On the Existence of Answer Sets in Normal Extended Logic Programs

Martin Caminada and Chiaki Sakama

Proceedings of the 7th IJCAI International Workshop on Nonmontonic Reasoning, Action and Change, pages 25-32, January, 2007.


An often problematic feature in answer set programming is that a program does not always produce an answer set, even for programs which represent default information in a seemingly natural way. To cope with this problem, this paper introduces a class of normal extended logic programs which are extended logic programs, whose defeasible rules are comparable to normal defaults in default logic. Under suitable program transformations, we show that every normal extended logic program always yields at least one answer set.

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