Similarity measures of interval-valued fuzzysets

Abstract Interval-valued fuzzy set (briefly, IVFS) is a generalization of fuzzy set that may better model imperfect information. Similarity measure is a useful tool for determining the similarity degree between two fuzzy concepts. In this paper, the definition of similarity measure of IVFSs is presented. Three approaches to constructing similarity measures of IVFSs are proposed. Based on the approaches, three computation formulae for calculating the similarity degree between IVFSs are obtained. The properties of similarity measures of IVFSs are examined as a whole.