Abstract

. Quite recently Brass/Dix have introduced the semantics D-WFS for general disjunctive logic programs. The interesting feature of this approach is that it is both semantically and proof-theoretically founded. Any program \Phi is associated a normalform res(\Phi), called the residual program. We show in this paper, that the original calculus, consisting of some simple transformations, has a very strong and appealing property: it is confluent . This means that all the transformations can be applied in any order: if we arrive at an irreducible program (no more transformation is applicable) then this is already the unique normalform. No proper subset of the calculus has this property. We also give an equivalent characterization of D-WFS in terms of iterated minimal model reasoning. This construction is a generalization of a description of the wellfounded semantics: we introduce a very simple and neat construction of a sequence D i that eventually stops and represents the set of derivable...

Citations