Abstract

A logic program 1 is said to be equivalent to a logic program 2 in the sense of the answer set semantics if 1 and 2 have the same answer sets. We are interested in the following stronger condition: for every logic program , 1 [ has the same answer sets as 2 [ . The study of strong equivalence is important, because we learn from it how one can simplify a part of a logic program without looking at the rest of it. The main theorem shows that the verication of strong equivalence can be accomplished by checking the equivalence of formulas in a monotonic logic, called the logic of here-and-there, which is intermediate between classical logic and intuitionistic logic. 1 Introduction This paper is about logic programs with negation as failure under the answer set (\stable model") semantics [ Gelfond and Lifschitz, 1988 ] . A program 1 is said to be equivalent to a program 2 if 1 and 2 have the same answer sets. We are interested here in the following stronge...

Citations