A series of score functions for hesitant fuzzy sets

This paper presents a series of score functions for hesitant fuzzy sets (HFSs) which provides us with a variety of new methods for ranking HFSs. The idea behind the methods is based on the score function for hesitant fuzzy elements (HFEs) that appears to be a subject worthy of further investigations in depth. The prominent characteristic of the HFS score-based method is that it can determine the priorities of the alternatives directly from the HFS score values. In a broad discussion, we describe a scheme for choosing an appropriate option from a set of HFS score-based methods according to what is expected from the score function and what is the nature of the values to be scored. Finally, the application of HFS ranking methods to multi-attribute decision making problems with hesitant fuzzy information is explained.