A Constructive Approach to Managing Fuzzy Subsets of Type 2 in Decision Making

The aim of this paper is to present a constructive methodology and algorithms for operations with fuzzy sets of type 2. The need to elaborate this methodology came from practical problems of Decision Making. To realize the methodology, some simplifications of the problem have been introduced. Particularly, only the trapezium form of membership functions was used. To highlight the difference between the proposed approach and the classical theory of fuzzy sets of type 2, the terms “hyperfuzzy set” and “hyperfuzzy function” have been introduced. Some base situations of hyperfuzzy functions with real arguments and real functions of hyperfuzzy arguments are performed.