Arabic numeral s most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be gene inflectional and derivational processes from other word forms. Many su words can be formed from a base form through complex affixation, redu Semitic stem interdigitation. Amharic words can be marked for a numbe For example, a verb can be marked for a combination of person, case, ge tense, aspect, and mood. An Amharic word might take up to four prefixe fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkw constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ nega causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and fou ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunctio of words can be gener-ated from an Amharic root or its stems by changin characters in a stem or root, inserting vowels between root radicals, redup the characters of the stem or word itself, and by adding affixes on stems multiple stem templates for verbal words. However, all variants have representation template. The major-ity of words in the language are generat roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. Th words from verbal roots usually 'AIDS disease examination and consultation service'/ 4.

/j d n ses Ethiopic alphabet and has 34 base characters along with modifications on the re-ective base characters. The alphabet is conveniently written in a tabular format of ven columns. The first column represents the basic form with vowel ኧ /ə/ and the other x orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ u/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters ch as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own unctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface lon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-et. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather ost commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through flectional and derivational processes from other word forms. Many surface forms of ords can be formed from a base form through complex affixation, reduplication, and emitic stem interdigitation. Amharic words can be marked for a number of functions. or example, a verb can be marked for a combination of person, case, gender, number, nse, aspect, and mood. An Amharic word might take up to four prefixes and five suf-xes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is nstructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ usative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural bject marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands f words can be gener-ated from an Amharic root or its stems by changing the shape of aracters in a stem or root, inserting vowels between root radicals, reduplicating one of e characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are ultiple stem templates for verbal words. However, all variants have a single root presentation template. The major-ity of words in the language are generated from verbal ots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of ords from verbal roots usually t

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually ' uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually f uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually t 2.1. Amharic Writing System Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually ' fa 'deforestation'/ 5. / ptimal representation of documents and queries considering both root-based sed text representations. t of this paper is organized as follows. Section 2 describes Amharic language phology. Section 3 discusses related work. In Section 4, we present the proaric IR system architecture along with various options to represent Amharic and queries. Section 5 presents the evaluation framework of the proposed oc retrieval system including the presentation of the resources and corpora, l setup, and experimental results. In Section 6, we present our conclusion ard further research directions. Language Writing System ic is the working language of the government of Ethiopia currently having an opulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken uage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in haric is the lingua franca and the most literary language serving as a metruction in the education system of the country for a long period. Amharic ic alphabet and has 34 base characters along with modifications on the ree characters. The alphabet is conveniently written in a tabular format of ns. The first column represents the basic form with vowel ኧ /ə/ and the ers represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following s: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are haracters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The s also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), ፦' (preface colon), etc. It also borrows some punctuation marks such as '?' Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic tem is rather most commonly used by Amharic.

Morphology

ic has complex morphology where many words could be generated through and derivational processes from other word forms. Many surface forms of e formed from a base form through complex affixation, reduplication, and interdigitation. Amharic words can be marked for a number of functions. , a verb can be marked for a combination of person, case, gender, number, t, and mood. An Amharic word might take up to four prefixes and five sufr example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed refixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprorfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular ker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-Amharic root or its stems by changing the shape of characters in a stem or g vowels between root radicals, reduplicating one of the characters of the stem lf, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for s. However, all variants have a single root representation template. The majorin the language are generated from verbal roots. Nouns, adjectives, and adderived from verbal roots. The derivation of words from verbal roots usually l dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually 2. Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually abab 2. Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually b dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually r t' dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually k'at 'Alshebab terrorist attack'/ The aforementioned queries have retrieval precision as shown in Table 11. Test results indicate that precisions at 5 and 10 are higher for root-based representation than for stem-based. The word-based and stem-based methods miss more relevant documents since they could not handle some morphological variations. For example, searching using the stem -/s b r ompiled stopwords list; and (2) to design Amharic IR system by investi-imal representation of documents and queries considering both root-based d text representations. f this paper is organized as follows. Section 2 describes Amharic language ology. Section 3 discusses related work. In Section 4, we present the pro-ic IR system architecture along with various options to represent Amharic d queries. Section 5 presents the evaluation framework of the proposed retrieval system including the presentation of the resources and corpora, setup, and experimental results. In Section 6, we present our conclusion rd further research directions.

nguage riting System

is the working language of the government of Ethiopia currently having an ulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken ge in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in aric is the lingua franca and the most literary language serving as a me-ction in the education system of the country for a long period. Amharic alphabet and has 34 base characters along with modifications on the re-characters. The alphabet is conveniently written in a tabular format of s. The first column represents the basic form with vowel ኧ /ə/ and the other esent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ For example, the base character በ /bə/ has the following modifications: ቡ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters a/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface lso borrows some punctuation marks such as '?' and '!' from Latin alpha-Ethiopic alphabet has numeral system, the Arabic numeral system is rather ly used by Amharic. orphology has complex morphology where many words could be generated through d derivational processes from other word forms. Many surface forms of formed from a base form through complex affixation, reduplication, and nterdigitation. Amharic words can be marked for a number of functions. a verb can be marked for a combination of person, case, gender, number, and mood. An Amharic word might take up to four prefixes and five suf-or example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is om four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands be gener-ated from an Amharic root or its stems by changing the shape of stem or root, inserting vowels between root radicals, reduplicating one of of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root template. The major-ity of words in the language are generated from verbal adjectives, and ad-verbs can be derived from verbal roots. The derivation of rbal roots usually -'break'/ misses documents containing the stem -/s bar corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually -'break'/, -/s ng a standard test collection for IR, morphologically annotated stopwords list; and (2) to design Amharic IR system by investi-esentation of documents and queries considering both root-based resentations. er is organized as follows. Section 2 describes Amharic language ction 3 discusses related work. In Section 4, we present the pro-em architecture along with various options to represent Amharic s. Section 5 presents the evaluation framework of the proposed l system including the presentation of the resources and corpora, d experimental results. In Section 6, we present our conclusion r research directions. tem rking language of the government of Ethiopia currently having an f over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in e lingua franca and the most literary language serving as a me-the education system of the country for a long period. Amharic and has 34 base characters along with modifications on the re-s. The alphabet is conveniently written in a tabular format of t column represents the basic form with vowel ኧ /ə/ and the other difications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ple, the base character በ /bə/ has the following modifications: ቡ e/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters a/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface ws some punctuation marks such as '?' and '!' from Latin alpha-alphabet has numeral system, the Arabic numeral system is rather y Amharic.

