Enchalew Y Ayalew
email: enchalew.yifru@aastu.edu.et

Laure Vieu
email: laure.vieu@irit.fr

Million M Beyene
email: million.meshesha@aau.edu.

The Need for a Novel Approach to Design Derivation Lexicon for Semitic Languages

Keywords: Semitic Computational Morphology, Lexicon Design, Derivation Lexicon

Morphology knowledge is relevant in language learning, information retrieval and natural language processing. Derivation lexicons are organized and comprehensive collections of the morphological variants of a language's vocabulary. These lexicons can be developed either through analysis-based synthesis of large text corpora or through synthesis of surface forms from roots, stems, lemmas and morphological rules. Much of the research attempted in developing derivation lexicon for Indo-European languages, which are concatenative, focus on analysis-based synthesis, as they do have well-developed preprocessing tools and organized text corpora. However, the methods for these languages are not appropriate for non-concatenative languages such as Semitic languages. Moreover, most of the Semitic languages, except Arabic and Hebrew, do not have well-developed text corpora and language processing tools. Hence, a novel approach that can cater for the root-pattern and rich morphology of these languages is necessary. This paper is therefore a comprehensive survey of the literature, an analysis motivating an innovative and generic morphological synthesis approach with illustrated architecture. It is part of a larger project tailored for designing an innovative, generic, approach to derivation lexicon development for Semitic languages.

Introduction

Lexical ontologies such as dictionaries, thesauri or WordNets have been used to improve various computational applications, such as information retrieval (IR) and natural language processing (NLP) [START_REF] Jurafsky | Speech and Language Processing: An Introduction to Natural Language Processing[END_REF]. Yet, these resources remain short of addressing certain NLP and IR tasks. This motivated researchers to build derivation lexicons, i.e., organized clusters of part-of-speech (POS) variants; the -categorical variation of a word with a certain part-of-speech is a derivationally-related word with possibly a different part-of-speech‖ [17, p.1]. In an online version of CatVar 2.0, a derivation lexicon for English, the POS variants of ‗break' are categorized into 39 clusters 1 , indicating the word, the POS and the source lexicon in tabular form. For example, two clusters of -break‖ include break N , break V , broken Adj , breaker N , breakage N , breakers N , breaking N , and breaking Adj as one cluster; and the second which encompasses breakable N , breakable Aj , breakability N , breakableness N . [START_REF] Habash | A Categorical Variation Database for English[END_REF] Noted that link-ability 2 principle was used to create clusters (see details on link-ability in section 4.2).

As we shall see below, due to the successful use of morphological information in improving NLP and IR tasks, many language-specific derivation lexicons have been developed and are under development. Yet, to our knowledge, there are no derivation lexicons for any of the Semitic Languages; and hence in this paper we propose a novel approach suited to design derivation lexicon for Semitic Languages.

The rest of the paper is organized as follows. In section 2, we briefly introduce Semitic Languages and elaborate on their shared features. Section 3 looks at the major applications of derivation lexicons. Section 4 describes common approaches to nonconcatenative, including Semitic languages, morphological computations and existing approaches to derivation lexicon development. Section 5 presents our proposed approach and finally, in Section 6 future work directions are highlighted.

Overview of Semitic Languages

Semitic languages belong to the Afro-Asiatic family of languages which mainly cover areas such as the Middle East, North and East Africa. They used to be spoken, as back in time as the 2500BC, by populations who lived in areas spanning from Ethiopia, Sudan and Saudi Arabia in the south to today's Syria in the North and what is known today as Iran and Iraq in the East [START_REF] Shimron | Semitic languages: Are they really root-based?[END_REF].

According to [START_REF] Shimron | Semitic languages: Are they really root-based?[END_REF], these languages are grouped into East and West Semitic. While the East Semitic languages spoken today are Amorite and Eblaite, the West Semitic group has more diverse languages and hence is sub-classified as Central and Southern Semitic. Surviving languages in the Central Semitic sub-group are Arabic and North Western Languages such as Hebrew and Aramaic. The languages that constitute the Southern Semitic sub-group are South Arabian (spoken in Yemen and Oman) and Western South Semitic which are spoken in Ethiopia. The Ethio-Semitic cluster con-stitutes the Northern (such as Tigre, Tigrinya and Geeze-an old liturgical language) and Southern (Amharic, Harari, Gurage, Chaha and Gura) languages. [START_REF] Bender | Amharic Verb Morphology: A Generative Approach[END_REF] Also included Argoba to the list.

The most widely-spoken Semitic languages today are Arabic, Amharic, Hebrew, Tigrigna, Syriac and Maltese-an Arabic dialect influenced by Italian language [START_REF] Zitouni | Preface[END_REF], Modern Aramaic, Mandaic and different dialect of Modern South Arabian languages [START_REF] Shimron | Semitic languages: Are they really root-based?[END_REF]. [START_REF] Zitouni | Preface[END_REF] Noted that Arabic and Amharic are-respectively-the first and second widely spoken Semitic languages. Hebrew is the fourth widely spoken language, next to Tigrigna, and is also relatively well researched like Arabic.

Common Features

Languages that have closely-related features enable not only in speeding up language learning but also in sharing and adapting computational solutions easily. This is true of Semitic languages as they are related in their phonology, morphology, lexicon and syntax [START_REF] Shimron | Semitic languages: Are they really root-based?[END_REF]. Narrowing our focus on morphology and lexicon tells us that these languages have complex morphologies and rich verbal lexicon. In addition, words of the same root have related semantics. These common features are illustrated taking Arabic, Amharic and Hebrew as examples.

Complex Morphology. Word formation in Semitic languages is so complex that it intensively involves both inflection and derivation. While derivation is mainly nonconcatenative, inflection is dominated with suffixation and prefixation in addition to the reduplication of certain characters in the stem [START_REF] Baye | የአማርኛ ስዋሰው:የተሻሻለ ሶስተኛ እትም. 3rd edn[END_REF]. Inflection is meant to create variants of a lemma in the same syntactic category (showing person, number, tense, gender, etc). On the other hand, derivation helps to create new lemmas with different syntactic categories (nouns, verbs, adjectives or adverbs) from verbal roots, patterns and linguistic rules. While roots are generally consonant characters, the pattern is a sequence of consonant-vowel (like CVC, CVCC, CVCVCV …) forms where actual consonant and vowel characters will be inter-digitized using rules to form stems or lemmas. When stems/lemmas are inflected, they form surface forms. For example, in Amharic from the tri-literal root ‗m-k-r': standing for ‗advise', we can generate plenty of POS variants. To mention some, CVCC: -mIkr N ‖3 -advice, CVCVCV: -mekari N ‖-adviser, CVCCVCV: -mekkere V ‖advised, C-CVCCVCV: -te-mekkere Adj ‖advised or C-CVC[C] VCV: -te-mek[k]ari N ‖-advisee, V-CCVCVC-V: -a-mmakari Adj ‖-advisory, V-CCVCVC-V: -a-mmakari N ‖-advisory, etc.

Lexicon Rich in Verbs. The complexity of word formation in Semitic languages' leads to a vocabulary rich in verbs. For instance, about 75% to 80 % of Amharic dictionary entries consist of verbs or their de-verbal nouns/adjectives and hence an -exhaustive verb list is a substitute for a complete dictionary… the verb is the language‖ [43, p.73]. There are even a larger proportion of verbs in the Arabic vocabulary than in Amharic, i.e., -verbal roots and their derivative nouns and participles make up 80% to 85% of all Arabic words‖ 4 . It is also noted that -Hebrew is primarily a verbal lan-guage‖ and -every Hebrew verb (and every noun) is based on a three-consonant root … which encodes the basic semantic meaning or purpose of a given verb or noun‖ 5 .

All verbs and most nouns have roots [START_REF] Shimron | Semitic languages: Are they really root-based?[END_REF]; hence a verbal root serves to produce not only verbs but also nouns. In addition, adjectives are also produced from verbal roots [START_REF] Baye | የአማርኛ ስዋሰው:የተሻሻለ ሶስተኛ እትም. 3rd edn[END_REF], in a manner similar to nouns [START_REF] Gasser | HornMorpho: A System for Morphological Processing of Amharic, Oromo, and Tigrignya[END_REF]. However, prepositions, conjunctions, simple nouns and adjectives, also known as -primitives‖ [START_REF] Boudelaa | Structure, Form, and Meaning in the Mental Lexicon: Evidence from Arabic[END_REF], are not derivable from verbs. For example, in Amharic, the noun ‗bEt: house' and the adjective ‗blIh: smart'are not derivable from verbs [START_REF] Baye | የአማርኛ ስዋሰው:የተሻሻለ ሶስተኛ እትም. 3rd edn[END_REF]. In general, a Semitic lexicon built based on verbal roots covers most of a language's vocabulary entries.

Semantic Relatedness. Words derived from a given root are, broadly speaking, related in meaning [START_REF] Boudelaa | Structure, Form, and Meaning in the Mental Lexicon: Evidence from Arabic[END_REF][START_REF] Shimron | Semitic languages: Are they really root-based?[END_REF]. [START_REF] Boudelaa | Structure, Form, and Meaning in the Mental Lexicon: Evidence from Arabic[END_REF] Indicated that the Arabic words kataba, kaataba, maktabun, maktabatun, kitaabun, maktuubun, and kuttaabun are derived from the same root k-t-b, representing not only similar morphological and phonological relation but also, at various degrees, similar semantic contents such as the semantic meaning of writing. The equivalent English meanings respectively are write, correspond, office, library, book, destiny, and Koran school, which are not morphologically related. Except destiny, the rest of the terms are strongly related in meaning. Destiny is unrelated in meaning from the rest because it might be the result of -semantic drift‖ -deviation mainly due to -usage over time‖ [START_REF] Diab | Semantic Processing of Semitic Languages[END_REF]. The Hebrew root ‗k-t-b' produces surface forms which are related in meaning like ‗ktb'/katav/: write, ‗hktib'/hiktiv/: dictate,‗hktbh'/haktava/: dictation, mktbh: writing desk [START_REF] Habash | A Categorical Variation Database for English[END_REF]. Similarly, the Hebrew words zimər (‗sing'), zamar (‗singer') and ziməra (‗singing) are derived from the root z-m-r [START_REF] Ravid | Word-Level Morphology: A Psycholinguistic Perspective on Linear Formation in Hebrew Nominals[END_REF].

