Strongly equivalent logic programs
ACM Transactions on Computational Logic (TOCL) - Special issue devoted to Robert A. Kowalski
Nested expressions in logic programs
Annals of Mathematics and Artificial Intelligence
A New Logical Characterisation of Stable Models and Answer Sets
NMELP '96 Selected papers from the Non-Monotonic Extensions of Logic Programming
Meta Level Reasoning and Default Reasoning
JELIA '08 Proceedings of the 11th European conference on Logics in Artificial Intelligence
Rule Calculus: Semantics, Axioms and Applications
JELIA '08 Proceedings of the 11th European conference on Logics in Artificial Intelligence
Synonymous theories and knowledge representations in answer set programming
Journal of Computer and System Sciences
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Logic programs P and Q are strongly equivalent if, given any logic program R, programs P ∪ R and Q ∪ R are equivalent (that is, have the same answer sets). Strong equivalence is convenient for the study of equivalent transformations of logic programs: one can prove that a local change is correct without considering the whole program. Recently, Lifschitz, Pearce andV alverde showedt hat Heyting's logic of here-and-there can be used to characterize strong equivalence of logic programs. This paper offers a more direct characterization, and extends it to default logic. In their paper, Lifschitz, Pearce and Valverde study a very general form of logic programs, called"n ested" programs. For the study of strong equivalence of default theories, it is convenient to introduce a corresponding "nested" version of default logic, which generalizes Reiter's default logic.