Appasamy Murugaiyan

TEXT TO MEANING: A FUNCTIONAL PERSPECTIVE *

Describing and understanding an ancient language like Inscriptional Tamil is an enormous challenge in many ways. The most trivial among the difficulties is the relation between the text (form) and meaning. Since the 19th century, there has been a regular paradigm shift in linguistic theory and in the study of languages (from philology to structuralism, generative, functional, etc.). This paradigm shift has provided us with a handful of analytical tools, enabling us to view the discourse (written and spoken) from a new perspective; it has also shown us that texts are more than strings of sentences. These developments, among other things, have put greater emphasis on the social, cognitive, communicative and cultural aspects of language. In this paper, we try to examine the interaction between text architecture, information structure and linguistic devices used. We formulate some hypotheses on the relationship between pragmatics, semantic content (meaning) and structure (syntax), which is crucial in interpreting and extracting information from epigraphic texts. The analysis presented here is based exclusively on a corpus of naṭukal "Hero stone" inscriptions dating between 400 and 650 CE.

INTRODUCTION

Anyone attempting to read Tamil inscriptions, whether accustomed to reading 'Modern Tamil' or not, faces a series of challenges. To test this idea, we sent a sample sentence from the introduction (conventional) part of a Hero stone inscription to twelve Tamil speakers, judiciously avoiding friends and colleagues working on Tamil epigraphy, and requested them to interpret the sentence. We deliberately did not give them any context or background information about the utterance. We received only two responses close to the "meaning". After we revealed the context, however, we got six 'correct' interpretations. This shows that knowing the Tamil language is not in itself sufficient to interpret the text.

The most urgent question used to be, How does one arrive at the meaning of the inscriptions? Some of the exigent issues are -palaeography (different writing systems), lexical items (technical terms and Indo-Aryan borrowings) and, finally, structure and interpretation of the text. Let us say that the hero stone inscriptions describe an event in a particular historical and social setting. We should understand: what the event is about, who the participants are in the event, where and when it happened and be able to decipher a lot of other information contained in the inscription. How are all these types of information manifested in the syntactical structure of Old Tamil? To consider all these questions is beyond the scope of the present paper. In this paper, our main concern will be to capture the relationship between the syntactic structure and meaning of the text. Crucial in this respect is to shed more light on the relationship between discourse units, semantico-pragmatic aspects and syntactic units.

CORPUS

It is important to distinguish between three major types of inscriptions in Tamil. They are (1) Tamil-Brāhmī, (2) Hero stone inscriptions, and (3) Temple inscriptions (including copper plate charts). The present study concentrates only on naṭukal 'Hero Stone' inscriptions. Our corpus consists of texts published in Ceṅkam naṭukaṟkaḷ (Chhs), Dharmapuri kalveṭṭukaḷ (Dha), āvaṇam and Damulica. 1 Our corpus contains 38 inscriptions dating between 0400 and 0650 C E. All these texts are analysed in our 'kalveṭṭu database'. Each text is subject to multi-level top to bottom analysis. We have avoided all damaged, incomplete and doubtful passages in our corpus. The database provides information at different levels: morpheme, word, phrase, clause and sentence. Each text is divided into as many complete and contextually meaningful units (CMU) as possible. This criteria has the advantage, as far as our corpus is concerned, of linking a meaningful unit (propositional content) in a semantic representation to its structural manifestation of syntactic structure. Each lexical and morphological unit is assigned with one or more grammatical information.

Tamil-Brāhmī inscriptions are very short, and each inscription contains hardly more than a sentence with 3 to 10 "words" maximum. The hero stone inscriptions, though still fairly small in size, have a narrative structure with different informational nodes, consisting of one or more complete and contextually meaningful unit(s). Finally the Temple inscriptions are, in contrast, elaborate texts with complex structures. Generally, except in the Tamil-Brāhmī texts, one can identify the following components: (1) Preamble (auspicious formula, eulogy information on the ruling king's name, regnal year, genealogy, and so on); (2) Notification or operational part (details about the donation -the central theme of the inscription); and (3) Conclusion (name of the scribe, witness, benediction and imprecation) (Sircar 1965:126). Each component conveys a different type of information and each type will correspond to a clause or sentence structure. For instance, the information about the king's name and his regnal year is conveyed by a dative-attributive construction; the genealogy, a panegyric poetic genre, includes adjectival, adverbial and verbal causative constructions; the notification (or operational) part of the inscription (description of the donation, donor, recipient, conditions) will contain genitive, locative, dative, transitive, ditransitive constructions; and the last part, the conclusion, will contain hortative constructions. This brief summary will give a general idea of how the text structure, type of information and their formal structure are related to each other.

The language of Tamil inscriptions differs considerably from that of Modern Tamil. For instance, the use of morphological case (accusative, genitive and locative) was not prevalent. Relative participles, adverbial participles and other nominalised verbal forms were used frequently, but finite verbal forms were very scarce. The numeral quantifiers appeared after the noun being qualified. Variation in constituent order is a common feature, and the commonly recognized (canonical) SOV order is one among other possibilities. The constituent order is motivated by pragmatic features rather than syntactic rules.2

CONCEPTUAL FRAMEWORK 1.2.1. EPIGRAPHIC TEXTS AND LINGUISTIC ANALYSIS

The linguistic structure of the epigraphic texts in Tamil and in other Dravidian languages is complex and distinct in comparison to other varieties or genres of texts. For instance, [START_REF] Chandrasekhar | Evolution of Malayalam[END_REF] has proposed an 'actor-action' dichotomy instead of subject predicate structure. Zvelebil, on the structure of Tamil in general, has mentioned very cautiously that neither the traditional syntactic analysis in terms of subject, predicate, object, attributes, etc. nor the immediate constituent (IC) analysis proved to be satisfactory (Zvelebil 1962:151). In a very recent work, [START_REF] Bhat | Grammatical relations[END_REF] questions the universal validity of notions like 'Subject of' and 'Object of', in general and particularly in relation to data from Kannada and Manipuri. Pioneering studies in this direction have made it clear that it is necessary to take into account semantic and communicative dimensions in the description of languages. [START_REF] Kibrik | Beyond subject and object: towards a comprehensive relational typology[END_REF], for instance, in his work on alternative typology has demonstrated clearly that the communicative status: topic/comment, theme/rheme, given/new, focus, empathy, and viewpoint play a crucial role in the grammatical structure.

All these previous observations support our assumption that to adequately handle the structure of inscriptional Tamil we will need a specific and appropriate linguistic tool rather than use the traditional approach in terms subject-object-predicate. In accordance with the recent theoretical developments in language descriptions, we are following a discourse-oriented, functional linguistics framework within which syntax, semantics and pragmatics are essential parameters. The functional approach is sensitive to semantics and pragmatics and focuses on the functions of discourse in communication viewed as a kind of social practice. The aim of the present analysis is obviously to attempt a preliminary investigation into the link between text form, meaning and the (surface manifestation of the) language structure.

TEXTS AND BASIC UNITS

A basic or crucial problem in analysing inscriptions is the segmentation of the text into contextually meaningful units in the context of communication. 3 There is consensus among scholars that discourse (oral or written) is composed of smaller segments (building blocks) in a coherent structure. Nevertheless, they differ in opinion about what these minimal segments are and how to identify them. In text and discourse-pragmatic analysis, notions such as 'Minimal Discourse Unit (MDU)' 'Basic Discourse Unit (BDU)' and 'Information Unit (IU)' are widely used. These terms, although they have some elements in common, show diverse views and are composed of multiple criteria, like illocutionary force, conceptual content, syntactic relations and prosody [START_REF] Degand | On identifying basic discourse units in speech: theoretical and empirical issues[END_REF]. The distinction between these different levels is neither clear-cut nor easy to establish. The unit of information is defined as information structure by Lambrecht who considers it an important factor in the structuring of sentences (Lambrecht 1994:3-6). 4Hence, in the case of Tamil epigraphic texts, reflecting the fact that information structure is context-dependent and marked linguistically in language-specific ways, we propose tentatively an extended notion viz. 'complete and contextually meaningful unit' (CMU) as the basis of our analysis, instead of segmenting the text into sentences and clauses. A complete and contextually meaningful unit is identified in aspects relevant to both structure (linguistic-syntactic clause) and text (contextualised information units). Each CMU may contain one or more smaller units, which may be called Information Units (IUs). The IU is used here as a component or part of CMU but does not imply any other pragmatic value such as representations of states of affairs are paired with lexicogrammatical structures in accordance with the mental states of interlocutors who use and interpret these structures as units of information in given discourse contexts" (Lambrecht 1994.3-6) . Van Valin also shares this view (Van Valin 1993).

'given', 'new', or 'information focus'. Each CMU or IU can be identified with a corresponding syntactical unit.

It is generally assumed that a syntactic clause and the discourse unit or IU are the same. 5 The clause is the minimal representation of the sentence, which is at a higher level. In other words, we can say that every sentence contains at least one clause. A sentence containing more than one clause is a complex sentence. A syntactic clause comprises a (core/nucleus) predicate, verbal and nonverbal. A verbal predicate may govern several core arguments (participants) encoded as subject and complements. 6The semantic and syntactic functions can be mapped variously, but with a transitive action predicate the agent/actor will always be selected as the subject and the object/undergoer as complement. A nonverbal clause is minimally made of two core constituents: the last one, in focal position, can be equated to the predicate. Several types of semantic relation may hold between the two core components (equative, possessive, attributive and so on) with various syntactic encodings. There may also be other temporal and locative adjuncts. For the sake of clarity, our analysis is based on a minimal syntactic unit (micro-syntax). This takes into account the core or nucleus and the arguments governed immediately by the nucleus. A minimal information unit is a subcomponent of a CMU.

