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<Paper uid="C00-2148">
  <Title>Integrating compositional semantics into a verb lexicon</Title>
  <Section position="2" start_page="0" end_page="0" type="intro">
    <SectionTitle>
1 Introduction
</SectionTitle>
    <Paragraph position="0"> The difficulty o1' achieving adequate hand-crafted semantic representations has limited the lield of natural language t)rocessing to applications that can be contained within well-deIined sub-domains.</Paragraph>
    <Paragraph position="1"> Despite many different lexicon development approaches (Mel'cuk, 1988; Copestakc and Sanfilippo, 1993; Lowe et al., 1997), the field has yet to develop a clear conseusus on guidelines for a colnputational lexicon. One of the most controversial areas in building such a lexicon is polyselny: how senses can be computationally distinguished and characterized. We address this problem hy employing compositional semantics and the adjunction of syntactic l)hrases to support regular verb sense extensions. This differs l'rom the Lexical Conceptual Structure (LCS) approach exemplified by Voss (1996), which requires a separate LCS representation for each possible sense extension. In this paper we describe the construction of VerbNet, a verb lexicon with explicitly stated syntactic and semantic information for individual lexical items, using Levin verb classes (Levin, 1993) to systematically construct lexical entries. We use Lexicalized Tree Adjoining Grammar (LTAG) (Joshi, 1987; Schabes, 1990) to capture the syntax for each verb class, and associate semantic predicates with each tree.</Paragraph>
    <Paragraph position="2"> Althougla similar ideas have been explored for w:rb sense extension (Pusteiovsky, 1995; Goldberg, 1995), our approach of applying LTAG to the problem of composing and extending verb senses is novel. LTAGs have an extended domain of locality that captures the arguments of a verb in a local manner. The association of semantic predicates to a tree yields a complete semantics for the verb. Moreovel, the operation of adjunction in LTAGs provides a mechanism for extending verb senses.</Paragraph>
  </Section>
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