Composing normal programs with function symbols

Abstract

Several expressive, decidable fragments of Answer Set Programming with function symbols have been identified over the past years. Undecidability results suggest that there are no maximal decidable program classes encompassing all these fragments; this raises a sort of interoperability question: Given two programs belonging to different fragments, does their union preserve the nice computational properties of each fragment? In this paper we give a positive answer to this question and outline two of its possible applications. First, membership to a "good" fragment can be checked once and independently for each program module; this allows modular answer set programming with function symbols. As a second application, we extend known decidability results, by showing how different forms of recursion can be simultaneously supported. © 2008 Springer Berlin Heidelberg.