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<Paper uid="P82-1016">
  <Title>An Improved Heuristic for Ellipsis Processing*</Title>
  <Section position="2" start_page="0" end_page="0" type="relat">
    <SectionTitle>
2. Related Work
</SectionTitle>
    <Paragraph position="0"> Several natural language systems (e.g., Bobrow et al., 1977; Hendrix et al., 1978; Kwasny and Sondheimer, 1979) include heuristics for replacement and repetition ellipsis, but not expansion ellipsis. One general strategy has been to substitute fragments into the analysis of the previous input, e.g., substituting parse trees of the elliptical input into the parse trees of the previous input in LIFER (Hendrix, et al., 1978). This only applies to inputs of the same type, e.g., repeated questions.</Paragraph>
    <Paragraph position="1"> Allen (1979) deals with some examples of expansion ellipsis, by fitting a parsed elliptical input into a model of the speaker's plan. This is similar to other methods that interpret fragments by placing them into prepared fields in frames or case slots (Schank et al., 1980; Hayes and Mouradian, 1980; Waltz, 1978). This approach seems most applicable to limited-domain systems.</Paragraph>
  </Section>
class="xml-element"></Paper>