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<Paper uid="P89-1024">
  <Title>A HYBRID APPROACH TO REPRESENTATION IN THE JANUS NATURAL LANGUAGE PROCESSOR</Title>
  <Section position="9" start_page="199" end_page="200" type="concl">
    <SectionTitle>
7. Conclusions
</SectionTitle>
    <Paragraph position="0"> Our conclusions regarding the hybrid representation approach of intensional logic plus NIKL-based axioms to define constants are based on three kinds of efforts: * Bringing Janus up on two large expert system and data base applications within DARPA's Battle Management Programs. The combined lexicon in the effort is approximately 7,000 words (not counting morphological variations).</Paragraph>
    <Paragraph position="1"> * The efforts synopsized in Section 5 towards general purpose domain notions.</Paragraph>
    <Paragraph position="2"> * Experience in developing IRACQ and KNACQ, acquisition tools integrated with the domain model acquisition and maintenance facility KREME,  First, a taxonomic language with a formal semantics can supplement a higher order logic in support of efficient, limited inferences needed in a naturaJ language processor. Based on our experience and that of others, the axioms and limited inference algorithms can be used for classes of anaphora resolution, interpretation of have, with, and of, finding omitted relations in novel nominal compounds, applying selection restrictions, and mapping from the semantic representation of the input to code to carry out the user's request. null Second, an intensional logic can supplement a taxonomic language in trying to define word senses formally. Our effort with LDOCE definitions showed how little support is provided for defining word senses in a taxonomic language. A positive contribution of intensional logic is the ability to distinguish universal statements from generic ones from existential ones; definite sets from unspecified ones; and necessary and sufficient information from assertional information, allowing for a representation closer to the semantics of English.</Paragraph>
    <Paragraph position="3"> Third, the hybridization of axioms for taxonomic knowledge with an intensional logic does not allow us to represent all that we would like to, but does provide a very effective engineering approach. Out of 7,000 lexical entries (not counting morphological variations), only 0.1% represented concepts inappropriate for the formal semantics of NIKL.</Paragraph>
    <Paragraph position="4"> The ability to pre-compile pre-specified, inferential chains, to index them via concept name and role name, and to employ taxonomic inheritance for organizing knowledge were critical in selecting taxor~omic representation to supplement WML. These techniques of pre-compiling pre-specified inferential chains and of indexing them should also be applicable to other knowledge representations than taxonomies. At a later date, we hope to quantify the effectiveness of the semantic heuristics described in this paper.</Paragraph>
  </Section>
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