In Amharic sella (‗sharp, have keen edge'), sale(‗sharpen'), selessele (‗wear thin, weak'), sellele (‗become paralyzed, withered') with a common meaning of slender are derived from same root ‗s-l' [START_REF] Bezza | The Submorphemic Structure of Amharic: Toward a Phono-Semantic Analysis[END_REF] 6 . The Arabic root ‗k-t-b' does have the equivalent Amharic root S-h-f [5, p.122]. It is derived from the Geez Sehafe7 , which in Amharic means Safe, referring to -he wrote‖. Derivations from this root include meShaf (‗Book'), meSaSaf (‗correspond'), meSaf(‗write'), Shuf/Sfet/ (anything written or inscription), Sehafi (writer), meSafia(‗instrument for writing'), aSaSaf (‗manner/style of writing'), maSaf (‗dictate').

Although words of the same root do have one shared lexical meaning [START_REF] Boudelaa | Structure, Form, and Meaning in the Mental Lexicon: Evidence from Arabic[END_REF] and the root stands out as the core lexical content of words [START_REF] Ravid | Word-Level Morphology: A Psycholinguistic Perspective on Linear Formation in Hebrew Nominals[END_REF], the root represents one aspect of lexical meaning shared by the derived stems [START_REF] Bezza | The Submorphemic Structure of Amharic: Toward a Phono-Semantic Analysis[END_REF]; the rest of a word's meaning for these languages come from templates [START_REF] Boudelaa | Structure, Form, and Meaning in the Mental Lexicon: Evidence from Arabic[END_REF].

Application of Derivation Lexicons

Language learning and computation (IR and NLP) equally benefit from using morphology information. The first sub-section illustrates benefits for language learning; the second and third sub-sections address the merits of morphology in computation.

Language Learning

Derivation morphology knowledge speeds up the ability of children to learn new vocabulary [START_REF] Bertram | The Role of Derivational Morphology in Vocabulary Acquisition: Get by with a Little help from my Morpheme Friends[END_REF] and empower the analysis and understanding of language learning from infancy to adulthood [START_REF] Levie | The Route to the Derivational Verb Family in Hebrew: A Psycholinguistic Study of Acquisition and Development[END_REF]. It enhances second language learning [START_REF] Freynik | L2 Processing of Arabic Derivational Morphology[END_REF], helps in reading and spelling accuracy [START_REF] Angelelli | The Effect of morphology on spelling and reading accuracy: a study on Italian Children[END_REF], a key to the access and construction of sentence syntactic structure as well as organizes internal lexicons [START_REF] Tayler | The Role of Derivational Suffixes in Sentence Comprehension[END_REF].

Language learners detect and understand morphological variants easily by analyzing words into their morphemes/morphological sub-structures/, particularly detecting the root in the derived forms and then give definitions on the basis of the root [START_REF] Bertram | The Role of Derivational Morphology in Vocabulary Acquisition: Get by with a Little help from my Morpheme Friends[END_REF].

Information Retrieval (IR)

Effective IR systems allow the retrieval of documents in a collection that match user queries. However, IR systems are unable to fully address user information need either due to polysemy-a situation where there are multiple possible meanings for a word/phrase (e.g., bank-‗financial organization' vs. bank-‗river side') -or synonyms-multiple words having the same meaning (e.g., student vs pupil). While polysemy may confuse the IR system to retrieve irrelevant documents, synonymy may not allow the retrieval of all relevant documents in a collection. Morphological variants are relevant both at indexing and querying time to address part of these problems. During document indexing morphological variants are conflated to a single indexing term, thereby allowing the retrieval of all possible documents with the variants. During querying time, users can reformulate their search by considering system suggested morphological variant alternatives.

In general, morphology information enhances IR through query expansion and conflation-based document indexing [START_REF] Moreau | Automatic Morphological Query Expansion Using Analogy-Based Machine Learning[END_REF]; CatVar is relevant for IR research [START_REF] Hulden | Foma: A Finite-State Compiler and Library[END_REF].

Natural Language Processing (NLP)

In NLP, morphology knowledge is useful in machine translation, spell check, lexicon compilation, POS tagging and sentence construction [START_REF] Kibur | Design and Development of Automatic Morphological Synthesizer for Amharic Perfective Verbs[END_REF]. CatVar improves natural language generation and machine translation [START_REF] Habash | A Categorical Variation Database for English[END_REF], textual and lexical entailment [START_REF] Berant | Learning Entailment Relations by Global Graph Structure Optimization[END_REF], helps to enhance and induce semantic role resources for predicates of nouns [START_REF] Meyers | Annotating Noun Argument Structure for NomBank[END_REF] and paraphrase identification [START_REF] Mohamed | A Hybrid Approach for Paraphrase Identification based on Knowledge-Enriched Semantic Heuristics[END_REF]. It has also the potential in lexicon construction and enhancing WordNets [START_REF] Habash | A Categorical Variation Database for English[END_REF]. The German DEriveBase is used in improving similarity prediction and synonym choice [START_REF] Pad´o | Derivational Smoothing for Syntactic Distributional Semantics[END_REF].

Approaches to Derivation Lexicon Development

Morphological computations are tailored either to form a word from the parts, i.e., synthesis/generation or to break up a word into its components, i.e. analysis. Most NLP and IR research focus on analysis, by taking words of a text and breaking them up into their components and whenever necessary reproducing words from these components, thereby merging analysis and synthesis together [START_REF] Gasser | HornMorpho: A System for Morphological Processing of Amharic, Oromo, and Tigrignya[END_REF]. When the goal is to develop a lexicon, however, analysis is conducted on finite text corpora and thus unable to produce comprehensive vocabulary entries. This is, particularly, true for most Semitic languages which do not have large-sized, organized corpora. Moreover, analysis involves using tools for a number of pre-processing phases such as sentence detection, tokenization, POS tagging and stemming or lemmatization.

On the other hand, synthesis takes on a collection of finite ‗primitive' linguistic components-i.e., roots, stems or lemmas, along with linguistic rules-and then build words resulting in a comprehensive coverage of a language's vocabulary. This is more so for Semitic languages, where word formation is based on the interdigitations of consonantal roots with vowels, based on patterns, as explained in section 2.

Both synthesis and analysis-based synthesis have the downside of producing outof-vocabulary words. Machine learning-decision trees implemented in Weka8 technique was used to reduce invalid word entries as was the case in [START_REF] Rodriguez | Arabic WordNet: Current State and Future Extensions[END_REF]. We plan to test a similar method. Alternatively, we also planned to experiment on a less data intensive valid word prediction method. This method should depend only on small learning seed data-instead of large corpora-from which the required -full valid‖ vocabulary of a language is built. This is the direction adopted in this project.

In the remaining subsections, we first briefly look into non-concatenative finite state morphology (FSM). It is considered appropriate for Semitic Language morphology processing. This is followed by the specific approaches used in developing derivation lexicons for Indo-European languages; they focus mainly on analysis-based generation. Lastly, we look at the approaches used in generating various lexical resources for Semitic languages.

Non-concatenative Finite-State Morphology

The concept of finite-state morphology was proposed in the early 1980s. It was conceived to overcome the computational difficulties of morphologically complex languages in general. The idea was first tested on the Finish Language [START_REF] Koskenniemi | Two-level morphology: A General Computational Model for Word-form Recognition and Production[END_REF] following a -Two-Level Morphology‖ approach. The model is based on a lexicon, set of twolevel rules processed in parallel and a small set of finite state automata (FSA) [START_REF] Shimron | Semitic languages: Are they really root-based?[END_REF]; it handles both analysis and generation. However, this approach was not sufficient for Semitic languages which require more than two levels of representation.

Hence, [START_REF] Kay | Nonconcatenative Finite-State Morphology[END_REF] proposed multi-level implementation based on the theory of autosegmental [START_REF] Mccarthy | A Prosodic Theory of Non-Concatenative Morphology[END_REF] approach to Semitic morphology processing. It outlined a quadruple-tape finite state machine to describe the independent morphemes of Arabic, making it more palatable for other Semitic languages as well. However, the rules to control tape manipulation were arbitrary. Therefore [START_REF] Kiraz | Multitiered Nonlinear Morphology Using Multitape Finite Automata: A Case Study on Syriac and Arabic[END_REF] came up with -attractive rule‖ control of the four-level tapes by applying it to Arabic and Syriac languages.

Later on, [START_REF] Habash | Morphological Analysis and Generation for Arabic Dialects[END_REF] extended [START_REF] Kiraz | Multitiered Nonlinear Morphology Using Multitape Finite Automata: A Case Study on Syriac and Arabic[END_REF]'s idea by adding a fifth tape, with the goal of developing the Arabic morphological analyzer and generator named MAGEAD. The five levels have different purposes [START_REF] Habash | Morphological Analysis and Generation for Arabic Dialects[END_REF]: level l represents patterns and affixation morphemes, level 2 stands for roots, level 3 stands for vocalism, levels 4 and 5, respectively, stand for phonology and orthography. However, it is learnt that the complexity of transitions between levels exponentially increases with the number of tapes [START_REF] Hulden | Revisiting Multi-tape Automata for Semitic Morphological Analysis and Generation[END_REF]. Therefore, [START_REF] Hulden | Foma: A Finite-State Compiler and Library[END_REF] tried to simulate the representation of multiple levels with a singletape, claimed to be realizable on available standard finite-automaton toolkits. On the other hand, the single FSA simulation has resulted in search speed limitations during surface forms generation and search-based analysis [START_REF] Hulden | Revisiting Multi-tape Automata for Semitic Morphological Analysis and Generation[END_REF]. This indicates that simulating multiple tapes into a single tape simply makes the problem cyclic.

