Similarity Criterion for Fuzzy Sets Defining in Fuzzy System

Fuzzy logic theory provides the most suitable tool for transforming verbal descriptions into mathematical models. Fuzzy modeling has great adaptability to the variations of system configuration and operation conditions. The fuzzy sets definition of a fuzzy system will influence the fuzzy inference performance, there is not a perfect criterion for fuzzy sets defining. A criterion via fuzzy similarity is prompted to evaluate the rationality of fuzzy sets which are defined in the universe of discourse. And an improved back-propagation algorithm is prompted based on the criterion.