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Preferred subtheories: An extended logical framework for default reasoning. (English) Zbl 0713.68053
IJCAI 89, Proc. Int. Conf., Detroit, MI/USA 1989, 1043-1048 (1989).
[For the entire collection see Zbl 0707.68001.]
The standard approaches to formalize non-monotonic (and in particular, default) reasoning start from a consistent set of premises and extend the inference relation, e.g. by the addition of a second-order formula (J. McCarthy), or by the introduction of non-standard inference rules (R. Reiter) etc. The present paper considers an alternative view: that of seeing the default reasoning as a special case of inconsistency handling (an idea also proposed by Wolfgang Bibel), specifying strategies on the basis of the notion of preferred maximal consistent subsets of premises. Incorporating David Poole’s THEORIST approach to default reasoning, the author proposes two generalizations of Poole’s system: first, to consider several layers of possible hypotheses representing different degrees of reliability, and second distinguish between more or less reliable formulas based on establishing partial ordering between premises. In both approaches a formula is theoretically provable if it is possible to construct a consistent argument for it on the basis of the most reliable hypotheses.
Reviewer: N.Curteanu

68T15 Theorem proving (deduction, resolution, etc.) (MSC2010)