<?xml version="1.0" standalone="yes"?>
<Paper uid="P98-1021">
  <Title>Spoken Dialogue Interpretation with the DOP Model</Title>
  <Section position="5" start_page="143" end_page="143" type="concl">
    <SectionTitle>
7. Conclusions
</SectionTitle>
    <Paragraph position="0"> We showed how the DOP model can be used for efficient and robust processing of spoken input in the OVIS spoken dialogue system. The system we described uses syntactically and semantically analyzed subtrees from the OVIS corpus to compute from an input word-graph the best utterance together with its meaning. We showed how dialogue context is integrated by dividing up the OVIS corpus into context-dependent subcorpora. Each system question triggers a subcorpus by which the user utterance is analyzed and interpreted.</Paragraph>
    <Paragraph position="1"> Efficiency was achieved by computing the most probable derivation rather than the most probable parse, and by restricting the depth and lexicalization of the OVIS subtrees. Robustness was achieved by the shallow syntactic/semantic annotations, including the use of the productive ERROR label for repairs and false starts. The experimental evaluation showed that DOP's blending of lexical relations with syntactic-semantic structure yields promising results. The experiments also indicated that elimination of subtrees diminishes the semantic accuracy, even when intuitively unimportant subtrees with only non-head words are discarded. Neglecting dialogue context also diminished the accuracy.</Paragraph>
    <Paragraph position="2"> As future research, we want to investigate further optimization techniques for DOP, including finite-state approximations. We want to enrich the OVIS utterances with discourse annotations, such as co-reference links, in order to cope with anaphora resolution. We will also extend the annotations with feature structures and/or functional structures associated with the surface structures so as to deal with more complex linguistic phenomena (see Bod &amp; Kaplan 1998).</Paragraph>
  </Section>
class="xml-element"></Paper>