Merging Logic Programs under Answer Set Semantics

This paper considers a semantic approach for merging logic programs under answer set semantics. Given logic programs P-1,...,P-n, the goal is to provide characterisations of the merging of these programs. Our formal techniques are based on notions of relative distance between the underlying SE models of the logic programs. Two approaches are examined. The first informally selects those models of the programs that vary the least from the models of the other programs. The second approach informally selects those models of a program P-0 that are closest to the models of programs P-1,...,P-n. P-0 can be thought of as analogous to a set of database integrity constraints. We examine formal properties of these operators and give encodings for computing the rnergings of a multiset of logic programs within the same logic programming framework. As a by-product, we provide a complexity analysis revealing that our operators do not increase the complexity of the base formalism.