The factors affecting the choice of constructions, as we will see, are importantly related to the information structure. In general, information structure includes concepts such as given and new information, topic, focus, theme, and rheme. However, we will rely for our description only on the saliency parameter (or newsworthiness concept (Mithun 1992). The most salient piece of information of these inscriptions is the identification of the person to whom the hero stone is dedicated. In the vast majority of the cases, it appears in the last word kal 'stone' of the inscription (or its operational part): "This is the hero-stone of ...". In some cases, the word kal is absent and we find in this focal end-position the word pa ā (die.past.3ms) which can be interpreted as "The one who is dead [and whose memorial stone it is] is...".

STRUCTURE OF AN INSCRIPTION

As mentioned above ( §1.1), an inscription generally contains the sequence of the three textual units: Preamble -Operational part -Conclusion. In our corpus, only the central unit, which contain the identification of the hero, is required. Each of the units is minimally equivalent to one CMU; the operational part, however, may contain more units.

1.

The Preamble, which conveys information related to the king and his regnal year, is regularly expressed through a dative attributive construction.

2.

The Operational Part, which obligatorily identifies the hero, is expressed through three basic structures: a proper name followed by kal 'This is the hero stone of X'; an identificational equative clause between the proper name (X) and the one who is dead pa ā (X') which can be expressed in one order X -X' or the other X' -X; and • a combination of both X -X' or X' -X followed by kal. The operational part may also contain additional information about the circumstances of the death of the hero. This information may be encoded in an adverbial clause forming an independent CMU or by sub-information units expressed by verbal nuclei dependent on X'.

3.

The last part, the Conclusion, giving details about person(s) who erected the memorial stone, is rare in our corpus, and is found only in one inscription (ex. 1).

The number of occurrences of these three structures is given in Table 1. To carry on the linguistic analysis of these inscriptions, we shall first present a complete inscription ( § 2). Then we analyze different components of the inscriptions: the Preamble, with its various forms and contextual meaning ( § 3) and the Operational part ( §4), divided in two sub-sections centred, respectively, on the grammar of the noun phrases ( §4.1) and the forms of the verbal nuclei ( §4.2). In section 5, we will discuss the main grammatical issues raised by the analysis of this corpus of inscriptions, before concluding ( §6).

Type

HERO STONE INSCRIPTION TEXT ANALYSIS

There are two preliminaries while reading a Tamil epigraphic text: (1) prior knowledge and (2) organizational structures of texts. By prior knowledge we mean the reader's shared knowledge (state of knowledge) of the world and society, in particular the world and society the inscription is talking about. This idea is related to the concept of "presupposition" as used in the theory of information structure and discourse analysis (Lambrecht, 1994:52, 213). For instance, while reading a 'Hero stone' inscription the reader is expected to possess or acquire a common idea that "hero stones are generally erected to commemorate the death of a warrior who died during a quarrel (skirmish)". In narrating this event, each sub event is marked in the text in an established order. The narrative order of events constitutes what we may call text structure, which conveys the information flow and coherence of the text. Therefore, the first rule in a grammar of epigraphic text is to identify the structure of the text. By identifying the organizational architecture of the text, one can observe how each constituent is subject to specific functional and structural constraints. The assumption here is that prior knowledge and the organizational structure of the text have a direct effect on its comprehension by the reader researcher.

To substantiate our analysis and arguments in the following chapters, we give in (A) below a sample analysis of a complete Hero stone inscription of the early period, with a translation. We have segmented the sample text in (A) into four CMUs (cf. examples 1-4). This hero stone inscription contains a canonical structure. 7By canonical structure we mean a text with a preamble (details about the king) and a notification (operational part). This is the case with most inscriptions. This sample text exceptionally includes a conclusion, the name of the founder(s) of the hero stone.

A. Chhs.1971-50. ( In what follows, we analyse the text and the four CMUs are repeated.

The preamble is an integral part of an epigraph but an exception to this general pattern is not rare. In our corpus, four inscriptions among 38, about 11%, are without the preamble.8 This part is very important as it conveys information about the king and his regnal year under whose reign the event happened. However, the preamble is not directly relevant to interpret the inscription and does not contribute to the propositional content of the operational part, because the king mentioned in the preamble is not a participant in the event described in the operational part of the inscription. Often this first unit functions as a conventional formula and conveys generic information. We call it generic, because other inscriptions may share the same information. This means that there may have taken place more than one skirmish in the same regnal year and during the reign of the same king. For instance, the events described in two different inscriptions, Chhs-1971.63 andChhs-1971.64, took place during the 33 rd regnal year of the king Vijayamahendravarman, thus both start with the same information, but with an orthographic variation in the name of the king.9

1. kōvicaiya maintira parumaṟku muppatteṭṭāvatu pn.dat 38.ord

In the 38th regnal year of the king Vijayamahendravarman

The preamble part is presented in (1) and constitutes a CMU. The nominal clause begins with the name of the king, the head noun, in dative case (-ku). The attributive expression, a numeral noun with the ordinal marker, is placed clause finally. This clause final numeral noun carries the salient (or news worthy) information. This structure resembles highly the dative inalienable possessive construction in modern Tamil, and is also known as attributive possessive predication. Nevertheless, in (1)

as there is no possessive relationship, this can be considered as an attributive clause (see § 3. for more discussion). The translation of the preamble is conventional and does not reflect its grammatical structure.

The operational part gives specific details about the event described in each inscription. This can be grouped under two major CMUs: (1) circumstantial and (2) the main event. These CMUs can be further divided into several information units: type of the dispute (the event), region where it took place (locative adjunct), name and identification of the deceased hero and other protagonists in the event (participants or arguments), manner or cause of the hero's death (adverbial participle), presentation of the memorial stone, and rarely, donors of the memorial stone. These suggest that the operational part, depending on the number of information units, may contain one or more main clauses.

The (2), a circumstantial clause, describes precisely the state of affairs of the main event, i.e. the death of the hero. The event (information) described in this unit, precedes the main event chronologically.

vāṇakō araicaru marumakkaḷ kantaviṇṇaṉār kūṭal toṟuk koṇṭa ñāṇṟu

pn kindred pn pln cattle-lift.rpp while While Kantaviṇṇanār (who is) the kindred of Vānakōaraisar cattle-lifted at Kūṭal, In (2), the clause starts with the cattle lifter's name (the subject of the event)

Kantaviṇṇaṉār. The proper noun is preceded by the noun phrase vāṇakō araicaru marumakkaḷ 'the kindred of Vāṇakōaraisar'. The function of this noun phrase is identificational, as this noun phrase helps to pin point the right person among others having the same name (for more discussion on proper noun phrases see § 4.1.1). The verb toṟu koḷa 'to cattle-lift', is composed of a noun toṟu 'cattle' and a verb koḷ 'to seize' and is considered here as a single unit. 10 This verb governs only one participant (the subject) who 'cattle-lifts' and a locative adjunct or complement, the village where the event took place. The place name kūṭal, where the dispute took place, is not case marked by a locative and immediately precedes the compound verb. The verb is in the past relative participle form because it is followed by the temporal noun ñāṉṟu 11 '(at) the time of'. The clause final temporal noun by its semantic and discursive role assures the flow of information and the textual coherence; the construction relative participle + ñāṉṟu will be regularly translated as 'while...'. The order of constituent is 'subject -event' ('SV').

In a traditional sense, (3) can be considered as a complex sentence combining three basic clauses or information units (IU). The adverbial participle clause (3.1) depends syntactically on the participial noun clause (3.2). Both verbs refer to the same human referent the proper noun and unique argument in these clauses. The two verb nuclei (adverbial participle and participial noun) have the same argument structure and govern the same argument as subject. The semantic relation (adverbial or causal) between these two clauses will be determined by many contextual factors. In (3.3), a nonverbal / genitive clause, the noun kal 'memorial stone' carries the salient information of not only the clause, but the whole text, and is placed clause final, in focus position. The proper noun Aṇṇāvaṉ precedes the memorial stone, the order possessor-possessee indicates the genitive relationship.

(kālam) time (vol.III.p.948). We will translate this term, throughout this paper as a conjunct "while". This translation seems to be more appropriate in the context of the text.

Each syntactic clause in (3) coincides with one minimal information unit. We can represent them as follows 1) 'Poṉṉarampaṉār (…) Aṇṇāvaṉ retrieved the (stolen) cattle', 2) 'Poṉṉarampaṉār (…) Aṇṇāvaṉ is dead (while retrieving the stolen cattle)' and 3) 'Here (this) is the memorial stone of Poṉṉarampaṉār (…) Aṇṇāvaṉ'.

In the sequence of adverbial participle and participial noun, we notice a causalresultative semantic nuance 'he is dead because / as he retrieved the (stolen) cattle' (for more details see § 4.2.2). This is a very rare inscription, which conveys information on the founder of the memorial stone. This last CMU is the equivalent of the Conclusion part in other types of inscriptions. 4. kūṭal iḷa-makkaḷ naṭuvitta kal.

Pln Young soldiers erect.rpp stone 'this memorial stone was erected by the young soldiers of (the village) Kūṭal'

The example (4) constitutes a CMU. The verb naṭuvi 'to erect' is a transitive/causative verb and governs two arguments. The subject of the action 'the soldiers of the village called Kūṭal', is in the initial position and the erected object 'memorial stone' is at the clause final position. In this occurrence, kal, 'memorial stone', the direct object complement, is relativized. The literal translation would be 'this is the memorial stone that the soldiers of Kūṭal (made) erected'. We can say else that the memorial stone is in focus position, like in (3). The relationship between focus and relative construction is not accidental (Paul Schachter 1973). The order of the constituent is subject-event-complement ('SVO').

