Negation in Disjunctive Logic Programs

Chiaki Sakama and Katsumi Inoue

Proceedings of the 10th International Conference on Logic Programming (ICLP'93), pp. 703-719, MIT Press, 1993.


In this paper, we study inferring negation from disjunctive logic programs. First, we consider extensions of the GCWA and the WGCWA for general disjunctive programs based upon the stable model semantics. We define new rules, the GCWA~ and the WGCWA~, which are natural extensions of the GCWA and the WGCWA. Second, we introduce a new semantics called the possible world semantics for general disjunctive programs, which was initially introduced in [Sakama 89] for positive disjunctive programs. The possible world assumption (PWA) infers negation under the possible world semantics, which lies between the GCWA and the WGCWA in positive disjunctive programs. The PWA is also extended to the PWA~ for general disjunctive programs. Then it is shown that the PWA~ provides a powerful and the most careful negative inference compared with the GCWA~ and the WGCWA~. We also present a bottom-up model generation proof procedure to compute each negation in general disjunctive programs.

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