lex morphology where many words could be generated through tional processes from other word forms. Many surface forms of rom a base form through complex affixation, reduplication, and tion. Amharic words can be marked for a number of functions. n be marked for a combination of person, case, gender, number, . An Amharic word might take up to four prefixes and five suf-ple, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ -cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural ective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands ated from an Amharic root or its stems by changing the shape of root, inserting vowels between root radicals, reduplicating one of m or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are es for verbal words. However, all variants have a single root . The major-ity of words in the language are generated from verbal , and ad-verbs can be derived from verbal roots. The derivation of usually b r uding a standard test collection for IR, morphologically annotated led stopwords list; and (2) to design Amharic IR system by investi-epresentation of documents and queries considering both root-based representations. paper is organized as follows. Section 2 describes Amharic language . Section 3 discusses related work. In Section 4, we present the pro-ystem architecture along with various options to represent Amharic eries. Section 5 presents the evaluation framework of the proposed eval system including the presentation of the resources and corpora, , and experimental results. In Section 6, we present our conclusion ther research directions. ge System working language of the government of Ethiopia currently having an n of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in is the lingua franca and the most literary language serving as a me-in the education system of the country for a long period. Amharic bet and has 34 base characters along with modifications on the re-cters. The alphabet is conveniently written in a tabular format of first column represents the basic form with vowel ኧ /ə/ and the other modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ xample, the base character በ /bə/ has the following modifications: ቡ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface orrows some punctuation marks such as '?' and '!' from Latin alpha-pic alphabet has numeral system, the Arabic numeral system is rather d by Amharic. logy mplex morphology where many words could be generated through ivational processes from other word forms. Many surface forms of ed from a base form through complex affixation, reduplication, and igitation. Amharic words can be marked for a number of functions. can be marked for a combination of person, case, gender, number, ood. An Amharic word might take up to four prefixes and five suf-xample, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is our prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / lar subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural er-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands er-ated from an Amharic root or its stems by changing the shape of or root, inserting vowels between root radicals, reduplicating one of e stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are lates for verbal words. However, all variants have a single root late. The major-ity of words in the language are generated from verbal ives, and ad-verbs can be derived from verbal roots. The derivation of oots usually -'break'/, and -/s br haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually -'break'/. Despite the stem-based representation could not conflate all variants, it improves retrieval effectiveness to some extent. However, it affects the actual term frequency of some word classes which results in loss of the rank of relevant retrieved documents. For example, the frequency of the three stems and roots of variants in a given document are presented in Table 12. We can see that the frequency of root is higher than the frequency of stem. When looking at the results from which Figure 3 is derived, we found that some relevant documents are retrieved using the root-based representation but not by the stembased one. Some non-relevant documents are retrieved by the stem-based representation but not by the root-based one. For example, for the query ' /j The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through j r Appl. Sci. 2022, 12, x FOR PEER REVIEW limited in scope. The unavailability of full-fledged low-level Amharic NLP tools m difficult to create annotated corpus automatically. Moreover, there is lack of sta reference collection making it a major impediment to the development of Amharic NLP tools. The objective of this research work is: (1) to promote publicly accessib haric resources including a standard test collection for IR, morphologically ann corpora and compiled stopwords list; and (2) to design Amharic IR system by i gating the optimal representation of documents and queries considering both root and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic lan and its morphology. Section 3 discusses related work. In Section 4, we present th posed Amharic IR system architecture along with various options to represent A documents and queries. Section 5 presents the evaluation framework of the pro Amharic adhoc retrieval system including the presentation of the resources and co experimental setup, and experimental results. In Section 6, we present our conc and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently hav estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly s Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spo Ethiopia, Amharic is the lingua franca and the most literary language serving as dium of instruction in the education system of the country for a long period. A uses Ethiopic alphabet and has 34 base characters along with modifications on spective base characters. The alphabet is conveniently written in a tabular for seven columns. The first column represents the basic form with vowel ኧ /ə/ and th six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modificat /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized cha such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also i punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (p colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated th inflectional and derivational processes from other word forms. Many surface fo words can be formed from a base form through complex affixation, reduplicatio Semitic stem interdigitation. Amharic words can be marked for a number of fun For example, a verb can be marked for a combination of person, case, gender, nu tense, aspect, and mood. An Amharic word might take up to four prefixes and fi fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨ constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffix ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Tho of words can be gener-ated from an Amharic root or its stems by changing the sh characters in a stem or root, inserting vowels between root radicals, reduplicating the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. Th multiple stem templates for verbal words. However, all variants have a sing representation template. The major-ity of words in the language are generated from roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The deriva words from verbal roots usually n Appl. Sci. 2022, 12, x FOR PEER REVIEW limited in scope. The unavailability of full-fledged low-level Amharic NLP tools difficult to create annotated corpus automatically. Moreover, there is lack of reference collection making it a major impediment to the development of Amha NLP tools. The objective of this research work is: (1) to promote publicly access haric resources including a standard test collection for IR, morphologically a corpora and compiled stopwords list; and (2) to design Amharic IR system b gating the optimal representation of documents and queries considering both ro and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic and its morphology. Section 3 discusses related work. In Section 4, we presen posed Amharic IR system architecture along with various options to represent documents and queries. Section 5 presents the evaluation framework of the Amharic adhoc retrieval system including the presentation of the resources and experimental setup, and experimental results. In Section 6, we present our co and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently h estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonl Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are s Ethiopia, Amharic is the lingua franca and the most literary language serving dium of instruction in the education system of the country for a long period. uses Ethiopic alphabet and has 34 base characters along with modifications o spective base characters. The alphabet is conveniently written in a tabular f seven columns. The first column represents the basic form with vowel ኧ /ə/ and six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modific /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized c such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has als punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦ colon), etc. It also borrows some punctuation marks such as '?' and '!' from Lat bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated inflectional and derivational processes from other word forms. Many surface words can be formed from a base form through complex affixation, reduplica Semitic stem interdigitation. Amharic words can be marked for a number of f For example, a verb can be marked for a combination of person, case, gender, tense, aspect, and mood. An Amharic word might take up to four prefixes and fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəw constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suf ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third pers object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). T of words can be gener-ated from an Amharic root or its stems by changing the characters in a stem or root, inserting vowels between root radicals, reduplicati the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. multiple stem templates for verbal words. However, all variants have a si representation template. The major-ity of words in the language are generated fro roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The der words from verbal roots usually b Appl. Sci. 2022, 12, x FOR PEER REVIEW limited in scope. The unavailability of full-fledged low-level Amharic NLP too difficult to create annotated corpus automatically. Moreover, there is lack o reference collection making it a major impediment to the development of Amh NLP tools. The objective of this research work is: (1) to promote publicly acce haric resources including a standard test collection for IR, morphologically corpora and compiled stopwords list; and (2) to design Amharic IR system gating the optimal representation of documents and queries considering both and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amhar and its morphology. Section 3 discusses related work. In Section 4, we prese posed Amharic IR system architecture along with various options to represe documents and queries. Section 5 presents the evaluation framework of the Amharic adhoc retrieval system including the presentation of the resources an experimental setup, and experimental results. In Section 6, we present our and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commo Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages ar Ethiopia, Amharic is the lingua franca and the most literary language servin dium of instruction in the education system of the country for a long period uses Ethiopic alphabet and has 34 base characters along with modifications spective base characters. The alphabet is conveniently written in a tabular seven columns. The first column represents the basic form with vowel ኧ /ə/ an six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ / /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modi /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has a punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), ' colon), etc. It also borrows some punctuation marks such as '?' and '!' from L bet. Although Ethiopic alphabet has numeral system, the Arabic numeral syste most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generat inflectional and derivational processes from other word forms. Many surfac words can be formed from a base form through complex affixation, redupli Semitic stem interdigitation. Amharic words can be marked for a number o For example, a verb can be marked for a combination of person, case, gende tense, aspect, and mood. An Amharic word might take up to four prefixes an fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃə constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four s ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third pe object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). of words can be gener-ated from an Amharic root or its stems by changing th characters in a stem or root, inserting vowels between root radicals, reduplica the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF] multiple stem templates for verbal words. However, all variants have a representation template. The major-ity of words in the language are generated f roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The d words from verbal roots usually r t The rest of this paper is organized as follows. Section 2 describes Am and its morphology. Section 3 discusses related work. In Section 4, we pr posed Amharic IR system architecture along with various options to repr documents and queries. Section 5 presents the evaluation framework of Amharic adhoc retrieval system including the presentation of the resource experimental setup, and experimental results. In Section 6, we present o and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia curre estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most com Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages Ethiopia, Amharic is the lingua franca and the most literary language se dium of instruction in the education system of the country for a long pe uses Ethiopic alphabet and has 34 base characters along with modificati spective base characters. The alphabet is conveniently written in a tab seven columns. The first column represents the basic form with vowel ኧ /ə six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following m /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labiali such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language ha punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon colon), etc. It also borrows some punctuation marks such as '?' and '!' from bet. Although Ethiopic alphabet has numeral system, the Arabic numeral s most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be gene inflectional and derivational processes from other word forms. Many su words can be formed from a base form through complex affixation, redu Semitic stem interdigitation. Amharic words can be marked for a numbe For example, a verb can be marked for a combination of person, case, ge tense, aspect, and mood. An Amharic word might take up to four prefixe fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkw constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ nega causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and fou ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunctio of words can be gener-ated from an Amharic root or its stems by changin characters in a stem or root, inserting vowels between root radicals, redup the characters of the stem or word itself, and by adding affixes on stems multiple stem templates for verbal words. However, all variants have representation template. The major-ity of words in the language are generat roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. Th words from verbal roots usually b 3 of 29 availability of full-fledged low-level Amharic NLP tools makes it ated corpus automatically. Moreover, there is lack of standard ing it a major impediment to the development of Amharic IR and of this research work is: (1) to promote publicly accessible Am-g a standard test collection for IR, morphologically annotated topwords list; and (2) to design Amharic IR system by investi-sentation of documents and queries considering both root-based esentations. er is organized as follows. Section 2 describes Amharic language tion 3 discusses related work. In Section 4, we present the pro-m architecture along with various options to represent Amharic . Section 5 presents the evaluation framework of the proposed system including the presentation of the resources and corpora, experimental results. In Section 6, we present our conclusion research directions. em ing language of the government of Ethiopia currently having an over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in lingua franca and the most literary language serving as a me-he education system of the country for a long period. Amharic nd has 34 base characters along with modifications on the re-. The alphabet is conveniently written in a tabular format of column represents the basic form with vowel ኧ /ə/ and the other ifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ple, the base character በ /bə/ has the following modifications: ቡ /, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters a/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface s some punctuation marks such as '?' and '!' from Latin alpha-lphabet has numeral system, the Arabic numeral system is rather Amharic. ex morphology where many words could be generated through onal processes from other word forms. Many surface forms of om a base form through complex affixation, reduplication, and tion. Amharic words can be marked for a number of functions. be marked for a combination of person, case, gender, number, . An Amharic word might take up to four prefixes and five suf-ple, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ubject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural ctive verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands ted from an Amharic root or its stems by changing the shape of oot, inserting vowels between root radicals, reduplicating one of or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are s for verbal words. However, all variants have a single root The major-ity of words in the language are generated from verbal and ad-verbs can be derived from verbal roots. The derivation of k 3 of 29 navailability of full-fledged low-level Amharic NLP tools makes it otated corpus automatically. Moreover, there is lack of standard king it a major impediment to the development of Amharic IR and e of this research work is: (1) to promote publicly accessible Am-ing a standard test collection for IR, morphologically annotated stopwords list; and (2) to design Amharic IR system by investi-resentation of documents and queries considering both root-based presentations. per is organized as follows. Section 2 describes Amharic language ection 3 discusses related work. In Section 4, we present the pro-tem architecture along with various options to represent Amharic s. Section 5 presents the evaluation framework of the proposed l system including the presentation of the resources and corpora, d experimental results. In Section 6, we present our conclusion r research directions. stem rking language of the government of Ethiopia currently having an of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken e world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in he lingua franca and the most literary language serving as a me-the education system of the country for a long period. Amharic t and has 34 base characters along with modifications on the re-rs. The alphabet is conveniently written in a tabular format of st column represents the basic form with vowel ኧ /ə/ and the other odifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ple, the base character በ /bə/ has the following modifications: ቡ e/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters wa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface ows some punctuation marks such as '?' and '!' from Latin alpha-alphabet has numeral system, the Arabic numeral system is rather y Amharic. y plex morphology where many words could be generated through tional processes from other word forms. Many surface forms of from a base form through complex affixation, reduplication, and tation. Amharic words can be marked for a number of functions. n be marked for a combination of person, case, gender, number, d. An Amharic word might take up to four prefixes and five suf-ple, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is r prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ o-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands -ated from an Amharic root or its stems by changing the shape of root, inserting vowels between root radicals, reduplicating one of em or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are tes for verbal words. However, all variants have a single root e. The major-ity of words in the language are generated from verbal s, and ad-verbs can be derived from verbal roots. The derivation of l t paper is organized as follows. Section 2 describes Amharic language . Section 3 discusses related work. In Section 4, we present the pro-system architecture along with various options to represent Amharic eries. Section 5 presents the evaluation framework of the proposed eval system including the presentation of the resources and corpora, , and experimental results. In Section 6, we present our conclusion rther research directions.