To tackle the inherent efficiency-problem of FSA for multi-tape representation, a Finite-State Registered Automata (FSRA) was proposed [START_REF] Cohen-Sygal | Finite-State Registered Automata for Non-Concatenative Morphology[END_REF]. It involves supplementing existing FSA with finite memory/registers so as to save space. The registers are made small in number and help to avoid the need to repeat paths in order to memorize a finite set of symbols. FSRA is efficient, reducing the quadratic time O(r*p) for traversing arcs in an ordinary FSA to linear time O(r+p), where r and p are the number of roots and patterns, respectively.

Indo-European Languages

Indo-European languages have concatenative word formation morphology. These languages rely on analysis based synthesis as the dominant approach to derivation lexicon development. This may be attributed to the availability of sufficient corpora, effective preprocessing tools and the relative -simplicity‖ of reducing words to basic forms-stems or lemmas. In the following paragraphs, we describe the most influential derivation lexicon development research for this group of languages.

A suffixation-based probabilistic unsupervised machine learning technique was used to strip off suffixes from words of an inflectional lexicon aiming to produce French's derivational families [START_REF] Gaussier | Unsupervised Learning of Derivational Morphology from Inflectional Lexicons[END_REF]. The main intuition to clustering words to relational families is to add words into a family as long as they are ‗p' similar and relate them with suffix pairs. This is assuming suffix pairs from different families don't cooccur. ‗P' stands for the number of similar sequenced characters between derived forms. The intuition is implemented using hierarchical agglomerative clustering and minimum/maximum spanning tree graphs respectively, for identifying derivational families and suffixation. There is no evidence if effort was made for sub-clustering of a word's variants; the proportion of any singleton clusters in the result is not reported.

[17] Developed a large-scale categorical database for English, known as CatVar. It was based on pre-existing data sources and tools: corpora, tree banks, lexicons and stemmer. The clustering of derived and inflected forms is based on three link-ability concepts: natural link-ability (pairs of words whose form doesn't change across cate-gories like zip V , zip N ), Porter link-ability (words linkable by reduction to a common Porter stem) and CatVar link-ability (link-ability of two words appearing in the same CatVar cluster). It is reported that near to half of CatVar's clusters are singleton entries. Of which, 75% are nouns and one-fifth is adjectives. Unlike this, derivationally related senses/forms in the manually built wordNet 9 consist of two or more POS variants (noun-verb, noun-adjective, verb-adjective; noun-verb-adjective). Unless a cluster has at least two POS variants, the lexicon becomes a simple word list with little purpose.

Inspired by the applicability of CatVar in IR and NLP tasks, [START_REF] Zeller | DERIVEBASE: Inducing and Evaluating a Derivational Morphology Resource for German[END_REF] developed a lemma-based derivational knowledge base, i.e., DERIVBASE, for German using a large German web corpus, pre-existing POS tagger, parser and lemmatizer. The induction of derivational families for nouns, verbs and adjectives was based on rules from text books. The rules capture intra-POS and inter-POS derivations from POStagged lemmas and paradigms (zero-derivation 10 , prefixes, suffixes, circumfixes and stem changes). Derivation rules are set for POS-pairs as: N-N, N-A, N-V, A-A, A-V, V-V. The clustering rule is formulated in such a way that a binary derivation relation between two lemma-paradigm pairs is considered valid if the second pair can be derived from the first one. Of the total 239680 derivational families, 17799(around 7.4%) reported to be non-singleton clusters where as the majority (most reported to be compound nouns), i.e., 221881 (>92%) are singleton clusters. [START_REF] Snajder | DERIVBASE.HR: A High-Coverage Derivational Morphology Resource for Croatian[END_REF] And [START_REF] Vodolazsky | DeriveBase.Ru: A Derivational Morphology Resource for Russian[END_REF] were motivated by the outcome of DERIVBASE and hence used similar methods in developing the derivation lexicons for Croatian and Russian Languages respectively.

In general, singleton clusters are the major drawback of both CatVar and DERIVBASE. This important problem calls for incorporating innovative intuitions rather than relying only on the link-ability concepts of CatVar or a single intuition as is the case in DERIVBASE or French's derivational families. Considering multiplepossibly hierarchical-intuitions including linguistic once can reduce the problem.

Semitic Languages

Our effort to review the literature on derivation lexicons for Semitic Languages reveals that such resources are not yet in place. However, we found several purpose specific lexical resources; showing derivation as an important approach for resource building. In this sub-section we look at these efforts. The generation-based methods (including the analysis-based generation) help us to learn about achievements and gaps on derivation lexicon development. Our discussion excludes any manuallydeveloped resources including the lexicons of BAMA 11 and SAMA 12 .

[3] Developed a large Arabic lexicon for use in an open source FST-based, bidirectional analyzer and generator for Arabic known as AraComLex 2.1 13 , with the goal of overcoming the obsolete entries in SAMA lexicon. It was based on Arabic Gigaword 9 https://wordnet.princeton.edu/download/current-version, last accessed 2021/06/24 10 Zero-derivation results in POS variants of identical forms (e.g, the farm => to farm; ) 11 Buckwalter Arabic Morphological Analyzer 12 Standard Arabic Morphological Analyzer 13 AraComLex 2.1. is an open source, lemma-based, analysis and generation FST for MSA. corpus and news articles from the Al-Jazeera web site. MADA 14 was used for preannotation such as to lemmatize, diacritize, POS-tag and disambiguate the input data. The use of a multilayer perceptron machine learning in Weka enabled AraComLex 2.1 to have better coverage from its predecessor, i.e., AraComLex 1.0, but slightly lower in coverage from that of SAMA.

[2] Proposed a simple, rule-based, algorithm with the goal of developing an inflectional analysis-based Arabic word generator based on input word from the user. The input is analyzed to its stem and inflectional components. These components then go through generation.

Unlike [START_REF] Aqel | Building an Arabic Word Generator[END_REF][3], the researches discussed hence forth are based on synthesizing morphological components as input. The early attempt along this line is [START_REF] Wedekind | Which Form Predict all other Best? Variation on the Amharic Verb -Theme‖[END_REF] which is a rule-based approach used to generate surface forms alternatively either from Amharic roots or perfect & infinitive forms. The goal was to determine which of the three predicts the two others best. This was used to understand the impact of such derivation in language acquisition/learning. Morphology rules, applied to the 42 Amharic verbclasses of [START_REF] Bender | Amharic Verb Morphology: A Generative Approach[END_REF], along with the 1280 Amharic roots from the same source were implemented in BASIC. It is shown that the program with the root as input was capable of correctly deriving infinitives of all verbs using eight rules; and through the infinitive, all other verbal forms, indicating that the root has the advantage as it predicts the other verbal forms unambiguously.

[23] Developed a synthesizer for Amharic verb forms from manually compiled 145 tri-literal perfective verb roots. Derivation rules, suffixation, vowel and consonant change as well as platalization rules were considered as input to the synthesizer. The synthesizer was complemented with a neural network method to predict new roots not available in the root database. The limitations of this study are too shallow testing and focus only on perfective verbs, among others. Hence, the report included several recommendations like the need to consider other verb types and develop full-fledged synthesizer that can be applied in machine translation, spell checking, lexicon compilation, POS tagging and sentence construction, among others. [START_REF] Gibbon | A Complete FS Model for Amharic Morphographemics[END_REF] Developed an XFST-based morpho-graphemic rule-based model generator/analyzer for Amharic nouns (loan and native nouns included), verbs and adjectives. The generation component accepts roots (from bi-radical to quad radicals) as inputs undergoing respectively through vowel intercalation, concatenating input affixes, handle phonological alterations and finally generate the grapheme form. Similarly, [START_REF] Sisay | Amharic Verb Lexicon in the Context of Machine Translation[END_REF] also developed an XFST-based analyzer/generator to produce Amharic verblexicon for use in a machine translation experiment. Report shows the generation of main verbal-forms from three-to-five radical roots using rules. The report doesn't show the derivation of nouns and adjectives. Both [START_REF] Gibbon | A Complete FS Model for Amharic Morphographemics[END_REF] and [START_REF] Sisay | Amharic Verb Lexicon in the Context of Machine Translation[END_REF] indicate neither the size and source of roots and rules nor the volume of records created. [START_REF] Habash | Large Scale Lexeme Based Arabic Morphological Generation[END_REF] Developed a large-scale lexeme-based Arabic morphological generation system known as Aragen. It is based on the database (prefix, stem, and suffix) of BAMA with a new engine performing generation instead of analysis. Input data was extracted from the UN Arabic-English corpus. The baseline generator used a simple concatena-tive word structure rule and a small lexicon with 70 entries. Evaluation report shows that Aragen's performance was much better than the base line both in undergeneration and over-generation errors.

[37] Developed a rule-based morphological generator for Arabic with the goal of using it in an interlingua-based machine translation project for spoken dialogues. It generates inflected nouns/adjectives, verbs and particles from stems and grammatical features. Although it is indicated that evaluations were satisfactory, it was not quantified to understand the extent of the system's proformance. The generator is reported to have been successfully used in other applications such as Arabic-Audio Indexing and intelligent computer-assisted learning for Arabic. Intending to semi-automatically extend AWN (Arabic WordNet), [START_REF] Rodriguez | Arabic WordNet: Current State and Future Extensions[END_REF] used lexical rules, as regular expressions, to produce derived forms (nouns, verbs and adjectives) from the roots of 2296 verbs in Arabic WordNet. To filter out over-generated forms, decision tree classifiers in Weka toolbox were used. The learning was based on Arabic Gigaword corpus (to get relative frequency of each inflected form), Arabic NMSU dictionary entries (to check presence of base form and its POS tag) and positive /negative examples.

