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<Paper uid="W91-0201">
  <Title>Knowledge represen tation and knowledge of words*</Title>
  <Section position="6" start_page="6" end_page="6" type="concl">
    <SectionTitle>
8. Conclusion
</SectionTitle>
    <Paragraph position="0"> Let's be clear about the problems.</Paragraph>
    <Paragraph position="1"> The field of knowledge representation began with a strong emphasis on applications in natural language understanding, but shifted its emphasis as it developed. This happened in part because the opportunities for productive research in the area are concentrated in relatively small scale, domain specific systems. It is hard to see how to build larger systems without sacrificing a clear understanding of what one is doing, and any hope of reliable performance. Thus, in returning to natural language understanding, we are straining the capabilities of what is known about representing knowledge. Since there is much interest in larger systems, and some hope of help from existing knowledge sources and from what linguists have learned about word meaning, lexieal semantics might be a promising area for research in scaling up knowledge representation. But we have to remember that we are trying to extend the field in ways that are pretty fundamental.</Paragraph>
    <Paragraph position="2"> Linguists have created a successful science by systematically ignoring cases where there are strong interactions between linguistic knowledge and broadly based world knowledge.</Paragraph>
    <Paragraph position="3"> They have developed a research methodology that works well for phonology, syntax, morphology, and some limited areas of semantics, but that breaks down in other areas of semantics and in pragmatics. They are comfortable with arguments that test representation systems for linguistic correctness, but not with ones that depend on engineering considerations like usability and transportability. Fairly radical departures from linguistic methodology are needed, I suspect, in establishing a unified theory of lexical semantics.</Paragraph>
    <Paragraph position="4"> To try to separate this project from tile task of building large scale knowledge bases is to settle for a partial solution, which may well turn out to be incompatible with systems providing the world knowledge that ultimately needs to be used in natural language processing applications.</Paragraph>
    <Paragraph position="5"> To integrate a computational semantics of words with knowledge representation tcchniques, we need to remember that representations can't be separated from reasoning. It is all too easy for any representation system to seem adequate until it is put to use in applications such as planning, that call for intensive reasoning. This requirement is probably going to be extremely difficult to observe in practice, but I think that we have to bear it in mind if we are going to have confidence in the representation systems that emerge from this work.</Paragraph>
  </Section>
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