The successful Bellman-Zadeh concept of a symmetrical decision model in a fuzzy environment, with full symmetry between constraints and objective functions, has been an inspiration for researchers on the general field of fuzzy decision making. Since Zadeh introduced the notion of fuzzy set many other types and extensions of fuzzy sets have been proposed and applied to make decisions.

This Special Issue invites contributions addressing novel techniques and tools for decision making (e.g., group or multi-criteria decision making) with notions that overcome the problem of finding the membership degree of each element in Zadeh’s original model. We intend to garner articles in a variety of setups including fuzzy sets, fuzzy soft sets, type-2 fuzzy sets, interval-valued fuzzy sets, hesitant fuzzy set, fuzzy rough sets and rough fuzzy sets.