[13] Developed a tool named HornMorph for the analysis and generation of two Semitic languages (Amharic & Tigrigna) and a Cushitic language (Oromo). Focusing on the generation component of Amharic and Tigrigna, rules as FSTs were implemented in python. Input included 1851 verb roots from dictionary and 6471 noun stems (for Amharic) and 602 verb roots for Tigrigna. [START_REF] Neme | A lexicon of Arabic verbs constructed on the basis of Semitic taxonomy and using Finite-State Transducers[END_REF] Has synthesized a lexicon of 15,400 Arabic verbs into 2.5 million inflected forms. Input verb lemmas, grouped into 31 root classes, were extracted from a precompiled full-form (with diacritic markers) dictionary. For each lemma class, inflection rules were implemented using FSTs to produce the surface forms. In a PhD research, [START_REF] Martinez | A Computational Model of Modern Standard Arabic Verbal Morphology based on Generation[END_REF] used a rule-based model, to synthesize Arabic verbal lemmas and inflected forms from roots and templates in an effort to develop a morphological analyzer and generator. An input lexicon of 15452 verb lemmas-for 3706 roots-was used to generate a lexicon of more than 1.68 million verbal inflected forms.

[18] Derived the surface forms of twenty simple present tense Amharic verbs that begin only with consonants. It is based on the theory of network morphology, implemented using the partially object-oriented tool, DATR. The twenty verbal templates followed four stem patterns such as CVCCVCV, CVCVCV, CV and CVCVCVCV. The system handled the addition and deletion of phonological changes, which happen when the sixth order ‗I' in a stem follows the consonants ‗d, n, r, z or l'(alveolars), deletion occurs. On the other hand, when the fourth order form follows m, b, l, r, g, q, t or c, it changes to a third order form and ‗a' is added (addition takes place). Both changes also cause change in the root and pattern template. The assessments of the aforementioned papers on Semitic languages show that derivation of inflected verbal, adjectival or noun forms are possible from verb roots using linguistic rules. [START_REF] Wedekind | Which Form Predict all other Best? Variation on the Amharic Verb -Theme‖[END_REF]'s use of the Amharic derivation rule set and pre-existing root corpora from [START_REF] Bender | Amharic Verb Morphology: A Generative Approach[END_REF] to derive various verbal forms; and [START_REF] Gasser | HornMorpho: A System for Morphological Processing of Amharic, Oromo, and Tigrignya[END_REF]'s effort in developing an FST for both analysis and generation of Amharic and [Tigrigna] is an encouraging input for Amharic lexicon development research. [START_REF] Kibur | Design and Development of Automatic Morphological Synthesizer for Amharic Perfective Verbs[END_REF]'s attempt to synthesis Amharic verbal forms from roots, though limited, and the outlook towards suggesting for a broader research to develop full-fledged synthesizer for use, for instance, in Amharic lexicon compilation, among others, is an important point. Furthermore, [START_REF] Gibbon | A Complete FS Model for Amharic Morphographemics[END_REF]'s use of FSs to generate Amharic POS variants (nouns, verbs and adjectives) and [START_REF] Sisay | Amharic Verb Lexicon in the Context of Machine Translation[END_REF]'s derivation of verbs from roots and rules further justifies the viability of root-based derivation in Amharic and an important input to resource development. In general, it is important to note that the efforts on Amharic [Ethio-Semitic in general] morphological analysis and generation-including those not reviewed in here due to space economy-are at an experimental stage at large. They are not to the level of building a lexicon of derived forms accessible even for research let alone for general public use. From among the papers on Arabic language synthesis-based derivation, the ones by [START_REF] Martinez | A Computational Model of Modern Standard Arabic Verbal Morphology based on Generation[END_REF] and [START_REF] Rodriguez | Arabic WordNet: Current State and Future Extensions[END_REF] have important ideas to consider particularly in their use of organized rule-set and roots to generate verbs, nouns and adjectives. Moreover, [START_REF] Rodriguez | Arabic WordNet: Current State and Future Extensions[END_REF]'s noise filtering approach is also reported to be effective and hence is encouraging. However, most Arabic generation research reviewed such as [START_REF] Aqel | Building an Arabic Word Generator[END_REF][START_REF] Attia | An Open-Source Finite State Morphological Transducer for Modern Standard Arabic[END_REF][START_REF] Habash | Large Scale Lexeme Based Arabic Morphological Generation[END_REF][START_REF] Neme | A lexicon of Arabic verbs constructed on the basis of Semitic taxonomy and using Finite-State Transducers[END_REF][START_REF] Shaalan | Arabic Morphological Generation from Interlingua: A Rule-based Approach[END_REF] focused on inflection than generation using existing tools and resources. Other than generating surface forms for specific uses or as a research in its own right, none of the attempts discussed on Semitic languages' utilized rule and root-based generation to produce organized lexical resource similar to CatVar or DERIVBASE. Thus, no plan or effort is reported in linking (clustering) POS variants (nouns, adjectives, verbs) of a root into meaningful categories. The main component of research in derivation lexicon development is the clustering of POS variants using various methods like machine learning [START_REF] Gaussier | Unsupervised Learning of Derivational Morphology from Inflectional Lexicons[END_REF], link-ability [START_REF] Habash | A Categorical Variation Database for English[END_REF] and rule-based [START_REF] Zeller | DERIVEBASE: Inducing and Evaluating a Derivational Morphology Resource for German[END_REF].

Proposed Approach

Our understanding-thus far-indicates three important points. Firstly, the morphology of Semitic languages is quite different from Indo-European languages. While the derivation and inflection morphology in the later is concatenative, the former has predominantly non-concatenative derivational and inflectional morphology. This is a challenge to utilize or adapt available NLP tools and algorithms for Indo-European languages to Semitic languages. Secondly, most Semitic languages suffer from the lack of accessible and well-functioning resources and tools for language processing. Thirdly, most of the research in language processing focuses on morphological analysis or analysis-based synthesis. However, we recall that there are few efforts, particularly for Semitic languages, which focused on synthesis-based resource development. This warrants that morphological synthesis-as an important approach in resource development-is of an interest on its own. Moreover, synthesis involves less preprocessing language tools making it more appropriate for most Semitic languages. Semitic languages' research in the generation of lexical resources hasn't yet given any attention to derivation lexicon development. Our focus is, then, to advance the existing Semitic derivation morphology research a step further. It is to design a generic approach that synthesizes words from roots using rules, cluster POS variants and POS-homogeneous forms of a root; note that POS homogenous clustering is the main organizing principle of WordNet's entries. Generally our approach is novel in that it is the reverse of the lexicon development approaches used in resource-rich languages. For instance, in CatVar or DERIVBASE, the idea is analysis-based generation; mainly relying on pre-existing resources and tools. This limits the accuracy of results due to cascading of preexisting resources limitations into the generated lexicons. Moreover, the use of limited clustering intuitions has resulted in lexicons dominated with singleton members. To overcome this, the intent is to use multiple intuitions and language features. For instance, POS variant clustering can be achieved using multiple, hierarchical heuristic insights. For instance, integrating root signature for each derived-form produces at-least one macro-cluster with multiple elements. Given, a macro-cluster, integrating alternative, possibly multiple intuitions can result in more coherent subclusters. One of the intuitions can be setting the threshold for sub-cluster members to be a minimum of two; otherwise, the candidates for sub-clustering remain to be members of the macro-cluster. Unlike POS-variants, POS-homogenous clustering is mostly achievable with linguistic rules and hence is anticipated to be handled as such. Features for both POSvariant and POS-homogenous clustering can be captured at the time of derivation.

Our approach has five steps, as represented in (Fig. 1). Fig. 1: High-level architecture to design derivation lexicon for Semitic languages We now illustrate our design highlighting on important points. Implementation of the approach is based on Amharic, the second widely spoken Semitic language. Our intent is rule-based stem and surface form synthesis. Rules from text books [START_REF] Baye | የአማርኛ ስዋሰው:የተሻሻለ ሶስተኛ እትም. 3rd edn[END_REF]Bender and Fulas, 1978) and the root corpus (around 1280) of Bender and Fulas(1978) are considered. Our design excludes simple nouns (e.g., semay: ‗sky'), adjectives (qey: ‗red'') and adverbs. Instead, it focuses on verbs, de-verbal nouns and adjectives which take up the lion share of these languages' vocabularies. Rule implementation is based on regular expressions or finite states in general. Noise filtering considers the use of corpora and prediction technique. The clustering step has two components: cluster POS-variants and POS-homogenous forms. Given the labeling of each POS variant with multiple features (e.g., type of verb, noun and adjective) at the derivation phase, it is possible to have a more effective POS-variant clustering approach. For instacne, one clustering parameter can be to consider the extent to which the noun and adjective forms are semantically linked with the respective verb form. Table 1 shows that cluster 1 is about someone, while cluster 2 is about an ‗object'. On the other hand, POS-homogenous clustering (see Table 2) allows having intra-POS clusters for nouns, verbs and adjectives of a root. This can be handled using rules from [START_REF] Baye | የአማርኛ ስዋሰው:የተሻሻለ ሶስተኛ እትም. 3rd edn[END_REF]. This illustration is based on examples from the Amharic 15 language.

