“…The α-cuts or α-levels of a fuzzy set U , denoted by U α , are the intervals determined by the set of values verifying U (x) ≥ α, for α ∈ [0, 1]. Two of the most typical shapes of fuzzy sets considered in the literature are trapezoidal and triangular, where the last one is a special case of the first one (see, for instance, [8,12]). …”