A fuzzy reasoning method for handling fuzzy rules with different specificity levels

This paper discusses the fuzzy reasoning for fuzzy if-then rules with different specificity levels. The fuzzy rule-based system is a mixture of general and specific fuzzy if-then rules. A general fuzzy if-then rule, which has many "don't care" conditions in the antecedent part, covers a large region of a multi-dimensional input space. On the other hand, a specific fuzzy if-then rule with many linguistic conditions covers a small input region. The paper proposes a fuzzy reasoning method for realizing default hierarchies of fuzzy if-then rules where specific rules have priority over general rules in the fuzzy reasoning process. The proposed method is compared with a standard fuzzy reasoning method through computer simulations on an illustrative example.