Conclusion and Future Work

In this paper an attempt is made not only to thoroughly survey the literature and justify the need for a novel approach to design derivation lexicon for Semitic languages but also presented illustrated design architecture. In this regard, the concept of FSA in its various forms are relevant in realizing the very early stages of our approach such as in generating surface forms from roots, patterns, vocalism/vowels and rules. We also benefit by using noise filtering strategy. Finally, we also experiment on using a small seed data based word prediction algorithm. However, the later stages such as forming POS-variant derivational clusters and the POS-homogenous clusters require innovate solutions, amounting to important new contributions to the NLP and IR research. It is important to note that the major contribution of this paper is a thorough survey of the literature and illustrated design architecture. 15 The morphological rules are taken from [START_REF] Baye | የአማርኛ ስዋሰው:የተሻሻለ ሶስተኛ እትም. 3rd edn[END_REF] and English glosses are mainly from Amsalu (1987) and Kane (1990) Amharic-English Dictionaries

Table 1 .

 1 POS-variant cluster example of the root ‗s-b-r', referring to -break‖

	Cluster Verb	Noun	Adjective
	1	sebber-e: ‗broke, broke-in'	sebar-i: ‗one who breaks'	sebber: ‗defiant'
	2			te-sebbar-i: ‗fragile',
		te-sebber-e: ‗was broken'	sIbbar-i: ‗fragment'	sebar-a: ‗broken'

Table 2 .

 2 POS-homogenous cluster examples (nouns)

	Process: Cluster-1	Object: Cluster-2	State/condition: Cluster-3
	seber-a: ‗act of breaking'	sebar-a: ‗broken piece'	sIbbIrat: ‗fracture'
	sIbr-iya: ‗process of breaking'	sIbbari: ‗fragment'	sIbr: ‗feeling of strain/hunger'

https://clipdemos.umiacs.umd.edu/catvar/, last accessed

2021/12/03.[START_REF] Aqel | Building an Arabic Word Generator[END_REF] Link-ability[START_REF] Habash | A Categorical Variation Database for English[END_REF] is the percentage of word-to-word links resulting from a specific source.

Romanization is based on: The System for Ethiopic Representation in ASCII by Yitna Firdyiwok and Daniel Yacob(1997).

https://www.memrise.com/course/110178/1500-arabic-verbs-by-frequency/, last accessed on 2021/03/01

https://www.hebrew4christians.com/Grammar/Unit_Ten/Introduction/introduction.html, last accessed 2021/03/04

‗s-l' is not in a root corpus of[5, p.111]; instead there is ‗sll': gloss ‗be paralyzed'.

Amharic-English Dictionary by Kane (1990), Vol.1, pp.2249.

https://www.cs.waikato.ac.nz/ml/weka/, last accessed 2021/03/01

MADA-stands for Morphological Analysis and Disambiguation for Dialectical Arabic

E.C. stands for Ethiopian Calendar, which is 7 years (September to December)/ 8 years (January to August) behind from the Gregorian calendar.


Marta Donazzan

Clémentine Raffy

Bridget Copley

Klaus Von Heusinger

Letting structure speak with authority: Constraining agents' choices with French laisser

Letting structure speak with authority: constraining agents' choices with French laisser

Introduction

The French verb laisser 'let' is well-known for being peculiar among causative verbs in Romance, as it licenses two different embedded clauses. The sentence in (1) exemplifies the so-called infinitive construction, where laisser embeds an infinitive clause with a preverbal subject; in (2), the verb enters a complex predicate construction, which has received different analyses in the literature [START_REF] Alsina | On the argument structure of causatives[END_REF][START_REF] Guasti | Semantic Restrictions in Romance Causatives and the Incorporation Approach[END_REF][START_REF] Folli | Causation, obligation, and argument structure: On the nature of little v[END_REF]. In this construction, the understood subject of the infinitive verb is realised postverbally, or, in the case of transitive verbs, as the complement of a preposition.1

(1) Jean a laissé les enfants manger. John laisser.PF the children eat.INF 'John let the children eat.'

(2) Jean a laissé manger les enfants. John laisser.PF eat.INF the children 'John let the children eat.'

The first question that arises with regards to (1) and ( 2) concerns the relation between form and meaning. It has been observed very early on [START_REF] Borel | Sémantique des factitives en français[END_REF][START_REF] Kayne | French Syntax: The Transformational Cycle[END_REF]) that the two structures in (1) and (2) are correlated with two slightly different interpretations, but this intuition has been developed quite informally, and judgements are therefore not consistent in the literature, where the interpretive difference has been described as, at best, pragmatic effect [START_REF] Abeillé | Les causatives en français, un cas de compétition syntaxique[END_REF]. We believe however that the relation between form and meaning deserves a more careful investigation, since differences in meaning can reflect differences in structure particularly in the case of causative constructions, where distinct interpretations correspond to different causative relations that are conceptualised in different ways. The link between syntax and conceptual structure is given by grammar, to the extent that grammar determines the way in which the participants in a causal relation are realised as the arguments of a causative predicate. As it has been extensively discussed in the literature (see e.g. [START_REF] Shibatani | The grammar of causative constructions: A conspectus[END_REF]) the grammars of different languages deal with conceptual structure in different ways, and there may be alternative ways of realising causal chains even within one particular language. One of the most famous examples is probably the distinction between direct and indirect causation as expressed by lexical (3a) vs. analytical constructions (3b) in English (Fodor 1970). It is generally assumed that the lexical causative verb kill in English expresses a relation of direct causation, i.e. in (3a) John did something that directly led to the death of Bill. Causative constructions like cause to die in (3b), on the other hand, may also express a more indirect relation: John might have done something which started a longer causative chain leading, at the end, to the death of Bill (but see [START_REF] Neeleman | The Linguistic Expression of Causation[END_REF] for arguments against this generalisation).

(3) a. John killed Bill.

b. John caused Bill to die.

It is thus fairly reasonable to assume that the grammatical constructions in ( 1) and ( 2) may each realise a distinct causative relation.

In the specific case of ( 1) and ( 2), however, probing the issue of form and meaning leads to a related question, which is the main focus of this paper. Following the intuitions of native speakers, also reported in previous literature, the two interpretations can be paraphrased as such: while (1) can only convey that Jean had the intention to let the children eat, (2) seems to be also compatible with a scenario in which Jean is less directly responsible for their action, and merely failed to prevent them from eating. Looking at the interpretations, then, one may wonder: how are concepts such as intentions and causal responsibility expressed in language, or, more specifically, to what extent does grammar "see" intentions and map them into syntactic structures? The question is vast and goes far beyond grammatical analysis; we shall be satisfied if we manage to take a few steps towards an answer.

In this paper, we show that the analysis of laisser may help us do so. To start with, we show that the distinct interpretations of the laisser constructions in ( 1) and ( 2) can be probed by looking at the particular type of influence that the subject of laisser (the Causer) exerts on the subject of the infinitive (the Causee). More specifically, in (1), but not in (2), this influence must be that of authority: sentence (1) represents a state of affairs that is compatible with a situation where John allows the children to eat by virtue of his position of authority -in other words, John authorises them to eat. This is not necessarily the case in (2), which is compatible with a situation where the children started to eat without being granted permission, and John merely did not intervene. The link between form and structure is intuitively the following: since authority can arguably be exerted only by intentional agents on intentional agents, and agentive thematic positions are constrained by grammar across languages, one can predict that authority-related interpretations may also be restricted to specific syntactic structures, i.e. the ones where the two participants are both mapped onto agentive positions. We claim that this is what determines the structural difference in the two French sentences. Evidence from French may in this sense support the hypothesis that the link between form and meaning in causative constructions is expressed at the interface of syntax with the semantic component of grammar. The exact implementation of the syntactic module goes beyond the scope of this paper, and we must leave it to further research. The paper is organised as follows. In section 2, we expound the theoretical assumptions that form the background of our analysis of the interpretation of causal relations as conceptual configurations. We draw these assumptions from recent approaches to the use of forcedynamic representations for meaning, as first proposed by [START_REF] Talmy | How language structures space[END_REF][START_REF] Talmy | Force dynamics in language and cognition[END_REF][START_REF] Talmy | Toward a cognitive semantics: Typology and process in concept structuring[END_REF], developed by [START_REF] Wolff | Direct causation in the linguistic coding and individuation of causal events[END_REF][START_REF] Wolff | Representing causation[END_REF], and further elaborated at the interface with linguistics by [START_REF] Copley | A force-theoretic framework for event structure[END_REF]. In section 3, we discuss more specifically the formal representations of agency and authority in such configurations, and we come back to the case of laisser in section 4, where we show that looking at authority and intentions provides a solution to the interpretation issue raised above. Section 5 concludes.

Theoretical background

Causal configurations in force theory

Cognitive linguist Leonard Talmy first brought linguistic attention to the usefulness of forcedynamic representations for natural language semantics [START_REF] Talmy | Force dynamics in language and cognition[END_REF](Talmy , 2000, e., e.g.; see also [START_REF] Copley | Force dynamics[END_REF] for an overview). The idea we are interested in here is the grounding of the concept of causation in people's cognitive representations, focussing in particular on the representation of forces and their interactions in space (Wolff & Thorstad 2016). We follow Wolff andSong 2003, Wolff 2007 in specifying how the concept of CAUSE, a primitive operator in lexical and syntactic decompositional approaches (see, a.o., [START_REF] Dowty | Word Meaning and Montague Grammar. The semantics of verbs and times in gener-ative semantics and in Montague's PTQ[END_REF][START_REF] Hale | On argument structure and the lexical expression of syntactic relations[END_REF][START_REF] Ramchand | Verb meaning and the lexicon: A first-phase syntax[END_REF], may be deconstructed into finer elements, and how these elements can be represented in a formal system interacting with grammar. In this section, we will start by reviewing the basic configurations predicted by Wolff and Song's theory, and give a quick review of the configurations that possibly underlie the meaning of different causative verbs. With this in mind, we will then be able to show how laisser, as a particular type of causative operator, may help us refine the set of primitives needed in structural representations of causation.

