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<Paper uid="C92-1059">
  <Title>A TREATMENT OF NEGATIVE DESCRIPTIONS OF TYPED FEATURE STRUCTURES</Title>
  <Section position="6" start_page="0" end_page="0" type="concl">
    <SectionTitle>
,5 Conclusion
</SectionTitle>
    <Paragraph position="0"> \]'his paper has proposed an augmentatiotl of feature structures {FSs) which introduces negative information into FSs ill unification-based tbrmalisms.</Paragraph>
    <Paragraph position="1"> Unification-based linguistic formalisnm nse l&amp;quot;.qs to describe linguistic objects and phenotneua, l~ecanse linguistic information (:an |)e described compactly using disjunctive and uegatiw: descriptions, FSs and feao ture descriptions are required to treat such (lescriptrans, in this paper, FSs have been augnlent.ed, using a promising method of fornudizat.iou, Ait-l(aci's $~ type, to allow three kinds of negatiw~ descriptions of them to be treated.</Paragraph>
    <Paragraph position="2"> In a formalizalion of typed feature structures, negative descriptions can be decomposed rata three kinds of negations: negations of type sytnbols, negations of feature existences, aud llegations of feature-address value agreements. It. is shown thai the second and third kinds Call be treated by ailglncIItlllg tlrl'nl stlill% Lures to include structures representing such kinds of descriptions. Subsnmption relations on augmented terms are defined. It. is also shown that the first kind call be treated by exteuditlg type symbol lattices t() include complement type synd)ols.</Paragraph>
    <Paragraph position="3"> The proposed formalization cau provide efficient al-AcrEs DE COLING-92, NANTES, 23-28 AOl3&amp;quot;r 1992 3 8 $ PROC. OF COLING-92, Nhr, n'Es. AUG. 23-28. 1992 gorithms for generalization and unification operations as well as treat primitive negations. The formalization can be integrated with logic-based frameworks such as \[20\] which can treat wider ranges of descriptions but which do not have such efficient algorithms for these operations. Logic-based frameworks can be used to obtain the data structures for this paper's formalization.</Paragraph>
    <Paragraph position="4"> Unification algorithms for augmented terms or augmented TFSs have been developed using graph unification techniques. Unification programs based on these algorithms have been developed in Common Lisp.</Paragraph>
    <Paragraph position="5"> The augmentation of TFSs makes linguistic descriptions compact and easy to understand. In an HPSG-based grammar, for example, non-emptiness of a subcat or slash feature value can be easily described by nsing feature-address value disagreement.</Paragraph>
    <Paragraph position="6"> Moreover, negative descriptions make debugging proeessss of grammatical descriptions easier.</Paragraph>
  </Section>
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