Let us give a tentative summary of the structure of this sample inscription in (A). There are four CMUs, which are in turn divided into five minimum meaningful units. Each such meaningful unit coincides with a syntactic clause. A characteristic feature of Tamil epigraphic text is that a single nominal constituent can have more than one semantic role and serves as the pivot of the information as well as the grammatical structure. For instance, in (3), the human referent 'Poṉṉarampaṉār (…)

Aṇṇāvaṉ', has three different semantic roles. In the first case it is the subject (actor)

of the action toṟuiṭuvi 'to cattle-retrieve', in the second instance, it is the subject (undergoer) of paṭu 'to die', and in the third, it stands in a relation of attribution (possessor/benefactor) with kal 'the memorial stone', but the genitive relation is left unmarked. The salient (or news worthy) piece of information is placed in clause final focus position. For example, in (1) the numeral noun indicating the regnal year and in (3) and ( 4) the noun kal 'memorial stone' are placed clause finally. In what follows, we will analyse separately the preamble and the operational parts in order to picture some of the general features of hero stone inscriptions.

PREAMBLE

The preamble or the introductory section is an integral part of the inscriptional text. However, among 38 inscriptions of our corpus, four inscriptions do not contain the introductory part or the dynastic and chronological information. The remaining 34 give the name and the regnal year of the king under whose rule the dispute took place (see example (1)). Each preamble constitutes a CMU and represents syntactically a nonverbal attributive construction. The name of the king is in dative case and is placed clause initially. The numeral noun with the ordinal marker, the attributive expression, is placed clause finally. 12 All the 34 occurrences are schematically presented in (5).

king.DAT+ [year] +num.[ord.]

"n th regnal year to the king" (as for the king, it is his n th regnal year).

The elements placed in square brackets in (5) occur occasionally and so are not required to interpret the meaning of this CMU. Of these optional elements, one is a full lexical element yāṇṭu 'year' and the other is an ordinal morpheme. To put things in a different way, the dative marked king's name and the attributive expression numeral noun are the essential elements to make the predication semantically valid. Even in cases where the ordinal marker is absent, the intended meaning is understood contextually. The conventional translation of the Preamble is: 'In the [Number] th regnal year of the king [Proper Noun]...'

In the 34 CMUs containing information on the king and his regnal year, we have noticed three structures, as in ( In the third regnal year of the king Vijayavishnuvarman (as to the king Vijyavishnuvarman (it is his) 3 rd regnal year)

In ( 8) the lexical element corresponding to 'year' and the ordinal marker are missing. To a greater extent, based on the analogy of the dative inalienable possessive construction which is very common in (Modern) Tamil, one may understand (8) with an inalienable possessive interpretation, like: the king Vijayavishnuvarman has three sons / wives/ etc. In ( 7) and ( 8) the clauses remain ambiguous and this is mainly due to the absence of the lexical item corresponding to 'year', part of the predicate nucleus, on which depends completely the propositional content. These examples make obvious, as given in table 2, that one can interpret correctly only 9% of the occurrences and remaining 91% are difficult to understand correctly.

The question is how to account for the obvious difference between the formal structure of the sentence and its interpretation. The syntax involved is quite simple and any Tamil speaker, native or not, knows all the words. It is evident that this difficulty is not due to the degree of knowledge of the language. Instead, the difficulty is in correlating the knowledge that we possess about the relevant conceptual setting of the noun phrase and the shared knowledge. The truth is that we do not really understand what this noun phrase means until we know that this is a part of the preamble or the introductory part of a hero stone inscription. Further, we should also be aware that the information about the king and his regnal year are presented in the preamble of the inscription and all these are relevant to the textual structure of the inscription.

We will try to explain the difficulties in interpreting (6, 7 and 8) and in general the preamble part of hero stone inscriptions by using the concept of 'epigraphic formula' (formulaic expression), as is widely used in Latin and Greek inscriptions.

The concept of 'formula' is generally used in oral epics, and is defined, following Milman Parry, as "a group of words which is regularly employed under the same metrical conditions to express a given essential idea" (Adam Parry 1971). This concept also fits epigraphic techniques. In the case of Latin epigraphic texts, abbreviations and epigraphic formulae are an integral part of epigraphic techniques. However, in Tamil inscriptions, one can notice that abbreviations and formulae are repeated to express some readymade concepts. In the Tamil temple inscriptions, for instance, almost each text starts with the invocation formula (śvastī śṟī) 'let prosperity be', and the duration of the donation is indicated by another formula "candrādityavad" 'as long as the moon and sun exist'. At the end of the text, there are formulae of imprecation and benediction. All these and other readymade set of idiomatic expressions are repeated constantly at a specific section of the text and are part of the epigraphic style. The regular or conventionalised use of all these expressions forms a system of epigraphic techniques. Let us say, however, that the idea of a formula is conceptual and idiosyncratic and is beyond the realm of the linguistic framework. Scholars analysing Tamil classical poetics have made clear the function of formulaic expressions in Tamil (Kailasapathy 1962). 13 In the same manner, the formulaic nature of the introductory part of the hero stone inscriptions conveys a pre-established meaning. The very nature of repetition of a set of lexical elements, in particular at the beginning of the inscription, bears out its formulaic nature. 14 In the same vein, Richard Salomon recommends a comparative approach, in 'the interpretation of incomplete or otherwise problematic texts' and raises the notion formulaic nature of inscriptional texts. 15 It becomes evident from the examples (6, 7 and 8) that we have to distinguish carefully between two aspects: (1) the linguistic aspects of representing the formal 13 For instance, Kailasapathy mentions: "These instances clearly illustrate the point that such formulae are part of the stock-in-trade of the bards and are used when needed. " (1963.169). "Another type of formula that bears out its functional nature is to be found in specific places in a given poem, either at the beginning or at the end. ( …..) It has been pointed out that the bards have a way of beginning a conversation and ending it. The same observation could also be made of the Tamil songs (p.175).

14 "Repetition, for instance, is a striking feature of formulas which has figured in many of the definitions proposed" (Windelberg, Miller 1980:39). 15 "In addition to the requisite persistence and intuition, the interpretation of incomplete or otherwise problematic texts can be facilitated by a comparative approach. Because inscriptional texts tend, to a greater or lesser degree, to be formulaic and stereotyped, missing or uncertain sections of one inscription can often be clarified or reconstructed by comparison with related inscriptions of similar content" (Richard Salomon, 1998. 164-165).

meaning, and (2) the pragmatic aspects of interpretation among other things, the meaning intended by the speaker. 16 This corroborates our observation, made in the previous section, that the context is important, to a greater or lesser degree, to understand the conceptual or intended meaning of the text. Without the context, any utterance will fall in an inevitable lexical gap between the encoded and communicated meaning (Blunter 1999).

OPERATIONAL PART

The operational (or notification) part describes the central theme of the inscription.

We are concerned, in the present analysis, particularly about the event described in the inscription and the participants involved in that event and how they are represented in the text. Let us recall them briefly: for the events, the erection of hero stone, the death of the hero, the cause of the death, types of disputes or skirmishes (cattle-lifting, cattle-retrieval). The different participants evoked in hero stone inscriptions are the deceased hero, the participants in the skirmish and others mentioned as part of the text (scenario). Each proper noun phrase is attached to the nucleus verbal or nominal. Depending on the argument structure (type of event), the verb may govern one or two proper noun phrases having different functions like subject or complement.

The ways in which participants are identified, with proper names and complex determinative phrases, will be found in section 4.1.1, followed by the diversity of the relational marking of the complements of the verbs ( § 4.1.2). The types of verbal nuclei used to elaborate the operational part will be presented in section 4.2.

NOUN PHRASES 4.1.1. PROPER NOUN PHRASES: IDENTIFICATION OF THE HERO

The human participants are represented by a complex patronymic system composed of several noun phrases of professional titles and place names. They are formed by the simple juxtaposition of several nouns or noun phrases. In these sequences of noun phrases, the determinative always precedes the determinated, but the semantic relations may be of different types, mainly specificational or possessive (or more generally 'genitive').

In (9), the identification of the hero is composed of three nouns. ( ((((mī vēṇṇāṭṭu) karuṅkālipāṭi) āḷ) koṟṟavāciṟkarucāttaṉāru) makaṉ) kaṭṭaṅkaṇṇāru Kaṭṭaṅkaṇṇāru, (the son of (Koṟṟavāsir karusāttaṉār (the ruler/chief of (Karuṅkālipāṭi of (Mīveṇṇāṭu))))

These five dependent constituents provide two main Information Units:

Kaṭṭaṅkaṇṇāru is the son of Koṟṟavāsiṟkarucāttaṉ;

Koṟṟavāciṟkarucāttaṉ is the ruler of (the village) Karuṅkālpāṭi in mīvēṇṇāṭu

The second constituent (the village of) Karuṅkālipāṭi is determined as belonging to or part of (the district of) Mīveṇṇāṭu and the determinant is in oblique case. The relation between Koṟṟavāciṟkarucāttaṉ (the ruler), and mīvēṇṇāṭu karuṅkālippāṭi, (the ruled village) is expressed by the bare (lexical) stem āḷ 'to rule/the ruler'18 . The proper noun, Kaṭṭaṅkannāru, one of the participants, subject of the event is specified as the son of Koṟṟavācirkarucāttanāru. The order of constituents and their lexical meaning: proper name, place name or common relational lexeme (son of, ruler of) are the only hints to distinguish determinative appositional phrases from genitive relational phrases, except in the case of mīvēṇṇāṭṭu which is explicitly marked by an oblique case.

In some cases, a common noun is used to refer to the participant instead of a proper noun.

11 The examples 9-12 show the complexity of proper noun phrases. Each proper noun phrase is complex in the sense that it is constructed by a cluster of simplespecificational, genitive-phrases. In 9-12, the proper nouns are the subject of the event.

A good example of the elaborated identification of the hero of the memorial stone is found in a complete inscription, such as in ( 13).