A causal configuration, for Wolff and Song, implies the interaction of an Agent and a Patient, represented as vector forces of given magnitude directed towards a goal. This type of conceptual representation gives origin, at the level of individual configurations of forces, to three main causal concepts: CAUSE, ENABLE (which includes ALLOW and HELP) and PREVENT. The three concepts can be differentiated via three parameters, as detailed in Table 1: (i) the tendency of the Patient towards the goal -that is, whether the Patient's force is directed towards the endstate prior to the intervention of the Agent; (ii) the relationship between the tendencies of Agent or Patient -whether the two participants in the causal relation are both directed towards the goal or not; and (iii) the direction of the configuration -whether the goal is indeed targeted as the result of the interaction of the Agent's and Patient's forces. The dynamics of CAUSE, ENABLE and PREVENT can be represented as configuration of forces as in, respectively, Figures 1a, 1b and 1c, where the vector A represents the force associated with the Agent, P the force associated with the Patient, and R represents the position of the Patient as a result of their interaction. One of the consequences of representing causal relations in vector space as in Figure 1 is that the goal does not need to be reached in order for a causal interaction to occur -the occurrence of the goal endstate depends on the magnitude and direction of the resultant vector. Therefore, according to the theory, one may predict that only CAUSE and ENABLE configurations are compatible with the actual occurrence of the goal endstate (since in the PREVENT configuration the R vector is not directed towards the goal), but the occurrence of one of these two causal configurations does not guarantee by itself that the goal occurs. As we will see, this prediction is borne out in the case of laisser, which realises a particular case of the ENABLE configuration.

Types of influences

The framework of this force-dynamic theory, in defining at least three possible causal configurations, also makes room for the hypothesis that the type of force interaction between Causer and Causee may correlate with the choice of different causative verbs lexicalising the relation. In the following, we would like to submit that lexicalisation may depend not only, more broadly, on the type of configuration (thus differentiating, in English, between the CAUSE, ENABLE and PREVENT configurations and the homonymous verbal predicates), but it can also be sensitive, more specifically, to some of the parameters that determine such configurations. One of these parameters, which we wish to discuss in detail, has to do with the type of influence that the Causer exerts on the Causee. Throughout this paper, we use the term "influence" as a porte-manteau for different types of forces, starting from Talmy's observation that Causers can indeed exert pressure of various kinds: besides physical forces, intentions and social or psychological pressures can also influence the progression of an event towards an endstate (cf. [START_REF] Wolff | Representing causation[END_REF]).

In the case of LET verbs such as laisser, the type of influence is necessarily an intention. configurations in French, such as permettre 'allow'. The subject of permettre can exert either a psychological or a physical influence on the Causee. Accordingly, the sentence in (4a) may be interpreted in both ways: (4a) could mean that Marie authorised Julie to go out with her friends, or that, for example, she helped her climb out of a hole by joining her physical strength to hers. Authority cannot be at stake in (4b), where the wind enables the windmills to turn by exerting a purely physical force against their blades.

(4) a. Marie a permis à Julie de sortir. Marie allow.PF to Julie to go-out 'Marie allowed Julie to go out/ Marie helped Julie go out.' b.

Le vent a permis aux éoliennes de tourner. the wind allow.PF to-the windmills to turn 'The wind allowed the windmills to turn.' Laisser could be compared to permettre in its interpretation of authorisation in sentence (5a); however, (5a) lacks the second possible interpretation of (4a), where Marie would help Julie out of a hole. The fact that in the case of laisser the influence can only be an intention is also confirmed by the infelicity of (5b).

(5) a. Marie a laissé Julie sortir. Marie allow.PF Julie go-out 'Marie let Julie go out.' b.

#Le vent a laissé les éoliennes tourner. the wind laisser.PF the windmills turn We will see that intention must characterise both Causer and Causee when it takes the form of an authorisation from the Causer, as in (5a). This leaves us with the issue of characterising the role of the Causee as an intentional Agent. We discuss this point in the next section, where we provide the first sketch of a formal representation of agency in causative structures.

Characterising authority as a constraint on choice

We have seen that Marie in (5a) exerts a particular influence through an intentional act (an act that Marie performs because of her intention). Our aim in this section is to define more precisely the conceptual status of influences based on intention, and more specifically of the influence exerted by authority, and its effect within a causal chain. In accordance with our

The existence of a few idiosyncratic inanimate exceptions here meets Copley's (2018) criterion for "dispositional causation", where intentions are understood as a species of disposition. The felicitous cases such as (i) might then be seen as involving a disposition of the subject that causes an event of the kind described by the complement, whereas those that do not admit laisser should be seen as describing impossible courses of events, where there is no such disposition of the subject that can cause an event of the kind described by the complement. See also [START_REF] Donazzan | Dispositions in event nouns : decomposing the agentivity constraint[END_REF], who make a similar case for dispositions licensing a causative entailment in light-verb constructions.

assumption that there exists a link between conceptual representations and language realisations, we will try to represent it in the grammatical structure by making use of tools provided by a formal framework.

Agency as choice

Given that, as we have seen in the preceding section, authority is an influence exerted by agents, we start by providing a more general definition of agency. Along with standard philosophical literature [START_REF] Anscombe | Intention. Proceedings of the Aristotelian Society[END_REF], we assume that agents have intentions when their action is directed towards a goal. We may then represent an intentional action as an influence that is directed towards the occurrence of a particular state of affairs, which we represent formally as a proposition. What is important for our present concern is the observation that, when their will is unimpeded, agents have the choice of pursuing different goals. Following our initial assumption, then, these different goals will be represented as a set of alternative propositions. The signature of free agents is then that they have a choice over an ALT set of alternative propositions. Let's consider some examples. A sentence like (6) below is understood as depicting a situation where John's actions or will are directed towards realising a state of affairs in which he plays the piano. Accordingly, let's assume that the goal of John may be represented by the proposition embedded under the predicate of intention. Alternative propositions are denoted, in linguistic expressions, by (non-tensed) clauses [START_REF] Rooth | A theory of focus interpretation[END_REF]). Once the co-reference of the subject under the control configuration has been resolved, we may assume that the embedded clause in (6) denotes the proposition p = John play the piano. Since John is the holder of an intention and therefore an intentional agent, in principle he has the choice whether to pursue this goal or not: his choice includes a set of propositions alternative to p. In the absence of prominent focus on one of the elements in the embedded clause, 3 we take this set of alternatives to be the verum focus set of alternatives, namely p and ¬p. We represent alternative propositions as belonging to the set ALT, which minimally includes the proposition p expressed by the infinitive predicate (the prevalent) and a proposition ¬p, which is intended as a negation of the prevalent p (John play the piano).

The set of alternative states of affairs available to John may thus include other states of affairs, but the main predicate of the sentence states that John himself has restricted his choice to one possible alternative, that of playing the piano. In this sense, the matrix predicate, in complex constructions, determines how the ALT set is dealt with. As shown by the second conjunct in (7b), when the main predicate is not a causative verb or a modal operator, John, as a free agent, can choose to follow any other alternative goal which may be available to him.

(7) a. We asked John [to play the piano] ALT JOHN := {p, ¬p} b. We asked John to play the piano, but he watched TV instead.

Within a causal configuration, then, an influence affects the available choices of a free agent with respect to the actions in service of their goal(s). What happens when an influence is exerted by a free agent on another free agent, as in complex causative structures? More specifically, to what extent does the influence lexicalised by a specific causative predicate constrain the choices available to an agentive Causee?

Constraining agency in complex causatives

The result of an influence can be conceived as the Causer's preference for one choice -that is, one course of action -among alternative options [START_REF] Staraki | Necessity, intention, and causation: from force interaction to eliminating the causative entailments[END_REF]). Let's consider, for instance, sentence (8). In (8), contrary to (7) above, John's alternatives are reduced, and this follows from the influence exerted by Peter -John may want to play the piano or not, but Peter leaves him with no choice by setting the value of the ALT set to one possible state of affairs, represented by p. Therefore, adding the second conjunct in (8b) yields an infelicitous sentence.

(8) a. Peter forced John to play the piano.

ALT JOHN := {p, ¬p} Peter sets value of ALT JOHN := {p} b. #Peter forced John to play the piano, but John didn't (play the piano).

In the semantic representation of causative constructions, we therefore model the influence required by the causative verb as the ability to constrain in different ways the set of alternative actions available to the lower agent (the Causee). Sentences ( 9) and ( 10 therefore, all possible choices are granted. In (10), the influence of the Causer is directed against the Causee's tendency, and therefore the value of ALT is set to {¬p}. So much for the different configurations. However, we have seen that influences can be of different types, and that we may assume, following a lexicalisation hypothesis, that certain causative predicates impose constraints on the nature of the relevant influence. For example, the English verb forbid in ( 11) is a predicate that, as a causative predicate of the PREVENT type, requires the Causer to exert an influence on the Causee. Contrary to prevent, however, forbid requires two agentive arguments, and imposes additional constraints on the type of influence exerted by the Causer. More specifically, the proposition realised by ( 11) is felicitous only in a situation where God may exert a type of authority over Adam: Adam may want to eat the apple or not, but God, who has authority over him, sets the value of Adam's alternative set to {¬p}. Crucially, however, as is well-known given the actual outcome, it is still acceptable for the Causee in (11) to overcome the Causer's influence and exercise his free will.

(11) God forbade Adam to eat the apple (but Adam did eat the apple).

Authority is then a type of coercive intention that acts as a force constraining an intentional agent's choice of action. Contrary to physical force, however, authority is not strictly implicative (the free agent may still have a choice) and is legitimate only if the two agents are in a social or contextual relation that justifies the influence itself. 4 In case of mismatch in the presupposed authority relation, verbs of influence such as forbid are infelicitous, cf. (12a) vs. (12b).

(12) a. The judge forbade the defendant to speak. b. #The defendant forbade the judge to speak.

