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<Paper uid="C96-2144">
  <Title>A Constraint-based Case Frame Lexicon</Title>
  <Section position="2" start_page="0" end_page="0" type="intro">
    <SectionTitle>
1 Introduction
</SectionTitle>
    <Paragraph position="0"> -Recent adwmces in theoreticM and practical aspects of feature and constraint-based tbrmMisms for representing linguistic information have fostered research on the use of such formMisms in the design and implementation of computational lexicons (Briscoe el al., 1993). Case frame approach has been the representation of choice especially for languages with free constituent order, explicit case marking of noun phrases and embedded clauses filling nominal syntactic roles. The semantics of such syntactic role fillers are usually determined by their lexicM, semantic and morplmsyntactic properties, instead of position in the sentence. In this paper, we present an approach to building a constraint-based case Dame lexicon for use in natural language processing in Turkish.</Paragraph>
    <Paragraph position="1"> A number of observations tha.t we have made on Turkish tmve indicated that we have to go beyond the traditional transitive and intransitive distinction, and utilize a Damework where verb valence is considered as the obligatory co-existence of an arbitrary subset of possible arguments along with the obligatory exclusion of certain others, relative to a verb seuse. Additional morphosynt~ctic, lexical and semantic selectional constrMnts are utilized to map a given syntactic argument structure to a specific verb sense. In recent years, there have been several studies on constrmnt-based lexicons.</Paragraph>
    <Paragraph position="2"> iR,ussell el al. (1993) propose an approach to multiple default inheritance tbr unification-based lexicon. In another study by Lascarides et el. (1995), an ordered approach to default unification is suggested, de Paiva (1993) tbrmalizes the system of well-fornmd typed feature struetures. In this study, type hierarchies and relations are mathematically defined. They also formalize unification and generalization operators between tin(; featm:e structures, along with defining well-formedness notion that we use in our system.</Paragraph>
  </Section>
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