Talk by Massimo Poesio
Defeasible Reasoning with Underspecified Representations
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Many see underspecified representations as a tool that will allow us to
formalize sentence disambiguation as a defeasible reasoning process. Yet, the
existing theories of defeasible reasoning are built on the same assumptions
about inference that characterize more traditional forms of reasoning: we can
conclude that P is true if it can be derived from other wffs already known to
be true. But the only way proposed in the literature to make the initial,
underspecified interpretation of a sentence definitely true or false is to give
underspecified languages a `disjunctive' semantics which doesn't really capture
our intuitions about ambiguity. What we can do, however, is to `go meta', that
is, to model the disambiguation process as defeasible inference about what has
been uttered, rather than about the content of the utterance. The approach to
undespecification that results from this shift in perspective is also more
general than existing approaches, in that it can also be used to model
syntactic underspecification.
Paul Dekker, November 2, 1995