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<Paper uid="C02-1116">
  <Title>Linking syntactic and semantic arguments in a dependency-based formalism</Title>
  <Section position="7" start_page="4" end_page="4" type="concl">
    <SectionTitle>
6 Conclusion
</SectionTitle>
    <Paragraph position="0"> We proposed an architecture that abstractly captures reocurring patterns in the way in which different lexical items syntactically realize their semantic arguments. We focused on interchangeability between prepositional phrases and nominal phrases. We therefore defined a hierarchy of thematic roles, and a separate hierarchy of syntactic functions, clearly separating between syntax and semantics. null We enriched the framework of Topological Dependency Grammar (Duchier and Debusmann, 2001) (TDG) with a third level of representation, thematic structure, and defined well formedness conditions on the thematic structure and on the relation between thematic structure (TH) and syntactic dominance (ID) structure. This enabled us to present a formal definition of the concept of multi-level valency frames. We demonstrated how such valency frames can be assembled using the lexical inheritance model of TDG, in order to reduce lexical redundancy. We also proposed a treatment of auxiliary constructions using a notion of node collapsing. null We applied our formalism to English dative shift constructions, variation between NP and PP in German, optional complements, semantically empty elements, and thematic role alternations.</Paragraph>
    <Paragraph position="1"> Our approach makes weaker theoretical predictions about &amp;quot;alternations&amp;quot; as opposed to &amp;quot;alternative realizations&amp;quot; than the approach in (Davis, 1998), but is more powerful in the treatment of PPs. This is partly due to the choice of an underlying dependency formalism, because dependency structures lead to concise and semantically flat parse trees.</Paragraph>
    <Paragraph position="2"> Our approach is data-driven in the sense that a wider range of syntactic patterns can be mapped to semantic arguments. Thus, it lends itself easy to techniques of automatically acquiring lexica from syntactically and semantically annotated corpora, which start developing at present ((Baker et al., 1998), (Skut et al., 1998)).</Paragraph>
    <Paragraph position="3"> It is possible to include a mechanism that makes stronger predictions about alternations of the clear type, or about passivization. Another phenomenon we would like to tackle in this framework are raising and control constructions. We think we can use a concept similar to node collapsing for them.</Paragraph>
  </Section>
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