ge System working language of the government of Ethiopia currently having an on of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in is the lingua franca and the most literary language serving as a me-in the education system of the country for a long period. Amharic bet and has 34 base characters along with modifications on the re-cters. The alphabet is conveniently written in a tabular format of first column represents the basic form with vowel ኧ /ə/ and the other t modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ xample, the base character በ /bə/ has the following modifications: ቡ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface orrows some punctuation marks such as '?' and '!' from Latin alpha-pic alphabet has numeral system, the Arabic numeral system is rather ed by Amharic. logy omplex morphology where many words could be generated through rivational processes from other word forms. Many surface forms of ed from a base form through complex affixation, reduplication, and igitation. Amharic words can be marked for a number of functions. b can be marked for a combination of person, case, gender, number, ood. An Amharic word might take up to four prefixes and five suf-xample, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is our prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural er-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands ner-ated from an Amharic root or its stems by changing the shape of or root, inserting vowels between root radicals, reduplicating one of e stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are plates for verbal words. However, all variants have a single root late. The major-ity of words in the language are generated from verbal ives, and ad-verbs can be derived from verbal roots. The derivation of 'air pollution'/' the root-based retrieval returns 10 relevant documents in the top 10, while the stem-based text representation returns only 3 relevant documents in the top 10. The reasons are the three strong sides of root over stem as described in what follows.

i.

Root can conflate all morphologically variants to one common root. For example, the stems of variants /s b r /, /s

. 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of b r l. Sci. 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of /, /s The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of b Appl. Sci. 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of rat Appl. Sci. 2022, 12, x FOR PEER REVIEW 3 of 29 limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Am-haric resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investi-gating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the pro-posed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a me-dium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the re-spective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suf-fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of /, / The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns.

