Semantics for Constrained and Rational Default Logics
نویسنده
چکیده
The default nonmonotonic reasoning was formalised by a class of logical systems: default logics (classical, justified, constrained, rational), based on the same syntax which utilises nonmonotonic inference rules: defaults, but with different semantics for the defaults. In this paper we introduce a uniform semantic characterisation for the constrained and rational extensions of a default theory. This characterisation is an operational approach of the nonmonotonic reasoning that is viewed as a successive application of the applicable defaults. During the reasoning process can be observed the interaction between the defaults and the reasoning context. The graphical interpretation associated to the semantic characterisation of extensions illustrates the type of applicability: cautious (for constrained extensions) and hazardous (for rational extensions) of the defaults and some formal properties: semi-monotonicity, regularity, existence of extensions, commitment to assumptions of these variants of default logic.
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Constrained and Rational Default Logics
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