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<Paper uid="P01-1024">
  <Title>Topological Dependency Trees: A Constraint-Based Account of Linear Precedence</Title>
  <Section position="7" start_page="0" end_page="0" type="concl">
    <SectionTitle>
6 Conclusions
</SectionTitle>
    <Paragraph position="0"> In this article, we described a treatment of linear precedence that extends the constraint-based framework for dependency grammar proposed by Duchier (1999). We distinguished two orthogonal, yet mutually constraining tree structures: unordered, non-projective ID trees which capture purely syntactic dependencies, and ordered, projective LP trees which capture topological dependencies. Our theory is formulated in terms of (a) lexicalized constraints and (b) principles which govern 'climbing' conditions.</Paragraph>
    <Paragraph position="1"> We illustrated this theory with an application to the treatment of word order phenomena in the verbal complex of German verb final sentences, and demonstrated that these traditionally challenging phenomena emerge naturally from our simple and elegant account.</Paragraph>
    <Paragraph position="2"> Although we provided here an account specific to German, our framework intentionally permits the definition of arbitrary language-specific topologies. Whether this proves linguistically adequate in practice needs to be substantiated in future research.</Paragraph>
    <Paragraph position="3"> Characteristic of our approach is that the formal presentation defines valid analyses as the solutions of a constraint satisfaction problem which is amenable to efficient processing through constraint propagation. A prototype was implemented in Mozart/Oz and supports a parsing 4we also thank an anonymous reviewer for pointing out that our grammar fragment does not permit intraposition mode as well as a mode generating all licensed linearizations for a given input. It was used to prepare all examples in this article.</Paragraph>
    <Paragraph position="4"> While the preliminary results presented here are encouraging and demonstrate the potential of our approach to linear precedence, much work remains to be done to extend its coverage and to arrive at a cohesive and comprehensive grammar formalism.</Paragraph>
  </Section>
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