The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' sab r /, /s bara/, / ric is the working language of the government of Ethiopia currently having an population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken guage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in mharic is the lingua franca and the most literary language serving as a mestruction in the education system of the country for a long period. Amharic pic alphabet and has 34 base characters along with modifications on the rease characters. The alphabet is conveniently written in a tabular format of mns. The first column represents the basic form with vowel ኧ /ə/ and the rders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following ons: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The as also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic ystem is rather most commonly used by Amharic.

ic Morphology ric has complex morphology where many words could be generated through l and derivational processes from other word forms. Many surface forms of be formed from a base form through complex affixation, reduplication, and m interdigitation. Amharic words can be marked for a number of functions. le, a verb can be marked for a combination of person, case, gender, number, ct, and mood. An Amharic word might take up to four prefixes and five suf-For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciproerfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular rker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generan Amharic root or its stems by changing the shape of characters in a stem or ing vowels between root radicals, reduplicating one of the characters of the stem self, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for ds. However, all variants have a single root representation template. The majors in the language are generated from verbal roots. Nouns, adjectives, and ade derived from verbal roots. The derivation of words from verbal roots usually sab 2.2. Amharic Morphology Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually rat 2.2.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually /, /t s b 2.2.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually ro/ are -/s b r

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually -/, -/s

Amharic Morphology

Amharic has complex morphology where many words could be generated throu inflectional and derivational processes from other word forms. Many surface forms words can be formed from a base form through complex affixation, reduplication, a Semitic stem interdigitation. Amharic words can be marked for a number of functio For example, a verb can be marked for a combination of person, case, gender, numb tense, aspect, and mood. An Amharic word might take up to four prefixes and five s fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ / causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes ( ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plu object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousan of words can be gener-ated from an Amharic root or its stems by changing the shape characters in a stem or root, inserting vowels between root radicals, reduplicating one the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There multiple stem templates for verbal words. However, all variants have a single r representation template. The major-ity of words in the language are generated from ver roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation words from verbal roots usually b r

Amharic Morphology

Amharic has complex morphology where many words could be generated th inflectional and derivational processes from other word forms. Many surface fo words can be formed from a base form through complex affixation, reduplicatio Semitic stem interdigitation. Amharic words can be marked for a number of fun For example, a verb can be marked for a combination of person, case, gender, n tense, aspect, and mood. An Amharic word might take up to four prefixes and fi fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨ constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffix ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Tho of words can be gener-ated from an Amharic root or its stems by changing the sh characters in a stem or root, inserting vowels between root radicals, reduplicating the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. Th multiple stem templates for verbal words. However, all variants have a sing representation template. The major-ity of words in the language are generated from roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The deriva words from verbal roots usually -/, -/s hology complex morphology where many words could be generated through erivational processes from other word forms. Many surface forms of ed from a base form through complex affixation, reduplication, and rdigitation. Amharic words can be marked for a number of functions. rb can be marked for a combination of person, case, gender, number, mood. An Amharic word might take up to four prefixes and five sufexample, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ cipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / gular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands ener-ated from an Amharic root or its stems by changing the shape of m or root, inserting vowels between root radicals, reduplicating one of he stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are plates for verbal words. However, all variants have a single root plate. The major-ity of words in the language are generated from verbal ctives, and ad-verbs can be derived from verbal roots. The derivation of l roots usually b phology s complex morphology where many words could be generated through derivational processes from other word forms. Many surface forms of rmed from a base form through complex affixation, reduplication, and erdigitation. Amharic words can be marked for a number of functions. verb can be marked for a combination of person, case, gender, number, d mood. An Amharic word might take up to four prefixes and five sufexample, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is m four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ingular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural r per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands gener-ated from an Amharic root or its stems by changing the shape of tem or root, inserting vowels between root radicals, reduplicating one of f the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are emplates for verbal words. However, all variants have a single root mplate. The major-ity of words in the language are generated from verbal jectives, and ad-verbs can be derived from verbal roots. The derivation of al roots usually r orphology has complex morphology where many words could be generated through d derivational processes from other word forms. Many surface forms of formed from a base form through complex affixation, reduplication, and nterdigitation. Amharic words can be marked for a number of functions.

verb can be marked for a combination of person, case, gender, number, nd mood. An Amharic word might take up to four prefixes and five sufor example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is om four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands e gener-ated from an Amharic root or its stems by changing the shape of stem or root, inserting vowels between root radicals, reduplicating one of of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root template. The major-ity of words in the language are generated from verbal djectives, and ad-verbs can be derived from verbal roots. The derivation of rbal roots usually -/, -/sabar

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually -/, -/s bar

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually -/, -/sab

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually r 2.2.

Amharic Morphology Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually -/, and /s b r

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually -/, respectively. This creates vocabulary mismatch. Many words have similar cases in Amharic. However, all variants have one common root --/s-b-r/. Therefore, the root-based representation increases the term frequency which usually leads to better retrieval result and rank. ii.

Root does not conflate semantically unrelated words to a common form. However, this is not the case for the stem-based representation which may conflate semantically unrelated words to a common form. For example, /g d l /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually / is the stem of the verb /g d l 'he killed'/ and the noun /g d lot

Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually 'cracks'/. The verb /sig d s. The first column represents the basic form with vowel ኧ /ə/ and the other resent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ For example, the base character በ /bə/ has the following modifications: ቡ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters a/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface also borrows some punctuation marks such as '?' and '!' from Latin alpha-Ethiopic alphabet has numeral system, the Arabic numeral system is rather ly used by Amharic. orphology has complex morphology where many words could be generated through d derivational processes from other word forms. Many surface forms of formed from a base form through complex affixation, reduplication, and interdigitation. Amharic words can be marked for a number of functions. a verb can be marked for a combination of person, case, gender, number, and mood. An Amharic word might take up to four prefixes and five sufor example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is rom four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands be gener-ated from an Amharic root or its stems by changing the shape of stem or root, inserting vowels between root radicals, reduplicating one of of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root template. The major-ity of words in the language are generated from verbal adjectives, and ad-verbs can be derived from verbal roots. The derivation of rbal roots usually l ns. The first column represents the basic form with vowel ኧ /ə/ and the other present modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /. For example, the base character በ /bə/ has the following modifications: ቡ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters wa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own s such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface t also borrows some punctuation marks such as '?' and '!' from Latin alphah Ethiopic alphabet has numeral system, the Arabic numeral system is rather nly used by Amharic.

