A Practical Nonmonotonic Theory for Reasoning About Speech Acts
SRI INTERNATIONAL MENLO PARK CA ARTIFICIAL INTELLIGENCE CENTER
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A prerequisite to a theory of the way agents understand speech acts is a theory of how their beliefs and intentions are revised as a consequence of events. This process of attitude revision is an interesting domain for the application of non-monotonic reasoning because speech acts have a conventional aspect that is readily represented by defaults, but that interacts with an agents beliefs and intentions in many complex ways that may override the defaults. Perrault has developed a theory of speech acts, based on Rieters default logic, that captures the conventional aspect it does not, however, adequately account for certain easily observed facts about attitude revision resulting from speech acts. A natural theory of attitude revision seems to require a method of stating preferences among competing defaults. We present here a speech act theory, formalized in hierarchic autoepistemic logic a refinement of Moores autoepistemic logic, in which revision of both the speakers and hearers attitudes can be adequately described. As a collateral benefit, efficient automatic reasoning methods for the formalism exist The theory has been implemented and is now being employed by an utterance-planning system.