A new evaluation method based on D-S generalized fuzzy soft sets and its application in medical diagnosis problem

Soft set theory, initiated by Molodtsov, is a general mathematical tool for dealing with uncertain problems. In this paper, we first point out that the similarity measure in a previous paper by Majumdar and Samanta [P. Majumdar, S.K. Samanta, Generalized fuzzy soft sets, Comput. Math. Appl. 59 (2010) 1425-1432] is limited by two counterexamples. To deal with the problems of subjective evaluation and uncertain knowledge, this paper proposes the concept of D-S generalized fuzzy soft sets by combining Dempster-Shafer theory of evidence and generalized fuzzy soft sets. We study some of its operations and basic properties, and the relationship between generalized fuzzy soft sets and D-S generalized fuzzy soft sets are introduced. Then we propose the concept of the similarity between two D-S generalized fuzzy soft sets. At last, we present a new method of evaluation based on D-S generalized fuzzy soft sets and apply it into a medical diagnosis problem.