Morphology

c has complex morphology where many words could be generated through nd derivational processes from other word forms. Many surface forms of e formed from a base form through complex affixation, reduplication, and interdigitation. Amharic words can be marked for a number of functions. , a verb can be marked for a combination of person, case, gender, number, , and mood. An Amharic word might take up to four prefixes and five suf-For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / n singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural r for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands be gener-ated from an Amharic root or its stems by changing the shape of a stem or root, inserting vowels between root radicals, reduplicating one of s of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are m templates for verbal words. However, all variants have a single root n template. The major-ity of words in the language are generated from verbal , adjectives, and ad-verbs can be derived from verbal roots. The derivation of erbal roots usually 'as he kills'/ and the noun /g d seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually l seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually 'contending'/ have the same stem -/g d haracters. The alphabet is conveniently written in a tabular format of The first column represents the basic form with vowel ኧ /ə/ and the other sent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ or example, the base character በ /bə/ has the following modifications: ቡ a/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ch as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface so borrows some punctuation marks such as '?' and '!' from Latin alphathiopic alphabet has numeral system, the Arabic numeral system is rather used by Amharic. rphology as complex morphology where many words could be generated through derivational processes from other word forms. Many surface forms of ormed from a base form through complex affixation, reduplication, and terdigitation. Amharic words can be marked for a number of functions. verb can be marked for a combination of person, case, gender, number, nd mood. An Amharic word might take up to four prefixes and five sufr example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is m four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ingular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural or per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands e gener-ated from an Amharic root or its stems by changing the shape of stem or root, inserting vowels between root radicals, reduplicating one of f the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root emplate. The major-ity of words in the language are generated from verbal djectives, and ad-verbs can be derived from verbal roots. The derivation of bal roots usually l characters. The alphabet is conveniently written in a tabular format of s. The first column represents the basic form with vowel ኧ /ə/ and the other esent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ For example, the base character በ /bə/ has the following modifications: ቡ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters a/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface lso borrows some punctuation marks such as '?' and '!' from Latin alpha-Ethiopic alphabet has numeral system, the Arabic numeral system is rather ly used by Amharic. orphology has complex morphology where many words could be generated through d derivational processes from other word forms. Many surface forms of formed from a base form through complex affixation, reduplication, and nterdigitation. Amharic words can be marked for a number of functions. a verb can be marked for a combination of person, case, gender, number, and mood. An Amharic word might take up to four prefixes and five sufor example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is om four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands be gener-ated from an Amharic root or its stems by changing the shape of stem or root, inserting vowels between root radicals, reduplicating one of of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root template. The major-ity of words in the language are generated from verbal adjectives, and ad-verbs can be derived from verbal roots. The derivation of rbal roots usually -/. This leads to retrieval of non-relevant documents when using stems, which decreases precision.

iii. The retrieval results of the stem-based representation depend on the query word variants, while the root-based representation does not. The root-based representation performs equally for all the variants of the query terms. However, the stem-based representation returns different results in different ranks. Users would certainly construct the same information need using different queries, using different word variants. However, in Amharic, query terms of word variants might not be similar after stemming. For example, a query 'the causes of air pollution' could be constructed as ' /j in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it lt to create annotated corpus automatically. Moreover, there is lack of standard ce collection making it a major impediment to the development of Amharic IR and ools. The objective of this research work is: (1) to promote publicly accessible Amresources including a standard test collection for IR, morphologically annotated a and compiled stopwords list; and (2) to design Amharic IR system by investithe optimal representation of documents and queries considering both root-based em-based text representations. he rest of this paper is organized as follows. Section 2 describes Amharic language s morphology. Section 3 discusses related work. In Section 4, we present the pro-Amharic IR system architecture along with various options to represent Amharic ents and queries. Section 5 presents the evaluation framework of the proposed ric adhoc retrieval system including the presentation of the resources and corpora, mental setup, and experimental results. In Section 6, we present our conclusion t forward further research directions.

haric Language haric Writing System mharic is the working language of the government of Ethiopia currently having an ted population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken c language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in ia, Amharic is the lingua franca and the most literary language serving as a meof instruction in the education system of the country for a long period. Amharic thiopic alphabet and has 34 base characters along with modifications on the ree base characters. The alphabet is conveniently written in a tabular format of columns. The first column represents the basic form with vowel ኧ /ə/ and the six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following ications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are zed characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The ge has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), lon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic al system is rather most commonly used by Amharic. haric Morphology mharic has complex morphology where many words could be generated through ional and derivational processes from other word forms. Many surface forms of can be formed from a base form through complex affixation, reduplication, and c stem interdigitation. Amharic words can be marked for a number of functions. ample, a verb can be marked for a combination of person, case, gender, number, aspect, and mood. An Amharic word might take up to four prefixes and five suf-18]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed our prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprohe perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular t marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perverb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generom an Amharic root or its stems by changing the shape of characters in a stem or serting vowels between root radicals, reduplicating one of the characters of the stem rd itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for words. However, all variants have a single root representation template. The majorwords in the language are generated from verbal roots. Nouns, adjectives, and adcan be derived from verbal roots. The derivation of words from verbal roots usually j r

2.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually n 2. Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually b 2. Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually r t

2.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually b 2. Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually k 2. Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually l t

2.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually m n

2.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually s 2. Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually limited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it difficult to create annotated corpus automatically. Moreover, there is lack of standard reference collection making it a major impediment to the development of Amharic IR and NLP tools. The objective of this research work is: (1) to promote publicly accessible Amharic resources including a standard test collection for IR, morphologically annotated corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language 2.1. Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciprocal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perfective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The majority of words in the language are generated from verbal roots. Nouns, adjectives, and adverbs can be derived from verbal roots. The derivation of words from verbal roots usually ewot gating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually

2.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually /' or ' /j 3 of 29 ailability of full-fledged low-level Amharic NLP tools makes it d corpus automatically. Moreover, there is lack of standard it a major impediment to the development of Amharic IR and f this research work is: (1) to promote publicly accessible Ama standard test collection for IR, morphologically annotated words list; and (2) to design Amharic IR system by investitation of documents and queries considering both root-based entations. is organized as follows. Section 2 describes Amharic language n 3 discusses related work. In Section 4, we present the proarchitecture along with various options to represent Amharic ection 5 presents the evaluation framework of the proposed stem including the presentation of the resources and corpora, xperimental results. In Section 6, we present our conclusion search directions. g language of the government of Ethiopia currently having an ver 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken rld after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in ngua franca and the most literary language serving as a meeducation system of the country for a long period. Amharic has 34 base characters along with modifications on the rehe alphabet is conveniently written in a tabular format of column represents the basic form with vowel ኧ /ə/ and the modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / /. For example, the base character በ /bə/ has the following bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The unctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), on), etc. It also borrows some punctuation marks such as '?' t. Although Ethiopic alphabet has numeral system, the Arabic ost commonly used by Amharic.

morphology where many words could be generated through al processes from other word forms. Many surface forms of a base form through complex affixation, reduplication, and n. Amharic words can be marked for a number of functions. e marked for a combination of person, case, gender, number, n Amharic word might take up to four prefixes and five sufword ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed eposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-ሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular verb/, አቸው /ʔətʃəwɨ third person plural object marker for perve/, and ና /na conjunction/). Thousands of words can be generor its stems by changing the shape of characters in a stem or een root radicals, reduplicating one of the characters of the stem ng affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for variants have a single root representation template. The majore are generated from verbal roots. Nouns, adjectives, and adverbal roots. The derivation of words from verbal roots usually j r ard further research directions.

anguage riting System

is the working language of the government of Ethiopia currently having an pulation of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken age in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in haric is the lingua franca and the most literary language serving as a meuction in the education system of the country for a long period. Amharic alphabet and has 34 base characters along with modifications on the recharacters. The alphabet is conveniently written in a tabular format of s. The first column represents the basic form with vowel ኧ /ə/ and the other resent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ . For example, the base character በ /bə/ has the following modifications: ቡ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters a/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface also borrows some punctuation marks such as '?' and '!' from Latin alpha-Ethiopic alphabet has numeral system, the Arabic numeral system is rather nly used by Amharic. orphology has complex morphology where many words could be generated through nd derivational processes from other word forms. Many surface forms of formed from a base form through complex affixation, reduplication, and interdigitation. Amharic words can be marked for a number of functions. a verb can be marked for a combination of person, case, gender, number, and mood. An Amharic word might take up to four prefixes and five suf-For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is rom four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural r for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands be gener-ated from an Amharic root or its stems by changing the shape of a stem or root, inserting vowels between root radicals, reduplicating one of of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are templates for verbal words. However, all variants have a single root template. The major-ity of words in the language are generated from verbal adjectives, and ad-verbs can be derived from verbal roots. The derivation of erbal roots usually n rward further research directions.