( A non-human argument paṭai 'army' is marked in associative case -oṭu, indicating the object of the attack, while the place where the dispute had happened, semantically a locative adjunct, is marked with an oblique case -att depending on the verb20 . The construction of eṟi with two explicit complements is rare in our corpus. In this clause, the order of the complements and their marking seem to indicate that the grammatical hierarchy is C1 for the place name (closer to the verb and semantically less marked, oblique case) and C2 for 'army' (litt. 'fought with/against the army').

In ( 15), the two complement arguments are marked in locative and in associative cases respectively. ( 15) Dhar.1974-77.66 Vāṇakōmuttaraicar fought against his paternal uncle. All the three clauses have the same proper noun as subject. The first clause has a compound verb construction (nāṭu pā-C 0 V 'country-invade'). In the second clause, the complement argument, a place noun, is marked in locative case. The verb vara (literally means 'to come'), is used in this context with the meaning 'to attack'. The construction (with locative mēl) and the meaning are parallel to cel in the previous inscription. In the third clause, the verb eṟi, constructed with a human noun (kinship term) as complement ('direct object') marked in accusative case, gets the meaning of 'attack'. In our corpus, we have only two occurrences of accusative case and both are used with human nouns.

In the following clause, the complement argument occurs also without any case marker.

(17) Chhs.1971-33 (0595 CE.) kaṅkaraicaru makkaḷ poṉṉantiyāru perumukai eṟinta ñāṉṟu pn kindred pn pln fight.rpp conj while Po antiyāru, kindred of ka karaicaru attacked Perumukai 21 eṟi is a polysemous verb. For instance: (1) Tamil Lexicon: "to throw, cast; to hack, cut into pieces; to chop as mutton; to shiver into pieces; to destroy" etc. (2) The DEDR N° 859: "to throw, discharge, hack, chop, smash, destroy, beat, pounce, kick; throw, fling, kick; missiles; to strike, kick, butt, cut, cleave, pierce, kill; kicking, hitting, pushing, attacking; throw, beating (as of a drum), stroke (as of a sword), pouncing upon, destroying, scar". We use this term, according to the context, either with the meaning of "fight (against)' or "be wounded".

In ( 17), the complement of eṟi 'to fight, attack', perumukai a place name, is unmarked.

Contrary to nāṭu in ( 16) which is analysed as the C 0 of a compound verb due to its generic meaning 'to country-invade', the place name in (17) has to be treated as an independent complement (C1) due to its specific meaning.

In this section, we have examined the structure of noun phrases. The identity of the participant in the event is specified by the juxtaposition of different determinant constituents. In general, the complement (proper and place) nouns are inclined to be case marked.

TYPES OF VERB FORMS

In our corpus, we have 27 simple and compound verbs with 111 occurrences. The list of verbs and other relevant information are given in table 4. The verbs are arranged in the alphabetical order. Among the verbs in the first column, some are simple lexical units and some are compounds. Among the 27 verbs listed, paṭu 'to die' is used most frequently. Each derived or compound verb is listed under head lexical form. Most of these compound verbs are composed of two elements, a noun and verb. For example, see verbs 3, 7, 10, 13, 14, 15, 16, 18, 21, 24 and 26. There is only one occurrence of a compound verb composed of three elements (noun+verb+verb) (see verb 4). The formation of compound verb is rule governed and responds to all the morphological, syntactical and lexico-semantic properties of a simple verb. In some cases, there is a difference between the lexical and the contextual meaning (see for instance verbs 2 & 16). We have given both the lexical (usual) meaning (column 3) and the contextual meaning (column 4). All the information provided in this table is strictly contextual and is valid only for a specific type of texts, say Hero Stone inscriptions. All the meanings, in column 5, are inferred contextually. A background knowledge of the context is essential to calculate the meaning of these lexemes. Most of the interpretations given in Table 4 may not be available in a general Tamil language dictionary. The number of argument(s) presented in the 6 th column is strictly based on the clause structure of the inscriptions and this can not be generalised for the same verbs in other texts or contexts. For instance, the verbs 2 (cella 'to go') and 23 (vara 'to come'), which are usually one place (intransitive) verbs, can have contextually two participants in the argument structure, with significant difference in meaning.

The verbs, whatever their morphological form, are important for the lexical semantic aspects, as they allow us to form the argument structure of the clause. As we will see below, in many cases, the clause final position, the predicate position, is occupied by the focussed element or the salient piece of information. The next two sections will study the variation of the verb forms according to their function in the inscription.

In Tamil and in Dravidian, the verbal clauses are grouped into two broad categories: finite and non-finite. In Modern Tamil, for instance, it is fairly easy to identify a set of verb forms, conjugated in tense and person or with some modal value, which are exclusively used as the main predicate of a sentence. These forms are called finite. The term 'non-finite' covers two distinct set of forms. Roughly speaking, one can distinguish, on the one hand, the verbs forms which head a clause syntactically attached to another element, typically the 'participle' forms (adverbial, relative participles, etc.) and, on the other hand, the verb forms which are nominalised in one way or another and can be taken as the argument of a predicate.

In the corpus of inscriptions we studied, only a limited subset of these possible forms are attested: for instance, there are no modal forms, and some of the distinctions established above are problematic. A set of non-finite participle forms is clearly attested, and will be presented in section 4.2.2. What is more questionable is the existence of a set of distinctive finite personal forms. The difficulty which pertains to the textual type of the inscriptions and the formal ambiguity of the verb forms will be presented in the next section.

PERSONAL VERB FORMS

There are at least three reasons -formal, statistical and historical -in support of our line of questioning on the finite verb category. In modern Tamil, a distinctive feature of the finite verb forms in the Indicative mood is their variation in person, gender and number. The verb forms attested in the inscriptions are all in the 3 rd person and vary only formally in number: singular/plural. In modern Tamil, there are two types of forms based on the structure: verb stem+tense+person suffixes, the finite verb forms and the participial nouns. This last type is restricted to the 3 rd person and varies only in gender and number, with a set of person suffixes distinct from the ones used in the finite verb forms. In old Tamil, there is a subset of forms of the same structure (verb stem+tense+person suffixes), and these forms are identical whether they function as the main predicate of a sentence (finite verb) or as the argument of another verb (participial noun) (Rajam 1992:644-645). In the absence of any formal difference, the question is whether there are functional grounds to distinguish finite verb forms from participial nouns.

In general, the use of finite verbal forms in inscriptional Tamil is not very frequent. 22In our corpus, among 27 verbs, only one verb paṭu 'to die' occurs with person suffixes (3 rd masc. sg. or pl.). This verb occurs 34 times and is the most frequently used verb in our corpus. Among these occurrences, there are 29 personal forms of paṭu, but only five of them occur at the focal end-position where it clearly functions as the main predicate, in place of kal. The ratio of this use is very feeble, both compared to kal (13.88%) and compared to a total number of 111 verbal clauses (4.76%).

Another fact that supports our dilemma comes from the historical development of Tamil verbal morphology. Hero stone inscriptions, under analysis, reflect most likely a transitional period during which the diversification / specification of verbal morphology was gaining ground,23 but the morphological similarity between finite verbal and participial noun forms extend throughout classical and medieval Tamil, giving no cue in favour of one or the other interpretation. Finally, it is the textual type of the inscriptions which shed serious doubts on the necessity to interprete paṭṭāṉ/paṭṭāru as distinctive finite verb forms in this corpus.

In most of the cases, the verb paṭu 'to die', carrying a past tense morph and a third person marker (masculine singular or honorific plural), occurs in the last part of the core CMU ending in kal. As seen in Table 1, the personal verb form (X') is always in a relation of identification with a proper noun phrase (X). The two elements can appear in an alternative order preceding kal, 'the memorial stone' which they determine: X = X' kal (18) or X' = X kal (19). In both cases, the determiner of kal is a noun, proper noun or participial noun. Structurally, the reading of the text should be: "This is the memorial stone of (X') the one who is dead..., [who is] X..." in the first case and in reverse "This is the memorial stone of X..., the one who is dead (X')...". A fluid translation of the inscription does not always reflect these structural regularities.

In (18) the participial noun precedes the focused noun kal 'memorial stone'. In Hero stone inscriptions the most salient piece of information is found at the end of the core CMU of the operational part. Two lexical items occur in this position: the noun kal '(memorial) stone' and the verb paṭu 'to die'. The propositional referent of both these lexical items is the same human participant -the hero -who was dead, and in whose honour the memorial stone was established.

The noun kal 'memorial stone' occurs 30 times in our corpus. It is important to point out two features of this noun. First, the place of this noun kal never varies. It occurs always clause finally and thus falls in the focal position of the clause. Second, this noun is always determined by a preceding noun phrase, or by a relative participle or by a participial noun form of the verb paṭu 'to die'. From this fact we can deduce that the noun kal 'the memorial stone' stands high in the information saliency hierarchy as it is placed, without exception, in focal position.

The personal form of the verb paṭu appears clause finally in five instances. In all these five clauses, the noun kal does not occur at all. Syntactically, therefore, the personal form of the verb paṭu and the noun kal are in complementary distribution. Pragmatically, the personal form of the verb is placed in clause-final and focal position only if the noun 'memorial stone' does not occupy this position. In this position, compared to the preceding structures (X'-X/X-X' kal) where it functions as a determiner, it gains a privileged focal position and thus information saliency.

It is in this final, main predicate position that the personal forms of the verb are the most likely to be interpreted as finite verb forms. However, while the form of the verb is by itself ambiguous (participial noun/finite verb), the textual type of the inscription, which basically functions as an informative notice on the stone, as well the regular relation of identification with the proper name of the hero, favours, even in this case, the participial noun interpretation: "The one who is dead [and whose memorial stone it is] is X...".

In ( 20 The kindred of Kaṅkatiaraiyar of Aḷappai in Kōvvūru division is the one who died marching and fighting against Cinkaviṇṇaṉār.