When syntax matters: structural constraints on authority relations

The French causative verb laisser 'let' is generally described as realizing an ENABLE relation (as defined in Wolff & Song 2003, cf. Table 1). As we have seen in section 1, contrary to other ENABLE verbs such as English let, laisser can embed its complement clause in two ways. Unlike their English translation, then, the two structures, exemplified here by ( 13a) and (13b), are said to correlate with two interpretations [START_REF] Borel | Sémantique des factitives en français[END_REF][START_REF] Kayne | French Syntax: The Transformational Cycle[END_REF]).

(13) a. Le gardien a laissé le prisonnier s'échapper. Pre-V Causee the guard laisser.PF the prisoner CL-escape 'The guard let the prisoner escape.' b. Le gardien a laissé s'échapper le prisonnier.

Post-V Causee the guard laisser.PF CL-escape the prisoner 'The guard let the prisoner escape.' Discussing specifically the examples in (13), Kayne (1975: 222) remarks that the structure (13a), where the Causee is realised preverbally, can be interpreted as a situation where the guard acted with "complicity" or "deliberate neglect" with respect to the prisoner's attempt to escape, while there is no such inference in (13b). In other words, we may say that (13a) carries an intentional flavour: it seems to be the guard's intention to give the prisoner the choice to escape. Following our analysis, then, only (13a) implies an influence that can be characterised as an intention. But how does this conceptual interpretation correlate with the structural difference between the two sentences? And what is the influence exerted by the guard in (13b)?

In the following, we will address this question by looking at the constraints on interpretation imposed on both the pre-V and the post-V constructions. For the sake of clarity, we will set up a context where the two participants are quite uncontroversially in an authority relation. We take as a prototypical case, among other possibilities, the relation of a judge and a defendant in court, assuming that the authority of the judge is recognised and enforced by the law. Also, in order to highlight the desired interpretations, we will make use of specific contextual conditions: if the Causer authorises the Causee to act, we may expect that the Causee's action will necessarily start after the authorisation is granted. Conversely, if the Causer merely does not interfere with the Causee's action, it may be possible that their action is already going on, and the Causer just refrains from intervening.

Authority and preverbal Causee

As we have seen in the preceding section, we may characterise authority relations as implying the presence of two intentional agents, one of which, the Causer, performs an intentional act that constrains the choice of action available to the Causee. With this in mind, let's consider sentence ( 14). ( 14) La salle d'audience était silencieuse. Finalement... The courtroom was silent. Eventually... La juge a laissé l'accusé the judge laisser.PF the-defendant 'The judge let the defendant speak.'

The context for sentence (14) enhances the authority reading -the judge has authority on the defendant, and the defendant's action, as evidenced by the preceding sentence, is due to start only after the authorisation has been granted. More importantly, we predict that the sentence should only be compatible with a situation where the Causer is in a position of authority with respect to the Causee: similarly to the forbid case discussed with respect to example (12), we expect such structures to be infelicitous if the higher Agent has no authority over the lower one. This prediction is borne out: sentence (15), which, if we are correct, displays a mismatch in the authority relation, is considered unnatural or degraded in a prototypical courtroom context by most of the native speakers we have consulted. We claim that post-V constructions like (18) do not necessarily make reference to an authority relation and thus do not trigger the interpretation of the Causer as an influencer. Since the relation is not one of authority, we predict that no mismatch in authority can ever arise; indeed, native speakers' judgements confirm this prediction, as ( 19) is judged more acceptable in a normal courtroom situation than (15) above. In postverbal constructions, the lower subject is not interpreted as an external argument of the embedded verb, it is not realised as an agentive subject, and therefore no ALT set is introduced. In some sense, the sentence may be interpreted as a case of enabling by omission: i.e. as describing a situation where the higher agent does not exert any influence in order to restrict the lower subject's action. Although the exact characterisation of the syntactic structure of pre-V and post-V constructions is beyond the scope of this paper, the pre-or post-V position of the embedded subject may be correlated to distinct realisations of the argument structure of the embedded predicate. Following standard assumptions in the literature [START_REF] Kratzer | Severing the external argument from its verb[END_REF][START_REF] Harley | External arguments and the Mirror Principle: On the distinctness of Voice and v[END_REF], Alexiadou et al. 2015, a.o.), we may suppose that the agentive subject of the infinitive is introduced as the specifier of a dedicated functional projection, such as VoiceP (20a), of which, following our analysis, we would give the tentative denotation in (20a). The post-V complement, on the other hand, would be a vP without external argument position (20b).

(20) a.

Preverbal case complement :

[[VoiceP]] = λs.chooser(x ,s,ALT ([[vP]])) & agent(x,e) & [[vP]](e) b.
Postverbal case complement :

[[VP]] = λe.[[VP]](e)
What ultimately happens to these denotations in the syntactic derivation may be more complex and is beyond the scope of this paper. In the following section, we will discuss some additional empirical data that may confirm our semantic hypothesis.

Additional evidence for the analysis

We have shown that the two available readings for laisser are enhanced from structural constraints. The authorise interpretation is constrained by the possibility of constructing a sentence where the lower agent is interpreted also structurally as the agent of the embedded verb: in pre-V constructions, laisser embeds a clause whose subject is interpreted as an external argument, i.e. an agent (possibly by a VoiceP) -the embedded clause denotes then a proposition in the set of the agent's alternatives.

In Post-V constructions, on the other hand, laisser embeds a reduced vP, with no external argument. The interpretation is that of an event description, and not of a propositional complement qualifying as an alternative choice.

But to what extent does grammar see conceptual objects such as alternative propositions?

In this section, we present a few empirical observations pointing to the conclusion that alternatives indeed enter the semantic component which is processed by grammar. More specifically, following our analysis we expect at least two types of structural correlates, related to: (i) the complement of laisser: whether it is a propositional or a non-propositional complement; (ii) the presence vs. absence of available alternatives for the lower agent. In this section we mention two phenomena that seem to depend on a sensitivity to these two parameters.

Negation

The first observed empirical difference between preverbal and postverbal constructions has to do with the possibility of embedding a negative operator in the former case. Assuming that alternatives are propositional in preverbal constructions, we expect that a negative operator can apply to the complement of laisser in this construction. Indeed, under an authorise reading the causative verb can embed a clausal negation. Sentence (21a) is to be understood in a context where the judge authorises the defendant to answer a question; in the same courtroom situation, (21b) is perfectly acceptable if the defendant expresses the intention not to answer the question, and the judge authorises him to do so.

(21) a. La juge a laissé l'accusé répondre. the judge laisser.PF the-defendant answer 'The judge let the defendant answer.' b. La juge a laissé l'accusé ne pas répondre. the judge laisser.PF the-defendant NEG answer 'The judge let the defendant not answer.' Conversely, we assume that event descriptions are not propositional, and therefore we expect that the complement of laisser cannot host a negative operator in postverbal constructions. Thus, while (22a) is compatible with a context where the judge does not impede the defendant from answering, (22b) is ill-formed. The ill-formedness of (22b) can be explained both on structural and semantic grounds: the syntactic constraint would say that the clausal negation ne pas cannot be expressed in a reduced vP structure, but one can also argue that there is no sense in which the judge could interrupt the occurrence of a non-event.

Agency as choice: defeasability of causative entailments and free choice

Recall that the main difference between preverbal and postverbal constructions concerns the possibility for the lower agent to have a choice over a set of alternatives in the former case: in preverbal constructions, the agentive subject of laisser allows the lower agent to keep all the alternatives in their choice set available ( 23).

(23) a. La juge a laissé l'accusé parler. the judge laisser.PF the-defendant speak b. Judge sets the value of ALT defendant := {speak, not speak} In this framework, an influence such as that exerted by the subject of the matrix verb can be conceived as guiding the preference for one choice among the alternative options within the set (see also section 3.2 above). The lack of constraints observed in the complement of laisser in (23) can then be formalised in terms of an indifference relation among the propositions in the ALT set (see e.g. Staraki 2017 for a formal implementation of indifference in a possible-world semantics). In plain words, indifference means that the two propositions p and not-p are not ranked in terms of preference with respect to one another, because the subject of laisser, who exerts the influence, chooses not to posit any ordering on them. If we are right, we therefore expect that an indifference relation among alternatives in the complement of laisser may be observed only when the subject of laisser is an intentional agent, who can choose not to rank the alternatives; also, a preference choice over the alternatives is expected to depend on the ability of the lower subject, as an intentional agent, to make a choice. Next, we may also expect that the presence of an alternative set may trigger the use of lexical or functional items sensitive to semantic environments that denote choice over possible alternative worlds or propositions. In the following, we will provide two sets of empirical observations that confirm our expectations.

The first observation concerns the (non-)implicative interpretation of causal relations. We have seen in section 2.1 that [START_REF] Wolff | Models of causation and the semantics of causal verbs[END_REF] taxonomy of causal categories predicts that the causative meaning of laisser as an ENABLE verb is non-implicative: the endstate represents a tendency, and it is envisaged once the direction of the resultant vector is defined. It "does not require that the result event occur before it can be said that causation has occurred" (Wolff & Thorstad 2016: 150, and also Table 1), and implicative readings, by which the endstate is asserted to occur, would rely on an independent dimension, which is given in this framework by the length of the endstate vector. This conceptual representation agrees with the observation that authorise readings of laisser are non-implicative, in the sense that the endstate need not be reached for the laissersentence to be felicitous. Thus, the continuation in (24b) is not considered a contradictory statement, but it may be analysed as the cancellation of an implicature arising from the expectation that Causees follow their tendency in acting.

(24) a. La juge a laissé l'accusé parler… the judge laisser.PF the-defendant speak… b. …mais finalement il est resté silencieux. but eventually he stay.PF silent 'The judge let the defendant speak, but eventually he kept silent.'