Language ic Writing System

ric is the working language of the government of Ethiopia currently having an population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken guage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in mharic is the lingua franca and the most literary language serving as a mestruction in the education system of the country for a long period. Amharic pic alphabet and has 34 base characters along with modifications on the rease characters. The alphabet is conveniently written in a tabular format of mns. The first column represents the basic form with vowel ኧ /ə/ and the other represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ , ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ns such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface It also borrows some punctuation marks such as '?' and '!' from Latin alphagh Ethiopic alphabet has numeral system, the Arabic numeral system is rather only used by Amharic.

ic Morphology ric has complex morphology where many words could be generated through l and derivational processes from other word forms. Many surface forms of be formed from a base form through complex affixation, reduplication, and m interdigitation. Amharic words can be marked for a number of functions. le, a verb can be marked for a combination of person, case, gender, number, ct, and mood. An Amharic word might take up to four prefixes and five suf-. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / son singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural ker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands an be gener-ated from an Amharic root or its stems by changing the shape of in a stem or root, inserting vowels between root radicals, reduplicating one of ers of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are tem templates for verbal words. However, all variants have a single root ion template. The major-ity of words in the language are generated from verbal ns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of verbal roots usually b orward further research directions.

haric is the working language of the government of Ethiopia currently having an population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken anguage in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Amharic is the lingua franca and the most literary language serving as a meinstruction in the education system of the country for a long period. Amharic iopic alphabet and has 34 base characters along with modifications on the rebase characters. The alphabet is conveniently written in a tabular format of lumns. The first column represents the basic form with vowel ኧ /ə/ and the other s represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ i/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own ions such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface c. It also borrows some punctuation marks such as '?' and '!' from Latin alphaough Ethiopic alphabet has numeral system, the Arabic numeral system is rather monly used by Amharic.

ric Morphology haric has complex morphology where many words could be generated through al and derivational processes from other word forms. Many surface forms of n be formed from a base form through complex affixation, reduplication, and tem interdigitation. Amharic words can be marked for a number of functions. ple, a verb can be marked for a combination of person, case, gender, number, ect, and mood. An Amharic word might take up to four prefixes and five suf-8]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ /, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / erson singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural arker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands can be gener-ated from an Amharic root or its stems by changing the shape of s in a stem or root, inserting vowels between root radicals, reduplicating one of cters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are stem templates for verbal words. However, all variants have a single root ation template. The major-ity of words in the language are generated from verbal uns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of m verbal roots usually r t ut forward further research directions.

mharic is the working language of the government of Ethiopia currently having an ated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken ic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in pia, Amharic is the lingua franca and the most literary language serving as a meof instruction in the education system of the country for a long period. Amharic Ethiopic alphabet and has 34 base characters along with modifications on the reive base characters. The alphabet is conveniently written in a tabular format of columns. The first column represents the basic form with vowel ኧ /ə/ and the other ders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ d ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own uations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface ), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphalthough Ethiopic alphabet has numeral system, the Arabic numeral system is rather commonly used by Amharic.

mharic Morphology mharic has complex morphology where many words could be generated through tional and derivational processes from other word forms. Many surface forms of s can be formed from a base form through complex affixation, reduplication, and ic stem interdigitation. Amharic words can be marked for a number of functions. xample, a verb can be marked for a combination of person, case, gender, number, , aspect, and mood. An Amharic word might take up to four prefixes and five suf- [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ tive/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / st person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural t marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands rds can be gener-ated from an Amharic root or its stems by changing the shape of cters in a stem or root, inserting vowels between root radicals, reduplicating one of aracters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are ple stem templates for verbal words. However, all variants have a single root sentation template. The major-ity of words in the language are generated from verbal Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of s from verbal roots usually b kaj and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually m n and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually s and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually W 3 of 29 mited in scope. The unavailability of full-fledged low-level Amharic NLP tools makes it ifficult to create annotated corpus automatically. Moreover, there is lack of standard eference collection making it a major impediment to the development of Amharic IR and LP tools. The objective of this research work is: (1) to promote publicly accessible Amaric resources including a standard test collection for IR, morphologically annotated orpora and compiled stopwords list; and (2) to design Amharic IR system by investiating the optimal representation of documents and queries considering both root-based nd stem-based text representations. The rest of this paper is organized as follows. Section 2 describes Amharic language nd its morphology. Section 3 discusses related work. In Section 4, we present the proosed Amharic IR system architecture along with various options to represent Amharic ocuments and queries. Section 5 presents the evaluation framework of the proposed mharic adhoc retrieval system including the presentation of the resources and corpora, xperimental setup, and experimental results. In Section 6, we present our conclusion nd put forward further research directions.

. Amharic Language .1. Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an stimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken emitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in thiopia, Amharic is the lingua franca and the most literary language serving as a meium of instruction in the education system of the country for a long period. Amharic ses Ethiopic alphabet and has 34 base characters along with modifications on the repective base characters. The alphabet is conveniently written in a tabular format of even columns. The first column represents the basic form with vowel ኧ /ə/ and the ther six orders represent modifications with vowels in the order of ኡ / ʔ u/, ኢ /ʔi/, ኣ / a/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following odifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are bialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The nguage has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), ' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' nd '!' from Latin alpha-bet. Although Ethiopic alphabet has numeral system, the Arabic umeral system is rather most commonly used by Amharic.

.

Amharic Morphology

Amharic has complex morphology where many words could be generated through flectional and derivational processes from other word forms. Many surface forms of ords can be formed from a base form through complex affixation, reduplication, and emitic stem interdigitation. Amharic words can be marked for a number of functions. or example, a verb can be marked for a combination of person, case, gender, number, ense, aspect, and mood. An Amharic word might take up to four prefixes and five sufixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed rom four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə reciproal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular ubject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for perective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be generted from an Amharic root or its stems by changing the shape of characters in a stem or oot, inserting vowels between root radicals, reduplicating one of the characters of the stem r word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for erbal words. However, all variants have a single root representation template. The majory of words in the language are generated from verbal roots. Nouns, adjectives, and aderbs can be derived from verbal roots. The derivation of words from verbal roots usually ewot corpora and compiled stopwords list; and (2) to design Amharic IR system by investigating the optimal representation of documents and queries considering both root-based and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwat ʃ əwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəlɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ /ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are multiple stem templates for verbal words. However, all variants have a single root representation template. The major-ity of words in the language are generated from verbal roots. Nouns, adjectives, and ad-verbs can be derived from verbal roots. The derivation of words from verbal roots usually /'. In stem-based representation, the two queries have { , , , } and { , , , } query terms, respectively, in which case the system retrieves different results. In the case of root-based representation, the two queries have the same set of query terms { , , --, }, which guarantees the same retrieval result.