The noun phrase 'the kindred of Ka katiaraiyar', is the subject argument of the three verbal nuclei (go, fight, die). The proper noun 'Ci kaviṇṇa ār', marked with the associative ōṭu 'against' is the complement argument of the adverbial participles of 'go' and 'fight'. In ( 20) and ( 21) the verb is placed clause finally, in predicate position.

NON-FINITE FORMS

Non-finite verbal forms are more frequent in inscriptional Tamil. They include the relative participle, the adverbial participle and the infinitive. Among 111 occurrences, 106 are non-finite (i.e. 95.49 %). Most of these non-finite forms function as determinants or qualifiers. We will discuss next all the different non-finite verbal forms.

RELATIVE PARTICIPLE

Both non-past and past relative participles are used in different types of constructions. There are 37 relative participle forms, of which 30 are past relative participle and seven are non-past relative participle. We will concentrate on the use of relative participles in two constructions: (1) proper noun phrases, and (2) temporal clauses with a temporal noun.

There are only seven non-past relative participles in our corpus. They are used in the proper noun phrases, as modifiers in specificational function.

(22) Dhar.1972-21.82 (0609 CE.) mīveṇṇāṭṭuk-kippaiūr āḷum vāṇikaru ….

pln.obl pln to rule.rp merchant..

'the merchant, the chief of Kippai ūr….

In ( 22), the head noun vaṇikaru 'merchant', is the subject argument of the event (country invading) described in the main clause. The modifying clause gives additional information about that merchant.

In ( 23), both non-past and past relative participles are used.

( The relative participle forms are used in two specific constructions. In one case, found in the proper noun phrase constructions, the relative clause, grammatically known as non-restrictive or explicative, functions like an appositional noun phrase which presents additional information to the referent of the head noun. The relative participle of āḷ 'to rule' (past āṇṭa in (12), non-past āl(l)um in 22-23), translated as 'the ruler of...' exemplify this use. In the second case, the relative clause, called restrictive, narrows the referent of the head noun to what is defined by the relative.

The past relative participles used with ñāṉṟu are used to depict various events linked to the death of the hero are restrictive. The relative participle is therefore a very flexible means to add complex information linked to the head noun it modifies.

We have seen in section 4.2.1, that the verb paṭu 'to die' plays an important role in the core information carried on the memorial stone. The past relative participle of this verb, paṭṭa, occurs in a few inscriptions, characteristically in a pre-final position as a modifier of kal. This construction appears as an alternative to the construction X -X' kal presented earlier ( §4.2.1). The syntactic link between the relative participle and its head-noun puts both paṭṭa (the idea of death) and kal (the memorial stone) in the most salient (final) position of the inscription.

ADVERBIAL PARTICIPLE

There are 30 occurrences of adverbial participle. They express simultaneous actions and other semantic relations with the main verb like cause, effect and manner.

Example ( 16) is repeated here as (27). In ( 27), a circumstantial clause, three verbal forms are used describing three events and they occur successively. Tēñaṇi Cāttaṇār was killed while (he) attacked Naripaḷḷi and quarrelled against Poṉmātaṉār, this is his memorial stone.

INFINITVE VERBAL FORM

The infinitives are not uncommon in inscriptions. The infinitival clause, like some adverbial participle clauses, expresses a cause-effect semantic relation with the main verb.

In ( 31) and ( 32) the infinitival clause describes the cause of the death of the hero.

There are two verbal clauses and the infinitival clause precedes the main verb. The events denote a cause-effect relation.

( The examples (31) and (32) represent an event consisting of two sub-events: a causing sub-event denoted by the infinitive verbal clause and another sub-event denoted by the main verb. The second main verbal clause can be construed as the result of the preceding event. This is also known as infinitive of cause, because the infinitive is used to express the cause of an action.

GRAMMATICAL ISSUES

The regularity -and relative simplicity -of the textual structure of the inscriptions found in our corpus contrasts with the variability -and relative ambiguity -of the grammatical means used in these inscriptions. Among the characteristic grammatical features worth being mentioned about these inscriptions is the use of the case markers. Absence of case markers is a well known feature of Old Tamil which can still be seen in our corpus of inscriptions. For instance, the adnominal relation is very rarely case-marked: the determinant of kal is never marked with a genitive "this is the memorial stone of…", the relation 'son/kindred/servant of …' are not marked (ex. 1, 9, 10, etc.); only the determinative relation for some place names (of/in…) is marked with an oblique (ṇāṭṭu in (10). Conversely, we also find the use of a great variety of markers with a given lexical verb (ex. eṟi + zero/obl/loc/assoc…case marker). In the Preamble, it is the lack of lexical and grammatical elements which makes its interpretation highly contextual.

A second point is the ambiguity with regard to the precise grammatical status of some elements. For instance, in construction (10), the bare stem āḷ is ambiguous. It can be interpreted as an appositive noun to Koṟṟavāciṟkarucāttaṉ, 'the ruler (of) Karuṅkālippāṭi..' , in a construction parallel to the one which occurs in the next noun phrase ...makaṉ, 'the son (of) Koṟṟavaāciṟ...' in apposition to Kaṭṭaṅkaṇṇāru) and in many other instances. The possibility of āḷ functioning as a noun is confirmed by the use of āḷ 'the chief' in (31), subject of toṟu[ko]ḷa 'cattle-lifting'. But, alternatively, āḷ in (10) can be interpreted as an uninflected verbal modifier 'ruling/who was ruling', functioning like a relative participle, as āṇṭa in (12) and āḷum in ( 22), a possibility also attested in later Tamil and other Dravidian languages. 24 The second case of ambiguity relates to the personal forms of the verb. In this corpus of inscriptions they occur only with the verb paṭu 'to die': paṭu + past tense + 3 rd pers masc. sg (paṭṭāṉ) or with a 3 rd pers. plural as a singular honorific (paṭṭāru). In most cases, they occur structurally in place of a noun : ... NP kal // .... paṭṭāṉ kal and are interpreted as participial nouns: '[This is] the memorial stone of NP.../ [This is] the memorial stone of the one who is dead...', usually as part of an identificational structure: <the one who is dead [is] NP > or in the reverse order < NP [is] the one who is dead> embedded under kal. In a few instances, these same forms paṭṭāṉ / paṭṭāru occur at the right end of the core CMU where it is likely to be interpreted as a finite verb predicate. In any other context, there would be no doubt about this interpretation, but in these memorial stone inscriptions, which are presentative rather than narrative and whose main function is to identify the hero of the memorial stone, the interpretation of these forms as participial nouns 'the one who is dead [is]...' seems to better fit the context.

CONCLUSION

How and / or what linguistic analysis would offer an understanding and interpretation of a variety of Tamil that is preserved only in writing? In this pilot study, we tried to show that a conceptual framework based on semantics and pragmatics would be more appropriate to delve into the meaning intended by the writer of the inscriptions. In this attempt, we have integrated the extra linguistic knowledge -both worldly contextual knowledge and knowledge of the structure of the text -as one of the conditions to interpret the meaning of discourse. The shared knowledge of the world and of society in particular is required for the interpretation of the core meaning of the text. A complete meaningful information unit (CMU) is taken as the basic unit of our analysis. Each CMU may be divided into subunits, the information unit. Each participant (noun or proper noun phrase) involved in an event establishes with the predicate a semantic role. These semantic roles, along with their respective predicates, are a means to understand the clause structure. The saliency of information plays a key role in determining the packaging of a sentence and hence the order of constituents. From this viewpoint the successful interpretation of information depends on the pragmatic information available to the Speaker and the Addressee. In this pilot study, we limited our analysis to the event, the participants in the event and their structural manifestation. There remain many other interesting and important issues to deal with.

Abbreviations: acc :accusative, adp :adverbial participle, ass :associative, dat :dative, hon: honorific, inf :infinitive, loc :locative, m : masculine, num: numeral noun, obl :oblique, ord: ordinal marker, pln :place noun, pn :proper noun, rp :non-past relative participle, rpp :past relative participle, s : singular, 3: third person,

Table 2 )

 2 :

	Type	Structure	Meaning	Total	Percentage
	1	king.DAT+year	to the king n th regnal	3	9%
		+num.ord.	year
	2	king.DAT+ num. ord	to the king n th	26	76%
	3	king.DAT+ num	to the king n	5	15%

TABLE 2

 2 ), the lexical element yāṇṭu 'year' is missing and may literally mean, "(as) to Somasikotiruman 21 st ". This lexical element is semantically necessary for the correct interpretation of the information. The clause in (7), without the context, may mean anything like '21 st victory/ child/ marriage to the king Somasikotiruman', but not 'in the 21 st regnal year of the king Somasikotiruman'.

	STRUCTURE OF ATTRIBUTIVE CONSTRUCTIONS
	They are illustrated respectively in (6), (7) and (8):
	(6) is the most explicit lexically and morphologically and there is correspondence
	between form and meaning.

  Akkantaikōṭaṉ, the servant of Poṉmōtaṉṉār ….. The last element, akkantaikoṭaṉ, is the name of the participant, subject of a complex verbal clause. The two preceding nominals poṉmōtaṉṉār and cēvakaṉ constitute a genitive phrase 'servant of Ponmotaṉṉar'. The genitive relation is indicated by the order of constituents, the possessor precedes the possessee. In (9) nothing is predicated about Akkantaikōṭaṉ, but the noun phrase poṉmōtaṉṉār cēvakaṉ specifies who he is. 17 Some proper noun phrases are composed of a series of dependant constituents. The element constituting the proper noun functions as head noun and the preceding elements function as modifiers.

