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<Paper uid="C96-2204">
  <Title>Constructing Verb Semantic Classes for French: Methods and Evaluation</Title>
  <Section position="3" start_page="0" end_page="1127" type="intro">
    <SectionTitle>
2 The context system
</SectionTitle>
    <Paragraph position="0"/>
    <Section position="1" start_page="0" end_page="1127" type="sub_section">
      <SectionTitle>
2.1 General approach and motivations
</SectionTitle>
      <Paragraph position="0"> We. have refornmlated Beth Levin's notion of alternation into a more declarative one: the notion of context. A context is a Dame where the category and some additional syntactic is used to describe a precise form and position the argmneuts of a verb may have in a sentence. Verb classes are then formed from verbs having similar sets of contexts.</Paragraph>
      <Paragraph position="1"> Very briefly, compared to the alternation system, our approach avoids having to detlne a basic form from which alternations are produced and to have to explain what is the relation between a basic and an alternated form. Moreover, it avoids us to have to account for changes in meaning provoqued by alternations (e.g. by the adjunction of a preposition).</Paragraph>
      <Paragraph position="2"> l)etining contexts has led us to formulate a few principles: + contexts should be of general purpose, this means that: exceptional forms should be avoided, only non-mnbiguous and easy-to-use forms are acceptable, and theory-neutral descriptions should be used.</Paragraph>
      <Paragraph position="3"> - c.ontexts should minimally overlapp, * they must only describe lexical properties; the scope of a context is nsuMly a proposL tion * as less semantic data as possible should bc used, otherwise the classification will also be based on semantic criteria,  * the exact level of granularity of a context should be defined by feedback and retroevaluation on verbs, * consider generalizing two contexts into one, if their discriminatory power is low.</Paragraph>
      <Paragraph position="4"> These principles allow us to partly automate the determination those of contexts which can be associated with a given verb (for example by corpora inspection). However, there will always remain quite a lot of manual work to check and improve the results, in spite of some promising research in this direction (Dorr et al. 95a).</Paragraph>
      <Paragraph position="5"> As shall be seen below, the context system (which is not really a new concept) provides us with a very powerful tool for specifying and organizing the syntax and the semantics of verbs. Our contribution at this level is the way a context is defined, at what level of generality, with what formal means, and the way contexts are used to form verb classes.</Paragraph>
      <Paragraph position="6"> From a methodological point of view, contexts for French have been defined from a transposition of some English alternations (about 1/3 of our contexts), from French syntactic descriptions, among which (Gross 75), from corpora and from our own intuitions of language. Context coverage has then been validated on corpora to ensure that we cover most of the syntactic behaviors of arguments w.r.t, predicates.</Paragraph>
    </Section>
    <Section position="2" start_page="1127" end_page="1127" type="sub_section">
      <SectionTitle>
2.2 Description of contexts
</SectionTitle>
      <Paragraph position="0"> Contexts and the detailed criteria used to define them are presented in (Saint-Dizier 95). A context is a set of 'extended' distribution frames: l. a set: a cluster of syntactic forms which must all be valid for a given verb-sense. A verb accepts a certain context if it accepts all the distributions the context is composed of. A distribution is a list of syntactic constructions (NPs, PPs and sentences); this list is ordered and corresponds to the way these constructions are linearly realized in the surface form as arguments or modifiers.</Paragraph>
      <Paragraph position="1"> 2. 'extended': syntactic category distributions are expressed as a Type Feature Structure (written in Login (hit-Ka~i and Nasr 86)).</Paragraph>
      <Paragraph position="2"> We have identified several types of constraints: null * Local conslrainls on arguments or on ~he verb: thematic roles (including those defined in (Pngeault et al. 94), from (Dowty 89, 91)), the verb subcategorization frame, the arity of the verb, and a few commonly-admitted selectional restrictions.</Paragraph>
      <Paragraph position="3"> * Introduction of syntactic forms: coordination of arguments, introduction of reflexive pronouns and of a few modifiers.</Paragraph>
      <Paragraph position="4"> * Relations between arguments: thematic grids, modifier-modifiee relation between .arguments (e.g. noun complements), and expression of essential semantic relations: container-containee, and part-whole of various types.</Paragraph>
      <Paragraph position="5"> Our descriptions are more declarative than alternations, however, it is clear that this formalism allows us to introduce some forms of constraints between basis forms (via constraints on the verb) and the form being described. Similarly, the use of clusters of descriptions permits us to relate two forms.</Paragraph>
      <Paragraph position="6"> We have defined 70 contexts, including 'basic' contexts (corresponding to 'direct' realizations of argument structures) and non-basic ones. We have grouped the non-basic ones according to some similitudes into 17 subclasses. We have a total of 23 basic contexts (of general purpose) and 47 non-basic ones (there are 89 alternations in English). Non-basic contexts include the description of: middle reflexives, passives, inchoatives, place-subject inversion, introduction of the senti-auxiliary faire, support verbs with nominalization of the predicate (e.g. crier - pousser un cri), various forms of argument deletion, preposition change, reciproquals, body-part reformulations, means-instrument raising, reflexives, argument 'des-incorporation', perspective change, there insertion, etc.</Paragraph>
      <Paragraph position="7"> For example, we have the famous English spray/load alternation, which also exists m French, which is described as follows:</Paragraph>
      <Paragraph position="9"> ex( \[je, pulverise ,le ,mur ,de ,peinture\] ) )\] ) .</Paragraph>
      <Paragraph position="10"> 7, I spray the wall with paint (tg : general theme and loc : localization).</Paragraph>
    </Section>
  </Section>
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