A disjunctive semantics based on unfolding and bottom-up evaluation

We define a new semantics for disjunctive logic programs in an abstract way as the weakest semantics with certain properties, the most important being the unfolding-property (GPPE). Our semantics is similar to the strong well-founded semantics proposed by Ross, but seems to be more regularly behaved. It is an extension of both the well-founded semantics WFS and the generalized closed world semantics GCWA. We then present a bottom-up query-evaluation method for this semantics. An important feature of our approach is that we directly derive the algorithm from the given abstract properties of the logic programming semantics. The idea of the method is to compute derived rule instances with purely negative bodies (corresponding to Bry's conditional facts and Chen/Warren's residual program), and then to apply reduction steps in order to eliminate the conditions where possible. (orig.)Available from TIB Hannover: RO 6844(1994,16) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman