On Bimodal Nonmonotonic Logics and Their Unimodal and Nonmodal Equivalents
نویسنده
چکیده
We study a bimodal nonmonotonic logic MBNF suggested in [Lifschitz, 1994] as a generalization of a number of nonmonotonic formalisms We show first that it is equivalent to a certain nonmodal system involving rules of a special kind Next, it is shown that the latter admits a modal representation that uses only one modal opera tor the operator of belief Moreover, under this translation the models of MBNF correspond to ''expansions of the associated modal nonmonotonic logic Finally we show that, as far as such models are concerned, MBNF is redunhle to nonmodal default consequence relations from [Bochman, 1994] These results have general consequences concerning relationship between different formalizations of nonmonotonic reasoning
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