	(9) Chhs.1971-88 (0612 CE.)
	…poṉmōtaṉṉār cēvakaṉ	akkantaikōṭaṉ ....
	pn	servant	pn
	….. (10) Chhs.1971-113 (0594 CE.)
	mī vēṇṇāṭṭu karuṅkālipāṭi āḷ	koṟṟavāciṟkarucāttaṉāru	makaṉ kaṭṭaṅkaṇṇāru
	pln.ob	pln	ruler	pn	son	pn

16 "The selection of what to inscribe and in what form to write it was never determined solely by what one wished to communicate or to record but by what was considered appropriate to communicate or to record in inscribed writing on a particular object in a particular place at a particular time"

(Bodel John, 2001. p.34)

.

Kaṭṭaṅkaṇṇāru, the son of Koṟṟavāsir karusāttaṉār the ruler/chief of Karuṅkālipāṭi in Mīveṇṇāṭu In (10), the proper name of the individual 'kaṭṭaṅkaṇṇāru' referred to in the text is the last constituent, whereas the preceding elements constitute a specificational noun phrase and are composed of different constituents with different relations among them. The proper noun phrase in 10 contains five dependant constituents, in which the preceding constituent specifies the following:

  Here, the information unit is the same as the one brought by āḷ in (10) above. The traditional translation of the sequence Place name-participle āṇṭa -Proper name as ' ProperN, the ruler of PlaceN...' emphasizes the functional equivalence of this verbal modifier ('ruling') with the appositional nouns (servant of.../ son of .../ruler of...) found in other sequences determinating the Proper Name.

	. Chhs.1971-77 (0598 CE.)
	mīvēṇṇāṭṭu āntai pāṭi īcai perumpāṇaraicaru marumakkaḷ poṟcēntiyāñ cēvakaru…
	pln.obl	pln	pn	kindred	pn	servant
	In some proper noun phrases, a relative participle form is used in the determinative
	slot instead of an appositional noun.
	12. Chhs.1971-33 (0595 CE.)
	… rārāṟṟū	āṇṭa	kuṉṟak kaṇṇiyār	kal
	... Pln	rule.rpp Pn	stone
	"This is the memorial stone of Kuṉṟakkaṇṇiyār ruling Rārāṟṟu …"

'The servant of Poṟcēntiyān and the kindred of Īcai Perumpāṇaraicaru of Āntaipāṭi in

Mīvaṇṇāṭu district…' In (11)

, the last constituent, 'servant' is the hero referred to in the text. The preceding constituents specify the noun 'servant': poṟcēntiyāṉ stands in a genitive relation to it, while the preceding string of nouns headed by marumakkaḷ constitutes an appositional phrase similar to the one headed by makaṉ in (10). The main IU of the whole noun phrase is that the hero, the servant of Poṟcēntiyān, is also the kindred of Īcai Perumpāṇaraicaru.

  post-positions) or in oblique case.19 A summary of the different morphemes and their function is given in table 3.

	N°	morpheme	case marker	function	frequency
	1	-tt	Oblique	C1	01
	2	-ai	Accusative	C1	02
	3	-mēl	Locative	C1	10
	4	-ōṭu	Associative	C1/C2	11
		TABLE 3: complement markers
	13) Damilica. 1970. p 93 (0550 CE.) vāṇavaruma araicaru cēvakaṉ uḻamaṇukaṉ makaṉ In (14), the clause contains two complements. pn king servant pn son (14) Chhs.1971-100 (0600CE.) koṅkaṇiaraicaru paṭai.oṭu ciri kaṅkaraicaru caṅkamaṅkalatt eṟinta vicayamaṅkalmāṇṭa pln.to rule.rpp ñāṉṟu viṇṇappērēnāti kal pn pn army.ass pn pln.obl attack.rpp while stone while kaṅkaraicaru attacked the army of ko kaṇiaraicaru at the village of 'This is the memorial stone of Viṇṇappērēnāti, the ruler of Vicayamaṅkalm, the son of Uḻamaṉukaṉ, a servant of the king Vāṇavarumaṉ. ca kama kalam….
					a single
	non-verbal clause is different from other examples (9-12) analysed in this section
	where the circumstances of the death of the hero are also detailed.
	4.1.2. COMPLEMENT NOUN PHRASES
	We will show, in the following section, the different morphological devices used to
	distinguish between subject and complement noun phrases. A complement
	argument occurs with two-place verbs. But, in our corpus all two-place verbs do not

(13) is a short inscription consisting of a single CMU. This CMU corresponds to a nonverbal clause with a nominal predicate kal 'memorial stone'. The memorial stone, which is the salient part of the information, occurs in the final -and focalposition of the clause. The nominal predicate (kal) is in genitive relation with the preceding -unmarked-proper noun Viṇṇappērēnāti. The name of the hero is specified by two appositional noun phrases, headed respectively by cēvakaṉ 'the servant of ...' and makaṉ 'the son of ...' and an adjectival phrase, headed by āṇṭa 'ruling' the relative participle of the verb āḷ. Here, as in (

12

), the information unit is the same as the one brought by āḷ in (10) above: ProperNoun ruling/the ruler of PlaceNoun. Within the nominal phrases, no genitive case marker specifies the possessive relation N of N (son/servant of N). This inscription made of explicitly govern a complement noun. The complement, both human and nonhuman nouns, is marked with (-ai) accusative, (-mēl) locative, or (-ōṭu) associative case markers (

  There are two verbal clauses. In the first instance, the non-human object, a place name is marked in locative case -mēl 'on' depending on the verb cel (which literally means 'to go'), used in this context with the meaning 'to attack' ('to go/march on'). In the second clause, with a different verb e i 'to fight', 21 a human complement (the adversary) is marked in associative case -oṭu 'with'.

	In (16), two complements are marked in locative and accusative morphemes
	respectively.
	(16) Chhs.1971-69 (0637 CE.)
	(...) vāṇakōmuttaraicaru	nāṭu pāviy	mēṟkōvalūr mēl	vantu
	(…) pn		country expand.adp	pln.loc	attack.adp
	tañ ciṟṟappaṭikaḷai	eṟinta	ñāṉṟu …
	his	paternal uncle.acc fight.rpp	while ….
	while Vāṇakōmuttaraicar expanded his territory attacked Mēṟkōvalūr and fought
	against his paternal uncle
	In (16) the adverbial CMU is composed of three clauses (IU): (1) Vāṇakōmuttaraicar
	country-invaded, (2) Vāṇakōmuttaraicar attacked the village of Mēṟkōvalūr and (3)
		(0605 CE.)
	poṟkōvaṇāru narippaḷḷi.mēṟ ceṉṟu	poṉmātaṉṉār.ōṭu erinta	ñāṉṟu ….
	Pn	pln.loc	to go.adp pn.ass	to fight.rpp while……
	…. while Poṟkōvaṉār attacked Naripaḷḷi and disputed with Poṉmātaṉṉār …..

TABLE 4 :

 4 LIST OF VERBS

  In (18) the participial noun paṭṭāṉ functions as the determiner of the memorial stone. It is preceded by an adverbial participle giving the circumstances of the death.

	In (19) the participial noun is placed clause initially.
	(19) Chhs.1971-68 (0637 CE.)
	….. paṭṭāṉ	kaṭuvantaiyār makaṉ viṟcitai	kal
	die.past.3ms	pn	son	pn	stone
	This is the memorial stone of Viṟcitai, the son of Kaṭuvantaiyār, (the one) who was
	dead...
	In (19) the proper name is determined by the two preceding constituents, … makaṉ
	and ... paṭṭāṉ, identifying the hero of the memorial stone.
	18) Dhar.1972-20-81 (0588 CE.)
	kāvativaṭukaṉ	toṟu-iṭuvittup		paṭṭāṉ	kal
	Pn	cattle-liberate.adp die. past.3ms	stone
	This is the memorial stone of kāvativaṭukaṉ, (the one) who was dead (while he)
	liberated cattle.

  ), the core CMU corresponds to an identificational clause with a personal verb form (participial noun) placed clause finally and interpreted as a nominal predicate (20)Chhs.1971-62 (0550 CE.)

	maṟu atiaraicaru cēvakaṉ	katavacātta paṭṭāṉ
	pn	servant	pn	die.past.3.ms
	Katavacātta, the servant of Maruatiaraicar is the one who is dead
	(21), contains two participants and a series of three verbal complex construction.
	(21) Dhar. 1974-164.52 (0577 CE.)
	kōvvūru nāṭṭu	aḷappai	kaṅkatiaraiyaru makkaḷ
	pln.obl	pln	pn	kindred
	ciṅkaviṇṇaṉārōṭu ceṉṟ.eṟintu.paṭṭāru
	pn.with	go.adp-fight.adp-die.past.3.hon

  23) Damilica 1970.p92 (0550 CE.)Dhar.1974.64. p. This proper noun is the subject argument of the verb āḷ 'to rule', and the complement of the verb 'come' indicating the target (-mēl 'on) of the attack (with an army that came against Gangaraisar). The first relative participle is a non-past form of the verb 'to rule', āllum, interpreted here as 'the ruler of'; it functions as specifier and presents additional information on the identity of the referent of the proper noun 'Kaṅkaraicar'. The next relative participle, vanta 'which came', is a past form, headed by the noun 'army' which is itself an argument of the past participle form of the verb eṟi 'to attack', eṟinta, headed by the temporal noun ñāṉṟu 'at the time when[someone] attacked'. The sequence ...eṟinta ñāṉṟu is regularly used to construct independent CMU, translated as 'while, during...', which details the circumstances of the death of the hero.As seen in the last two examples, any argument or indirect complement (a temporal adjunct in 23-24) of a clause can be taken to head a relative phrase.

	kuruvukaiyūr nāṭ.āllum	kaṅkaraisaru.mēl vanta	taṇṭatt.ōṭu
	pln.	to rule.rp		pn.on	come.rpp army.ass
	eṟinta	ñāṉṟu…
	attack.rpp	while
	…during an attack with an army that came against the Kaṅkaraicar ruler of
	Kuruvakaiyūr
	The first participant (kaṅkaraicar) bears two grammatical relations at the same time.
	In (24) the past relative participle of a different verb 'come' is used to specify ñāṉṟu
	in the construction of a temporal clause 'while...'.
	(24) Chhs.1971-96 (0591 CE.)
	kīḻvēṇāṭṭut	tuṭari mēl	vilakku miṟaiyār	vanta	ñāṉṟu
	pln.obl	pln	loc	pn	come.rpp while
	While Vilakkumiṟaiyār (attacked) went against Tuṭari of Kīḻvēṇāṭu

  Two events are represented by adverbial participles, one by a past relative participle and the final event by a participial noun. The adverbial participle vantu of the verb vara 'to come' is interpreted in this context as 'to wage war'. The first three events (to seizeattack-destroy) are successive and have the same argument as the subject (Vanakomuttaraisar). The adverbial participles are not directly related to the main verb but dependent on the temporal clause (eṟinta ñāṉṟu)… . The last event 'to die' Only few adverbial participle constructions denote successive actions. In the majority of the constructions the adverbial participial stands in a manner or causal relations with the event described by the verb paṭu 'to die'. , the main verb paṭu 'to die' is in participial noun form (see 4.2.1). In both clauses, the adverbial participle describes the manner or the cause of the death of the hero. The clause final nominal kal 'memorial stone' is in focal position and the preceding participial noun functions as a determinant of the hero stone.

