The well-founded semantics for general logic programs
Journal of the ACM (JACM)
Strongly equivalent logic programs
ACM Transactions on Computational Logic (TOCL) - Special issue devoted to Robert A. Kowalski
A New Logical Characterisation of Stable Models and Answer Sets
NMELP '96 Selected papers from the Non-Monotonic Extensions of Logic Programming
Minimum model semantics for logic programs with negation-as-failure
ACM Transactions on Computational Logic (TOCL)
A sufficient condition for strong equivalence under the well-founded semantics
ICLP'05 Proceedings of the 21st international conference on Logic Programming
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We consider the notion of strong equivalence [V. Lifschitz, D. Pearce, A. Valverde, Strongly equivalent logic programs, ACM Transactions on Computational Logic 2 (4) (2001) 526-541] of normal propositional logic programs under the infinite-valued semantics [P. Rondogiannis, W.W. Wadge, Minimum model semantics for logic programs with negation-as-failure, ACM Transactions on Computational Logic 6 (2) (2005) 441-467] (which is a purely model-theoretic semantics that is compatible with the well-founded one). We demonstrate that two such programs are strongly equivalent under the infinite-valued semantics if and only if they are logically equivalent in the corresponding infinite-valued logic. In particular, we show that strong equivalence of normal propositional logic programs is decidable, and more specifically coNP-complete. Our results have a direct implication for the well-founded semantics since, as we demonstrate, if two programs are strongly equivalent under the infinite-valued semantics, then they are also strongly equivalent under the well-founded semantics.