Compositionality of normal open logic programs

Compositionality of programs is an important concern in knowledge represent ation and software development. In the context of Logic Programming, up til l now, the issue has mostly been studied for definite programs only. Here, we study compositionality in the context of normal open logic programming. This is a logic for knowledge representation in the context of uncertainty and incomplete knowledge an concepts and on problem domain, in which the co mpositionality issue turns up very naturally. The semantics of the logic is a generalisation (allowing non-Herbrand interpretations) of the well-found ed semantics. We provide a number of results which offer different sufficie nt conditions under which the models of the composition of two theories can be related to the intersection of the models of the composing theories. In particular, under these conditions, logical consequence will be preserved under composition. (C) 2000 Elsevier Science Inc. All rights reserved.