A Framework for Nonmonotonic Reasoning with Rule Priorities
Masato Shibasaki and Katsumi Nitta
Department of Computational Intelligence and Systems Science, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226, Japan
In the 1990, a number of studies was made on nonmonotonic reasoning with rule priorities. Little is known, however, about relationships among these semantics because there is no framework in which these semantics can be compared. In this paper, we give the basis of this framework, which is a special form of Dung’s argumentation framework, although not covering all semantics of past studies in this category. To be concrete, we provide rule-based framework (RF) for extended logic programs (ELPs), clarify semantics of default rules and rule priorities, and extend it to RF for prioritized extended default logic programs (EDLPs). By means of RF for prioritized EDLPs, we reformulate several semantics of past studies , indicate their improvements, and give new prioritized EDLPs semantics.