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<Paper uid="W06-1522">
  <Title>Modeling and Analysis of Elliptic Coordination by Dynamic Exploitation of Derivation Forests in LTAG parsing</Title>
  <Section position="8" start_page="149" end_page="149" type="concl">
    <SectionTitle>
7 Conclusion
</SectionTitle>
    <Paragraph position="0"> We presented a general framework to model and to analyze elliptic constructions using simple mechanisms namely partial sharing and partial duplication through the use of a shared derivation forest in the LTAG framework. The main drawback of this approach is the use of tree schemata as part of parsing process because the anchoring process 10This mechanism without any restriction in the general case, can lead to a exponential complexity w.r.t to the length of the sentence.</Paragraph>
    <Paragraph position="1"> must have a extremely good precision choose algorithm when selecting the relevant trees. For the best of our knowledge it is one of the first time that merging tree schemata, shared forest walking and graph induction, i.e., working with three different levels of abstraction, is proposed. The mechanism we presented is powerful enough to model much more than the ellipsis of verbal heads and/or some of their arguments. To model elliptic coordinations for a given langage, the introduction of a specific saturation feature may be needed to prevent over-generation (as we presented in (Seddah and Sagot, 2006)). But the same mechanism can be used to go beyond standard elliptic coordinations. Indeed, the use of strongly structured anchors (e.g., with a distinction between the morphological lemma and the lexeme) could allow a fine-grained specification of partial value sharing phenomena (e.g. zeugmas).</Paragraph>
    <Paragraph position="2"> Apart from an actual large scale implementation of our approach (both in grammars and parsers), future work includes applying the technique described here to such more complex phenomena.</Paragraph>
  </Section>
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