Several queries may be formulated by users with variants of words. To investigate the effect of stems of variants of words in queries on the overall Amharic IR, we created an alternative form of each query in our test collection and made the comparison between the two options. The two stem-based forms represent variants of words in users' queries. All possible options of a query formulated from variants of words have the same root-based representation though they might have more than one stem representation. As depicted in Figure 4, the two query options in stem-based representation performed differently on the same test collection, but performed equally in case of root-based representation. The top curve (in green) is the root-based retrieval whereas the remaining two are the stem-based retrievals. The stem-based retrieval curves might be even changed if our queries in the topic set are constructed just by changing only variants of one or more words in each query.

Comparison of Amharic IR before and after Query Expansion

Stem-based and root-based retrieval effectiveness before and after query expansion are investigated on the same corpus using the same retrieval model that is LM. Figure 5 depicted the overall retrieval effectiveness of Amharic IR system with and without query expansion on the same test collection and retrieval mode. The red, blue, aqua, purple, yellow and green colors represent root-based retrieval without query expansion, stembased retrieval without query expansion, root-based retrieval after query expansion using Skip-gram, root-based retrieval after query expansion using CBOW, stem-based retrieval after query expansion using CBOW, and stem-based retrieval after query expansion using Skip-gram algorithm. As shown in Table 10 and Figure 5, Amharic IR retrieval after query expansion is less than conventional retrieval. Some expanded terms of an initial query term are related syntactically rather than semantically. These syntactical related terms affect the retrieval effectiveness of Amharic IR. For example, the city name /bah The rest of this paper is organized as follows. Section 2 describes Amharic la and its morphology. Section 3 discusses related work. In Section 4, we present posed Amharic IR system architecture along with various options to represent A documents and queries. Section 5 presents the evaluation framework of the p Amharic adhoc retrieval system including the presentation of the resources and experimental setup, and experimental results. In Section 6, we present our con and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently ha estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are sp Ethiopia, Amharic is the lingua franca and the most literary language serving a dium of instruction in the education system of the country for a long period. A uses Ethiopic alphabet and has 34 base characters along with modifications on spective base characters. The alphabet is conveniently written in a tabular fo seven columns. The first column represents the basic form with vowel ኧ /ə/ and t six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifica /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized ch such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' colon), etc. It also borrows some punctuation marks such as '?' and '!' from Lati bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated inflectional and derivational processes from other word forms. Many surface f words can be formed from a base form through complex affixation, reduplicati Semitic stem interdigitation. Amharic words can be marked for a number of fu For example, a verb can be marked for a combination of person, case, gender, n tense, aspect, and mood. An Amharic word might take up to four prefixes and fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨn constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffi ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third perso object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Th of words can be gener-ated from an Amharic root or its stems by changing the s characters in a stem or root, inserting vowels between root radicals, reduplicatin the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. T multiple stem templates for verbal words. However, all variants have a sin representation template. The major-ity of words in the language are generated from r Appl. Sci. 2022, 12, x FOR PEER REVIEW limited in scope. The unavailability of full-fledged low-level Amharic NLP tool difficult to create annotated corpus automatically. Moreover, there is lack of reference collection making it a major impediment to the development of Amha NLP tools. The objective of this research work is: (1) to promote publicly acces haric resources including a standard test collection for IR, morphologically a corpora and compiled stopwords list; and (2) to design Amharic IR system b gating the optimal representation of documents and queries considering both r and stem-based text representations.

