Hesitant fuzzy parameterized hesitant fuzzy soft sets and their applications

The concept of the fuzzy set has an important role to model problems involving uncertainty. Since difficulties of the modelling of some problems are encountered in real life, some extensions of the fuzzy sets are needed. Recently, the concepts of hesitant fuzzy set and soft set which gain the attention of many researchers are some of them. In this thesis, the concept of hesitant fuzzy parameterized soft (HFPS) sets and set-theoretical operations of these sets are defined. Then, the notion of hesitant fuzzy parameterized hesitant fuzzy soft (HFPHFS) sets and their set-theoretical operations are introduced as a generalization of the HFPS sets. Fundamental definitions are supported with examples to make the concepts more understandable. Based on Hamming, Euclidean, and Hausdorff distances, some distance measure methods are introduced for HFPHFS sets. Then, two decision-making algorithms based on distance measure methods and aggregation operator are developed under the HFPHFS environment. Finally, some applications of the proposed methods in decision making are presented and compared to the existing methods.