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<Paper uid="P04-1004">
  <Title>Analysis of Mixed Natural and Symbolic Language Input in Mathematical Dialogs</Title>
  <Section position="3" start_page="0" end_page="0" type="intro">
    <SectionTitle>
2 Related work
</SectionTitle>
    <Paragraph position="0"> Language understanding in dialog systems, be it with text or speech interface, is commonly performed using shallow syntactic analysis combined with keyword spotting. Tutorial systems also successfully employ statistical methods which compare student responses to a model built from preconstructed gold-standard answers (Graesser et al., 2000). This is impossible for our dialogs, due to the presence of symbolic mathematical expressions.</Paragraph>
    <Paragraph position="1"> Moreover, the shallow techniques also remain oblivious of such aspects of discourse meaning as causal relations, modality, negation, or scope of quantifiers which are of crucial importance in our setting. When precise understanding is needed, tutorial systems either use menu- or template-based input, or use closed-questions to elicit short answers of little syntactic variation (Glass, 2001). However, this conflicts with the preference for flexible dialog in active learning (Moore, 1993).</Paragraph>
    <Paragraph position="2"> With regard to interpreting mathematical texts, (Zinn, 2003) and (Baur, 1999) present DRT analyses of course-book proofs. However, the language in our dialogs is more informal: natural language and symbolic mathematical expressions are mixed more freely, there is a higher degree and more variety of verbalization, and mathematical objects are not properly introduced. Moreover, both above approaches rely on typesetting and additional information that identifies mathematical symbols, formulae, and proof steps, whereas our input does not contain any such information. Forcing the user to delimit formulae would reduce the flexibility of the system, make the interface harder to use, and might not guarantee a clean separation of the natural language and the non-linguistic content anyway.</Paragraph>
  </Section>
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