Abstract: Unification-based grammar formalisms use feature structures to represent linguistic knowledge. The only operation defined on feature structures, unification, is information-combining and monotonic. Several authors have proposed nonmonotonic extensions of this formalism, as for a linguistically adequate description of certain natural language phenomena some kind of default reasoning seems essential. We argue that the effect of these proposals can be captured by means of one general, nonmonotonic, operation on feature structures, called default unification. We provide a formal semantics of the operation and demonstrate how some of the phenomena used to motivate nonmonotonic extensions of unification-based formalisms can be handled.
Publication Year: 1992
Publication Date: 1992-06-01
Language: en
Type: article
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Cited By Count: 43
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