In the framework adopted in this paper, the non-implicativity of ENABLE verbs can be translated by saying that the matrix subject of laisser does indeed exert an influence (therefore, causation occurs), but lower agents, despite having a tendency towards the endstate denoted by the prevalent p, still keep all the alternatives p and not-p in their choice set available. The defeasibility of the causative entailment for ENABLE-verbs is thus compatible with the configuration given in Force Theory. We take a step further in this paper and claim that there is also a grammatical dimension to this cognitive representation. On the semantic side, the defeasibility of the entailment that the endstate has been reached is observed only when the causative relation involves two agentive participants. Thus, in sentences ( 25) and ( 26), where either one of the Causer and Causee is non-agentive, asserting that the endstate has not been reached yields a contradiction. 2014) defeasible causation). Here we use the label "defeasible entailment" in a descriptive way, without strong commitment to a specific analysis; note however that the correlation between agentivity and defeasibility is expected in our framework, since only agentive subjects can choose not to impose an ordering between the alternatives. What is more interesting for our present concern is that defeasibility is also subject to a structural condition with laisser: the causative entailment appears to be nondefeasible when laisser embeds a vP complement in the postverbal construction, and this happens independently of the agentive potential of the lower agent. In ( 27), the judge can be considered, categorically speaking, an animate entity who is potentially volitional; nevertheless, contrary to (23b), the continuation in (27b) is considered degraded by most speakers.

(27) a. L'accusé a laissé parler la juge… the-defendant laisser.PF speak the judge b. ??mais finalement elle est restée silencieuse. but eventually she stay.PF silent ('The defendant let the judge speak, but eventually she kept silent.') Once again, to our mind, the reason why the entailment is not defeasible in ( 27) has to do with the type of complement that laisser embeds in this construction. In ( 27), the defendant does not give the judge the choice to speak, but merely does not prevent an event from occurring. Additionally, there is flavour that the action has already started: sentence (27a) is considered odd by native speakers in a context where an inceptive interpretation is forced on the embedded event, as in (28).

(28) La salle d'audience était silencieuse.

The courtroom was silent. #Finalement, l'accusé a laissé parler la juge eventually the-defendant laisser.PF speak the judge Next, let's mention a further empirical fact that follows from the assumption that authoriselaisser involves quantification over an alternative set: only in these constructions are certain free-choice items licensed in the embedded clause. Recall that the subject of laisser, in virtue of her position of authority, offers a choice to the lower agent by choosing not to order the alternatives in the ALT set in terms of preference with respect to one another (an indifference relation).

The presence of non-ranked available alternatives seems to be relevant for licensing Free Choice Items (FCIs) like the French determiner n'importe qu-'(just) any', which has been described as conveying a meaning of indiscriminacy [START_REF] Jayez | Free choiceness and non-individuation[END_REF][START_REF] Vlachou | Definite and indefinite free choice items: Evidence from English, Greek and French[END_REF], 2007).

(29) Le passager a laissé le conducteur prendre the passenger laisser.PF the driver take n'importe quel itinéraire pourvu que ce soit rapide. n'importe quel route provided that it be.SBJ fast 'The passenger let the driver take any route, provided it would be a fast one.' According to Vlachou (2007:52) "indiscriminacy implies that an agent makes a choice in such a way that, before choosing, any alternative is equally probable to be chosen", and results in a "random selection by an agent of an entity out of a set of alternatives" (2007:131). In complex causatives, indiscriminacy would be the result of the Causer's choice to keep all alternatives equally ranked in terms of accessibility for the lower agent in the embedded clause. The fact that the lower agent does not seem to randomly choose an option would then be imputable to the meaning of laisser, which, as an ENABLE verb, conveys the meaning that there is a tendency of the Causee towards the prevalent p.

FCIs such as n'importe qu-are more generally not available in configurations where the lower agent's choice is already constrained from the causative meaning of the matrix verb, as in the case of forcer 'force' in (30).

(30) #Le passager a forcé le conducteur à prendre the passenger force.PF the driver to take n'importe quel itinéraire pourvu que ce soit rapide. n'importe quel route provided that it be.SBJ fast 'The passenger forced the driver to take any route, provided it would be a fast one.' Although the issue of the licensing of FCI is a complex one, and its detailed discussion goes far beyond the scope of this paper, we believe that the contrast observed between ( 29) and (30) can in principle be explained assuming that lexical causative verbs constrain the set of alternatives denoted by their complement in different ways.

Conclusions

An agent's actions and intentions can be furthered or hindered in multiple ways. Across languages, verbs that lexicalize causative primitives can help us understand the nature of agency and intention, precisely because they involve multiple participants which may be in a position of influencing each other via different types of force relations. In causal relations, free choice can be restricted (or highlighted) through authority: we define authority as an agent's intrinsic ability to influence another agent's choice of action. The goal here was to probe the relation between authority and intentional causation by looking at a construction where the causative verb expresses an ENABLE relation (Wolff andSong 2003, Wolff 2007) between agentive participants. We have shown that authority relations are visible in grammar: authority is possible only when both participants are mapped as agents in the structure, reversing authority relations with laisser is not felicitous in the cases where authority is relevant, as we have seen in the authorise scenarios with the pre-V structure for laisser.

Figure 1 :

 1 Figure 1: the dynamics of (a) CAUSE, (b) ENABLE and (c) PREVENT

  intends to play the piano. b. John intend [John play the piano] c.ALT JOHN := {play the piano,¬ play the piano}

  let the judge speak.'

Table 1

 1

	: Representation of causal concepts (adapted from Wolff & Song 2003:284)
		Tendency of the	Opposition of Agent	Occurrence of the
		patient for the result	and Patient	result
	CAUSE	no	yes	yes
	ENABLE	yes	no	yes
	PREVENT	yes	yes	no

  ) below represent causative configuration of the ENABLE and PREVENT type, respectively.

	(9)	Lucy allowed Peter to go out tonight.
		ALT PETER {go out, not go out}
		Lucy sets value of ALT PETER := {go out, not go out}
	(10) John prevented Mark from watching TV.
		ALT MARK {watch TV, not watch TV}
		John sets value of ALT

MARK := {not watch TV}

The representation in (9) captures the intuition that the Causer in ENABLE configurations exerts an influence that is in accordance with the tendency of the Causee (see also Table

1

);

Causation by omission: postverbal Causee Let

  How is this interpretation related to the syntactic structure of the sentence? According to the representation that we have adopted so far, the verb laisser embeds a proposition realised by the non-tensed predicate parler 'speak'. The Causee is as the agentive subject of the embedded verb, i.e. the lower Agent of the causal relation. The lower Agent, being an intentional subject, introduces in the formal representation an ALT set (16b) whose members are the prevalent p (speak) and its negation ¬p. The meaning of laisser, as a causative verb, is that the higher Agent must be able to restrict the ALT set with authority. Recall however that, if we are right in considering laisser an ENABLE verb, the Causer is acting in accordance with the Causee's tendency, and therefore both alternatives in ALT are made available to the Causee (16c). 's consider now the interpretation of the postverbal construction, exemplified here by (18).

	(15) 4.2 (18) La	La salle d'audience était silencieuse. Finalement... The courtroom was silent. Eventually... ??l'accusé a laissé la juge a laissé parler l'accusé.	juge	5
	the-defendant the judge laisser.PF	laisser.PF speak.INF	the the-defendant judge
	'The judge let the defendant speak.'
						17)
	seems to confirm.
	(17) La	juge a laissé	l'accusé	parler,	mais
	the judge laisser.PF	the-defendant speak.INF but
	est resté	muet.
	remain.PF silent
	'The judge let the defendant speak, but he kept silent.'

(16) a. laisser [ VoiceP the defendant [ vP speak ]] b. ALT defendant := {speak, not speak} c. Judge sets the value of ALT defendant := {speak, not speak}

This prediction is borne out: laisser is not an implicative verb, the fact that the Causee's tendency is directed towards the goal does not imply that the goal is eventually reached. We may qualify the projection of the outcome as an implicature, as the continuation in (

  The relation between the defeasibility of causative entailments and the (agentive) properties of the subject has been already observed in the literature, where this phenomenon has received different analyses under various labels (see a.o.[START_REF] Martin | Explaining the link between agentivity and non-culminating causation[END_REF][START_REF] Martin | The modality of offer and other defeasible causative verbs[END_REF], 2014 analysis of non-culminating entailments and defeasible causative verbs, and Copley & Harley's (

	(25) Sa réponse m'a laissé	comprendre un	certain nombre de
	his answer CL-laisser.PF understand a	certain number of
	choses #mais finalement je	ne	les	ais pas comprises.
	things but	eventually I	NEG CL	understand.PF
	'His answer let me understand quite a few things, #but eventually I did not
	understand them.'
	(26) Jean a laissé	couler	l'eau		dans la	baignoire
	John laisser.PF flow	the-water	in	the	tub
	#mais	finalement l'eau		n'a pas	coulé.
	but	eventually the-water NEG	flow.PF
	'His answer let me understand quite a few things, #but eventually I did not
	understand them. '

For the purpose of this paper, we only will discuss examples where the embedded verb is intransitive. The reader is addressed to the aforementioned literature for more detailed analyses of the syntax of complex predicate constructions in French and in Romance languages.

The authority relation is presupposed, but of course, as in (11) above, it may turn out that the Causer did not have the ability to decide what happens after all; see[START_REF] Copley | The plan's the thing: Deconstructing futurate meanings[END_REF] for discussion of this idea.

Note however that the constraint here is structural, and not lexically enforced as in the case of predicates such as forbid (or authorise), which express authority as part of their meaning. This may be the reason for the difference in acceptability between (12b) and (15) among native speakers, for whom the feeling of infelicity for sentence (15) is weaker than that for sentence (12b), and a context is needed in order to make the contrast more salient.