The rest of this paper is organized as follows. Section 2 describes Amharic and its morphology. Section 3 discusses related work. In Section 4, we presen posed Amharic IR system architecture along with various options to represent documents and queries. Section 5 presents the evaluation framework of the Amharic adhoc retrieval system including the presentation of the resources and experimental setup, and experimental results. In Section 6, we present our c and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most common Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are Ethiopia, Amharic is the lingua franca and the most literary language serving dium of instruction in the education system of the country for a long period. uses Ethiopic alphabet and has 34 base characters along with modifications o spective base characters. The alphabet is conveniently written in a tabular seven columns. The first column represents the basic form with vowel ኧ /ə/ and six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifi /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized c such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has als punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦ colon), etc. It also borrows some punctuation marks such as '?' and '!' from La bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated inflectional and derivational processes from other word forms. Many surface words can be formed from a base form through complex affixation, reduplica Semitic stem interdigitation. Amharic words can be marked for a number of For example, a verb can be marked for a combination of person, case, gender tense, aspect, and mood. An Amharic word might take up to four prefixes and fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəw constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suf ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third pers object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). T of words can be gener-ated from an Amharic root or its stems by changing the characters in a stem or root, inserting vowels between root radicals, reduplicati the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. multiple stem templates for verbal words. However, all variants have a si representation template. The major-ity of words in the language are generated fr The rest of this paper is organized as follows. Section 2 describes Amh and its morphology. Section 3 discusses related work. In Section 4, we pre posed Amharic IR system architecture along with various options to repre documents and queries. Section 5 presents the evaluation framework of Amharic adhoc retrieval system including the presentation of the resources experimental setup, and experimental results. In Section 6, we present o and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia curren estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most comm Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages Ethiopia, Amharic is the lingua franca and the most literary language ser dium of instruction in the education system of the country for a long per uses Ethiopic alphabet and has 34 base characters along with modificatio spective base characters. The alphabet is conveniently written in a tabu seven columns. The first column represents the basic form with vowel ኧ /ə/ six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following mo /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labializ such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon colon), etc. It also borrows some punctuation marks such as '?' and '!' from bet. Although Ethiopic alphabet has numeral system, the Arabic numeral sy most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be gener inflectional and derivational processes from other word forms. Many sur words can be formed from a base form through complex affixation, redup Semitic stem interdigitation. Amharic words can be marked for a number For example, a verb can be marked for a combination of person, case, gen tense, aspect, and mood. An Amharic word might take up to four prefixes fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwa constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negat causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and fou ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction of words can be gener-ated from an Amharic root or its stems by changing characters in a stem or root, inserting vowels between root radicals, redupl the characters of the stem or word itself, and by adding affixes on stems [ multiple stem templates for verbal words. However, all variants have representation template. The major-ity of words in the language are generate The rest of this paper is organized as follows. Section 2 describes Amharic langua and its morphology. Section 3 discusses related work. In Section 4, we present the pr posed Amharic IR system architecture along with various options to represent Amhar documents and queries. Section 5 presents the evaluation framework of the propos Amharic adhoc retrieval system including the presentation of the resources and corpor experimental setup, and experimental results. In Section 6, we present our conclusio and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spok Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken Ethiopia, Amharic is the lingua franca and the most literary language serving as a m dium of instruction in the education system of the country for a long period. Amhar uses Ethiopic alphabet and has 34 base characters along with modifications on the r spective base characters. The alphabet is conveniently written in a tabular format seven columns. The first column represents the basic form with vowel ኧ /ə/ and the oth six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characte such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its ow punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (prefa colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alph bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rath most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated throug inflectional and derivational processes from other word forms. Many surface forms words can be formed from a base form through complex affixation, reduplication, an Semitic stem interdigitation. Amharic words can be marked for a number of function For example, a verb can be marked for a combination of person, case, gender, numbe tense, aspect, and mood. An Amharic word might take up to four prefixes and five su fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plur object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousan of words can be gener-ated from an Amharic root or its stems by changing the shape characters in a stem or root, inserting vowels between root radicals, reduplicating one the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There a multiple stem templates for verbal words. However, all variants have a single ro The rest of this paper is organized as follows. Section 2 describes Amharic lan and its morphology. Section 3 discusses related work. In Section 4, we present th posed Amharic IR system architecture along with various options to represent Am documents and queries. Section 5 presents the evaluation framework of the pro Amharic adhoc retrieval system including the presentation of the resources and co experimental setup, and experimental results. In Section 6, we present our conc and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently hav estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly s Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spo Ethiopia, Amharic is the lingua franca and the most literary language serving as dium of instruction in the education system of the country for a long period. Am uses Ethiopic alphabet and has 34 base characters along with modifications on t spective base characters. The alphabet is conveniently written in a tabular form seven columns. The first column represents the basic form with vowel ኧ /ə/ and the six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modificatio /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized char such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also it punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (p colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin a bet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated th inflectional and derivational processes from other word forms. Many surface for words can be formed from a base form through complex affixation, reduplication Semitic stem interdigitation. Amharic words can be marked for a number of func For example, a verb can be marked for a combination of person, case, gender, nu tense, aspect, and mood. An Amharic word might take up to four prefixes and fiv fixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨn constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixe ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thou of words can be gener-ated from an Amharic root or its stems by changing the sh characters in a stem or root, inserting vowels between root radicals, reduplicating the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. The multiple stem templates for verbal words. However, all variants have a singl /, /gor 3 of 29 unavailability of full-fledged low-level Amharic NLP tools makes it notated corpus automatically. Moreover, there is lack of standard aking it a major impediment to the development of Amharic IR and tive of this research work is: (1) to promote publicly accessible Amding a standard test collection for IR, morphologically annotated d stopwords list; and (2) to design Amharic IR system by investipresentation of documents and queries considering both root-based epresentations. aper is organized as follows. Section 2 describes Amharic language Section 3 discusses related work. In Section 4, we present the prostem architecture along with various options to represent Amharic ies. Section 5 presents the evaluation framework of the proposed al system including the presentation of the resources and corpora, and experimental results. In Section 6, we present our conclusion her research directions. ystem orking language of the government of Ethiopia currently having an of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken he world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in the lingua franca and the most literary language serving as a mein the education system of the country for a long period. Amharic et and has 34 base characters along with modifications on the reters. The alphabet is conveniently written in a tabular format of irst column represents the basic form with vowel ኧ /ə/ and the other odifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ ample, the base character በ /bə/ has the following modifications: ቡ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface rrows some punctuation marks such as '?' and '!' from Latin alphaic alphabet has numeral system, the Arabic numeral system is rather by Amharic. gy plex morphology where many words could be generated through vational processes from other word forms. Many surface forms of from a base form through complex affixation, reduplication, and itation. Amharic words can be marked for a number of functions. can be marked for a combination of person, case, gender, number, od. An Amharic word might take up to four prefixes and five sufample, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is ur prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ ro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ar subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural r-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands r-ated from an Amharic root or its stems by changing the shape of r root, inserting vowels between root radicals, reduplicating one of stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are gora/ and /n k' m The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated population of over 117 million [START_REF]Ethiopian Population[END_REF]. It is the second most commonly spoken Semitic language in the world after Arabic [START_REF] Hetzron | Ethiopian Semitic: Studies in classification[END_REF]. Although many languages are spoken in Ethiopia, Amharic is the lingua franca and the most literary language serving as a medium of instruction in the education system of the country for a long period. Amharic uses Ethiopic alphabet and has 34 base characters along with modifications on the respective base characters. The alphabet is conveniently written in a tabular format of seven columns. The first column represents the basic form with vowel ኧ /ə/ and the other six orders represent modifications with vowels in the order of ኡ /ʔu/, ኢ /ʔi/, ኣ /ʔa/, ኤ /ʔe/, እ /ʔɨ/, and ኦ /ʔo/. For example, the base character በ /bə/ has the following modifications: ቡ /bu/, ቢ /bi/, ባ /ba/, ቤ /be/, ብ /bɨ/, and ቦ /bo/. Furthermore, there are labialized characters such as ቧ /bwa/, ሟ /mwa/, ቷ /twa/, ቋ /qwa/, ሯ /rwa/, etc. The language has also its own punctuations such as '።' (full stop), '፣' (comma), '፤' (semicolon), '፥' (colon), '፦' (preface colon), etc. It also borrows some punctuation marks such as '?' and '!' from Latin alphabet. Although Ethiopic alphabet has numeral system, the Arabic numeral system is rather most commonly used by Amharic.

Amharic Morphology

Amharic has complex morphology where many words could be generated through inflectional and derivational processes from other word forms. Many surface forms of words can be formed from a base form through complex affixation, reduplication, and Semitic stem interdigitation. Amharic words can be marked for a number of functions. For example, a verb can be marked for a combination of person, case, gender, number, tense, aspect, and mood. An Amharic word might take up to four prefixes and five suffixes [START_REF] Alemayehu | Stemming of Amharic words for information retrieval[END_REF]. For example, the word ያላስተሳሰርኳቸውንና /jalasɨtəsasərɨkwatʃəwɨnɨna/ is constructed from four prefixes (የ /jə preposition/, አል /ʔəl ɨ negation/, አስ /ʔəsɨ causative/, ተ /tə recipro-cal/); the perfective verb (አሰር /ʔəsərɨ 'tie'/); and four suffixes (ኩ / ku first person singular subject marker for perfect verb/, አቸው /ʔətʃəwɨ third person plural object marker for per-fective verb/, ን /nɨ accusative/, and ና /na conjunction/). Thousands of words can be gener-ated from an Amharic root or its stems by changing the shape of characters in a stem or root, inserting vowels between root radicals, reduplicating one of the characters of the stem or word itself, and by adding affixes on stems [START_REF] Abate | Development of Amharic morphological analyzer using memory-based learning[END_REF]. There are The rest of this paper is organized as follows. Section 2 describes Amharic language and its morphology. Section 3 discusses related work. In Section 4, we present the proposed Amharic IR system architecture along with various options to represent Amharic documents and queries. Section 5 presents the evaluation framework of the proposed Amharic adhoc retrieval system including the presentation of the resources and corpora, experimental setup, and experimental results. In Section 6, we present our conclusion and put forward further research directions.

Amharic Language

Amharic Writing System

Amharic is the working language of the government of Ethiopia currently having an estimated
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