	In (30), the adverbial participle indicates simultaneous or co-occurring action.
	(30) Dhar. 1974-77. 66 (0605 CE.)
	tēñaṇi-cāttaṉār (…) narippaḷḷi.mēṟ ceṉṟu	poṉmātaṉārōṭu eṟinta	ñāṉṟu
	pn			pln.loc	go.adp	pn.ass	fight.rpp conj
	represented by a participial noun form paṭṭāṉ constitutes a different clause and has a paṭṭār kal
	different subject. die.past.3.hon		stone
	(27) Chhs.1971-69 (0637 C.E.)
	vāṇakōmuttaraicaru nāṭu pāviy	mēṟkōvalūr.mēl	vantu
	pn			country.expand.adp pln.loc	(come) wage war.adp
	tañ ciṟṟappaṭikaḷai	eṟinta	ñāṉṟu paṭṭāṉ (…..)	māṟkaṭalaṉ
	his	paternal uncle.acc attack.rpp	while	die.past.3.m.s	pn
	'while Vāṇakōmuttataraicar seized, attacked Mēṟkōvalūr and attacked his paternal
	uncle, the one who died is Māṟkaṭalaṉ'
	In (28) the death of Eran can be interpreted as the result of his wounds, expressed
	by the adverbial participle form of eṟi 'be wounded'
	(28) Chhs.1971-96 (0591 CE.)
	….ēṟaṉ eṟintu	paṭṭāṉ
		pn cut.adp	die.past.3m.s
	Ēṟaṉ is the one who died being wounded….
	In (29) and (30)(29) Dhar.1972-20-81 (0500 CE.)
	kāvati vaṭukaṉ	toṟu iṭuvittup	paṭṭāṉ kal
	pn		cattle-liberate.adp	die.past.3ms stone
	this is the memorial stone of Kāvativaṭukaṉ who is dead liberating cattle

  31)Dhar.1973-3.84 (0575 CE.) This is the) memorial stone of Kumāracatiyar the warrior and the ruler of Kāppurai who is dead as (the) chief of Mokkaipāṭi in Puṟamalai lifted the cattle. memorial stone of Kiṇaṅkaṉ who was dead as the merchant invaded the village

	puṟamalaināṭṭu mokkappāṭi yāḷ	toṟu[ko]ḷa
	pln.obl	pl	chief cattle-lift.inf
	kāppuṟai	āḷum	maintaikaḷ kumārcatiyāru	paṭṭāru		kal.
	Pln	rule.rp	soldiers	pn	die.past. 3.hon	stone
	((32) Dhar.1972-21.82 (0609 CE.)
	…. vāṇikaru ūru	koḷa[ṭ]	paṭṭāru	kiṇaṅkaṉ	kal
	….. merchant	village	seize.inf	die.past.3.hon	pn	stone
	this is the

The list of abbreviations is given at the end of the text.

For more details on the grammatical evolution of Old Tamil, see Pilot-Raichoor in this volume.

The problem of segmentation is encountered not only in Tamil, but also in the study of all types of texts in ancient and in modern languages.

INFORMATION STRUCTURE: That component of sentence grammar in which propositions as conceptual

"The importance of clause structure in natural language is its universality: all languages have clauses, although there may be some difficulties in defining clause boundaries (…). The most plausible external explanation that comes immediately to mind is that the clause is the minimal complete information unit"(William Croft 1993: 33). Note also "let us assume that DS [discourse structure] is the organization of discourse units corresponding to clauses"(Komagata Nobo 2003:303).

Notions such as 'subject', 'object' are complex and their validity is not accepted equally. We use the term 'subject' in its traditional sense, as the first argument of the verb, instantiated as an independent nominative noun and/or in the person ending of the verb. Instead of 'object', we use the term 'complement', marked directly or indirectly, to designate the non-subject core arguments of an action verb.

Note that the hero stone inscriptions of later periods (roughly after

th century CE.) have a more elaborate structure and we see that the preamble (conventional part), for instance, contains two subparts, beginning with an invocation and followed by details of the ruling king.

The four inscriptions are: 1) āvaṇam-15.2 (0400 CE.), 2) āvaṇam-10.6. (0500 CE.), 3)Damulica-1970.92-93 (550 CE.) and 4)Chhs-1971.87 (0550 CE.).

The name of the king is written in two different ways: inChss.1971-63 "kōvicaiya macīntraparumaṟ" and in Chhs.1971-64 "kōviyaiya mayēntraparumaṟ".

It is`possible to consider the noun toṟu 'cattle' in toṟu koḷa 'to cattle raid' and in toṟu mīḷ 'to cattle retrieve' as the direct object of the verbs in each compound. However, due to their generic meaning, it seems better to treat them (and similar constructions found in our corpus) as compound verbs, forming a single verbal unit (C 0 -V), subject to lexical and morphosyntactic rules of word formation in Tamil. Note these two concepts are considered in ancient Tamil society as culturally accepted activities or events. This may be compared to the English verbs 'to baby-sit' or 'to window-shop', for example.

This word has several but related meanings, see for instance, DEDR 2920 Ta. ñāṉṛu, time, day, at the time of; Tamil Lexicon: 'time, day, at the time of'(p.1686) and Glossary of Historical Tamil Literature: (nāḷ) day,

This construction can be also analysed into topic-comment. The head noun in dative is the topic and the attribute, the numeral noun, is the comment, a nonverbal predicate.

The term specificational derives from the intuition that these clauses are used to specify who (or what) someone (or something) is, rather than to say anything about that person (or entity).(Mikkelson, forthcoming)

see below § 5 on the categorical ambiguity of this lexeme.

In our corpus the semantic role of arguments is not always morphologically marked. For instance, the genitive, locative, accusative are absent or replaced by the oblique form. But, -kku 'dative' in attributive head noun, and mēl, oṭu indicating the core complement argument(s), are marked almost regularly. Due to lack of space, we can not discuss this question in this paper.

In Modern Tamil, an oblique case can only stand in a noun-noun relation (of the genitive type) or before a postposition, but never in noun -verb relation.

I.[START_REF] Mahadevan | Early Tamil Epigraphy. From the Earliest Times to the Sixth Century A[END_REF], A. Murugaiyan 1999.

For more details, see Pilot-Raichoor in this volume

A function which is also well attested in other texts/languages, see[START_REF] Subrahmanyam | Verb bases as non-past adjectives in Old Tamil and Old Telugu[END_REF]


Florian Caillaud

Vincent Vidal

Florent Dupont

Guillaume Lavoué

Progressive compression of generic surface meshes

Keywords: Progressive compression, surface mesh, non-manifold, polygonal

à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

The amount of data describing 3D models does not stop increasing even though several applications (e.g. mobile device visualization, video games) are constrained by memory and/or processing speed. This situation may lead to communication or visualization latencies. The progressive compression of 3D models is a possible solution to this latency problem. The principle is to compress the 3D mesh while enabling its progressive decompression in the form of several Levels of Detail (LoD). In contrast of the so-called single-rate compression, progressive compression allows to quickly visualize a draft of the 3D model and then to rene it until the original mesh is retrieved. This oers more comfort to users and, sometimes, a quality control of the intermediate meshes.

Existing methods for progressive compression have mostly focused on 2-manifold and triangular meshes. Only few methods are able to progressively compress 1 Université de Lyon, CNRS 2 INSA-Lyon, LIRIS UMR 5205 3 Université Lyon 1 non-manifold surface meshes and none provide a generic compression of surface meshes, whatever their manifoldness or their faces degree. In this context, we present a lossless progressive compression method suited for non-manifold and/or polygonal meshes. Our approach is inspired by the seminal work from Popovi¢ and Hoppe [START_REF] Popovi¢ | Progressive simplicial complexes[END_REF] and introduce generic edge collapse and vertex split operators. The obvious additional cost of this genericity is balanced by an ecient local control of the distortion, which leads to excellent results at low and medium bitrates.

The rest of this paper is organized as follows : we introduce the previous work in Section 2. Then, our approach and its features are described in Section 3. Finally, Section 4 presents our results as well as comparison with the state of the art.

Progressive compression of 3D models has been introduced by Hoppe [START_REF] Hoppe | Progressive meshes[END_REF]. He proposed a simplication operator : the edge collapse. The main drawback of his method is its very ne granularity (dierence between two consecutive LoDs) which allows a strong control of the distortion but penalizes the compression rate. Moreover, like most of further progressive compression approaches [START_REF] Alliez | Progressive compression for lossless transmission of triangle meshes[END_REF][START_REF] Pajarola | Compressed progressive meshes[END_REF][START_REF] Karni | Ecient compression and rendering of multi-resolution meshes[END_REF][START_REF] Taubin | Progressive forest split compression[END_REF], it only deals with triangular manifold meshes.

