On formation of exception hierarchy

Abstract

In this paper, the rule specifying exceptions is discussed by using a representation original to the authors, the exc-representation, which can afford to express the hierarchy for exceptions. The hierarchy represents a kind of preference for incomplete knowledge in the inference. To form the rules, we focus on the contradiction derived by exceptions. Thus the rules to define the contradictions are of great importance in this paper. We devote the former half of this paper to discuss the definition of the exc-representation. We classify exceptions into the two types: the exceptions based on general-specific relation and the exceptions based on co-existence relation. For each type we define its representation. In the latter half, we propose a method to form the rules for each type. For the exceptions based on general-specific relation, our method is based on the inheritance rule on taxonomic hierarchy. For the co-existence relation, we produce the additional rules and predicates if necessary before forming the rules.

This work was partly supported by a Grant-in-Aid for the Ministry of Education of Japan

Research Fellow of the Japan Society for the Promotion of Science.