“…Among these extensions, type-2 fuzzy sets have been shown to hold a prominent position as they have been successfully applied in diverse fields [19,23]. The membership of an element x ∈ X to a type-2 fuzzy set A is given by a type one fuzzy set on the universe [0, 1], therefore a type-2 fuzzy set can be identified with an operator A : X → [0, 1] [0, 1] , where [0, 1] [0,1] is the set of functions whose domain and codomain is [0, 1].…”