Only few methods are able to compress polygonal manifold meshes. Maglo et al. [START_REF] Maglo | Progressive compression of manifold polygon meshes[END_REF] presents a generalization of the valence-based algorithm from Alliez and Desbrun [START_REF] Alliez | Progressive compression for lossless transmission of triangle meshes[END_REF] for this task.

Toward the progressive compression of non-manifold meshes, almost nothing exists in the literature. Popovi¢ and Hoppe [START_REF] Popovi¢ | Progressive simplicial complexes[END_REF] adapted [START_REF] Hoppe | Progressive meshes[END_REF] for this purpose. We particularly set apart tree-based methods from Gandoin and Devillers [START_REF] Gandoin | Progressive lossless compression of arbitrary simplicial complexes[END_REF] and Peng and Kuo [START_REF] Peng | Geometry-guided progressive lossless 3d mesh coding with octree (ot) decomposition[END_REF], which are very ecient at lossless rates but generate undesired quantization eects at low and medium bitrates. These techniques [START_REF] Gandoin | Progressive lossless compression of arbitrary simplicial complexes[END_REF][START_REF] Peng | Geometry-guided progressive lossless 3d mesh coding with octree (ot) decomposition[END_REF] handle non-manifold meshes but do not allow any local control of the decimation and thus of the distortion. Using a dierent bottom-up clustering strategy, Peng et al. [START_REF] Peng | Feature oriented progressive lossless mesh coding[END_REF] propose a progressive approach which provides nice low bitrate results however it does not guarantee to retrieve the lossless version. Furthermore, these techniques [START_REF] Popovi¢ | Progressive simplicial complexes[END_REF][START_REF] Gandoin | Progressive lossless compression of arbitrary simplicial complexes[END_REF][START_REF] Peng | Geometry-guided progressive lossless 3d mesh coding with octree (ot) decomposition[END_REF][START_REF] Peng | Feature oriented progressive lossless mesh coding[END_REF] are limited to triangular meshes.

In comparison, our method (1) handles both polygonal and non-manifold meshes, (2) allows a lossless retrieval of the mesh and (3) allows a precise local control of the decimation leading to excellent rate-distortion performance at low and medium bitrates.

3 Generic progressive compression

Compression pipeline

We describe, in this section, our progressive compression pipeline handling polygonal non-manifold meshes, i.e. every surface meshes.

We start by quantizing the mesh coordinates into Q bits. Then the mesh is simplied iteratively and the removed geometry and connectivity data are encoded into a compressed stream. This stream is structured so as to permit the progressive decompression and reconstruction of the original 3D model.

The simplication step is realized with a set of edge collapses (cf. Section 3.3.1) grouped in waves (cf. Section 3.3.2) similarly to [START_REF] Taubin | Progressive forest split compression[END_REF]. Each wave generates a LoD of the 3D model. The best set of edges to be removed at each iteration is selected using a metric (cf. Section 3.2) and its size (i.e. the number of edges to collapse) is automatically chosen. During this simplication, dierent types of data will be generated. Each type is encoded using a specic arithmetic coder.

Edge selection

As explained above, each simplication step decimates the mesh by a set of edge collapses. The edges to be collapsed are selected using a priority queue ordered by a weight w e associated to each edge e. The priority queue is updated after each collapse. Our idea here is to (1) select edge collapses that produce the less geometric error, (2) minimize the creation of dangling edges (i.e. edges without incident faces) because they cause losses of areas and (3) minimize the collapses of dangling edges because they may lead to a drastic reduction of the bounding box. For that purpose, if e is a dangling edge (case 3 above), w e = diag + length(e), if the collapse of e creates a dangling edge (case 2), w e = 2×diag+area(e), otherwise (case 1), w e = d H (e). diag is the bounding box diagonal length, area(e) is the area loss ratio caused by the hypothetical collapse of e and d H (e) is the symmetric Hausdor distance between the mesh before and after the hypothetical collapse. This way, we give priority to case 1, then 2, then 3.

The number of edges to be collapsed in each wave is critical. Indeed, if we select a very high number, then a large distortion could be introduced. To adapt this wave size, at the beginning of a wave we compute the weights of all edges. Then we determine a threshold as the average weight of these edges. Edges with weights superior than this threshold are not collapsed in this wave. This simple yet ecient rule provides excellent rate-distortion tradeos.

In order to avoid conict between two collapses during the same wave, edges included in the patch (set of incident faces) of an already selected edge, during the current wave, cannot be selected afterwards.

Progressive encoding

Generic Edge Collapse

The mesh simplication (resp. renement) is realized by our edge collapse (resp. vertex split) operator on each selected edge e. We introduce a generalisation of these operators to handle polygonal non-manifold local congurations. The edge collapse starts by removing the triangular incident faces of e (Figure 2-a). It removes e (Figure 2-b), which reduces the degree of polygonal incident faces of e. The operator then merges v and v (incident vertices of the removed edge e) in v without forgetting to solve the now duplicated edges and faces around v (Figure 2-c). Finally, v is displaced to the middle of the removed edge e.This new position is chosen as we only need one displacement vector to deduct the previous position of v and v (Figure 2-c).

Walk on mesh

Each simplication wave is decomposed in two parts. Firstly, edges are collapsed, in the order of the priority queue, until the weight threshold is reached. After each collapse, the priority queue is updated. Secondly, after having collapsed all the edges of the current wave, a spanning tree is build over each connected component of the mesh, using a lexicographic order. Each spanning tree starts on a xed vertex. This vertex is randomly chosen once on the original mesh since this choice does not aect the simplication. Each xed vertex stays during all the simplication and, therefore, cannot be removed (its incident edges can be collapsed anyway). This walk on the mesh provides an ordering of the edge collapses, thus an ordering of the vertex splits during renement, for each simplication wave.

This iteration is repeated until each connected component is compound by only one vertex. This vertex is the xed vertex of the corresponding connected component. This wave strategy avoid us to specify explicitly the edges to collapse (in contrast to [START_REF] Popovi¢ | Progressive simplicial complexes[END_REF]) , which drastically reduce the generated information.

Connectivity and geometry encoding

In order to provides the needed information for the mesh reconstruction, during each edge collapse, connectivity and geometry information will be generated.

Firstly, the connectivity around e (i.e. its adjacent faces and edges) is represented according to a general- ization of the connectivity cases from [START_REF] Popovi¢ | Progressive simplicial complexes[END_REF] (Figure 3). Actually, the dierent congurations are coded the same way (except for polygonal case 2.3) using the same topological constraints to reduce redundancy. Secondly, in order to preserve the face orientations at reconstruction, if they cannot be determined, we encode the orientation of the removed faces using one bit.

Thirdly, in order to eciently encode the displacement vector of v, we use its representation into a local Frenet frame. This representation is not especially optimal for local non-manifold congurations, but considering that most congurations are locally manifold, it still remains ecient.

Finally, during each simplication step, the spanning tree(s) allows to order this information so that the decompression has the corresponding data for each vertex to split. Obviously, we also need to specify which vertices will be split along the tree(s). For this purpose, during the construction, we encode a 1 if the visited vertex is resulting of an edge collapse, otherwise we encode a 0. As we forbid edge collapse conict, we do not encode a 0 if, at this state, we already encode a 1 for an adjacent vertex. [START_REF] Karni | Ecient compression and rendering of multi-resolution meshes[END_REF]

Results

We compare our generic progressive compression algorithm (GPC) with [START_REF] Peng | Geometry-guided progressive lossless 3d mesh coding with octree (ot) decomposition[END_REF] (PK05) and [START_REF] Peng | Feature oriented progressive lossless mesh coding[END_REF] (PHK10).

Table 1 shows the mean error given by METRO for dierent meshes of various complexity (both manifold and non-manifold). The data given by GPC are compared with the available data of PK05 and PHK10 (computed from the models provided by the authors). "N/A" values are due to early termination.

Figure 4 describes rate-distortion curves obtained with GPC, PK05 and PHK10 for the Horse and Rabbit models (triangular manifold) using MRMS metric. Despite a bit overhead due to the genericity of our method, Mesh(#v) Meth. the strong distortion control of GPC allows to obtain very competitive results at low and medium bitrates. We show, in Figure 1, dierent LoDs of the Tractor model to demonstrate the benet of our edge selection strategy. Furthermore, we visually compare three LoDs of the Skeleton model obtained with GPC, PK05 and PHK10 at the same bitrate (Figure 5).

Conclusion

We have proposed a generic method for the progressive compression of arbitrary surface meshes. This generic- ity involves an additional cost in the case of lossless compression. However, the strong distortion control allowed by our edge selection strategy makes our algorithm competitive at low and medium bitrates. As future works, we plan to investigate a more perceptual distortion control. We also plan to integrate progressive texture encoding in our pipeline.

Fig. 1

 1 Fig. 1 Progressive decompression of the Tractor model (polygonal non-manifold) at 3, 5, 10 bits per vertex and lossless.

Fig. 2

 2 Fig. 2 Dierent steps of the generic edge collapse of an edge e.

Fig. 3

 3 Fig. 3 Possible congurations around an edge e. (a) shows the generated codes, (b) edges congurations and (c) faces congurations.

Fig. 4

 4 Fig. 4 Rate-distortion curves of Horse and Rabbit measured with MRMS metric. The MRMS values are scaled by 10 4 .

Fig. 5

 5 Fig. 5 LoDs of the Skeleton model at 8 bpv using PK05, PHK10 and GPC compared to the original.

Table 1

 1

  Table of comparison between GPC, PK05 and PHK10 for dierent bitrates. The mean error values are scaled by 10 4 .

Previous work