Hesitant fuzzy ELECTRE II approach: A new way to handle multi-criteria decision making problems

Hesitant fuzzy set (HFS) permits the membership degrees of an element to a set represented by several possible values. Thus, it provides a suitable means to express uncertain information of different group members within the process of multi-criteria decision making (MCDM). In this paper, we suggest a new approach, named HF-ELECTRE II approach that combines the idea of HFSs with the ELECTRE II method, to efficiently handle different opinions of group members that are frequently encountered when handling the MCDM problems. We formulate the approach by defining the concepts of hesitant fuzzy concordance and discordance sets and by constructing the strong and weak outranking relations, which are employed to decide the ranking for a set of alternatives. Numerical examples are presented to exhibit the applications of the proposed method. Furthermore, a comparison of the alternatives’ rankings derived from the HF-ELECTRE II method with those derived from the aggregation operators and the fuzzy group ELECTRE approach is made. After that, a decision supporting system based on the HF-ELECTRE II method is constructed to aid decision making, and the prominent characteristics of the HF-ELECTRE II method and future research challenges are also discussed.