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Unfolding the well-founded semantics. (English) Zbl 1096.03504
Summary: We study the fixpoint completion for logic programs, proposed by P. M. Dung and K. Kanchanasut [(*) “A fixpoint approach to declarative semantics of logic programs”, in: Proceedings of the North American Conference on Logic Programming, MIT Press, 604–625 (1989)]. The fixpoint completion is a progam transformation – it performs a kind of unfolding of recursion through positive atoms in the clauses of a program – that was shown to preserve the semantics of a program in a certain sense. We generalize the results from (*) in some ways and show how the handling of negation is transformed by the fixpoint completion. We thereby obtain a more clarified view of both the fixpoint completion itself and the relatiotiship between well-founded and Fitting semantics for logic programs.

MSC:
03B70 Logic in computer science
68N17 Logic programming
68Q55 Semantics in the theory of computing
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