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<Paper uid="J82-3002">
  <Title>An Efficient Easily Adaptable System for Interpreting Natural Language Queries 1</Title>
  <Section position="7" start_page="0" end_page="0" type="concl">
    <SectionTitle>
6. Conclusion
</SectionTitle>
    <Paragraph position="0"> We have shown how questions within a limited subset of English can be translated into a certain sub-set of logic which, when suitably transformed, is executable as efficient Prolog code. Although this mapping between English and logic may seem &amp;quot;obvious&amp;quot; (since logic is, after all, usually motivated in terms of its correspondence with natural language), it is surprising that a mapping like ours does not appear to have been implemented, or even precisely defined, before.</Paragraph>
    <Paragraph position="1"> Parts of the mapping overlap with Montague's 1974 formalisation of aspects of English, but many of the basics were not covered in his work (for instance, the treatment of questions, plurals, and determiner precedence), and of course he was not concerned to produce a practical implementation. Among practical implementations, the closest work is that of Woods 1977 and that of Colmerauer 1982 as implemented by Dahl 1981. Both these efforts are similar in that they map English into a nonstandard (and more elaborate) logic, where the quantifiers are more directly modelled on the determiners of natural language. These nonstandard quantifiers are called &amp;quot;FOR expressions&amp;quot; by Woods and &amp;quot;three-branched quantifiers&amp;quot; by Colmerauer. We have kept much closer to standard predicate logic, for the very down-to-earth reason that the traditional formalism seems to make &amp;quot;query optimisation&amp;quot; much easier (see the companion paper, Warren 1981).</Paragraph>
    <Paragraph position="2"> Our mapping from English to logic, as well as the processes of query planning and answering, have all been implemented entirely in Prolog. The result is a prototype natural language question answering system, Chat-80, which we think probably has the best combination of efficiency and portability of any comparable system at the present time, due principally to the use of Prolog as the implementation language.</Paragraph>
  </Section>
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