An interval approach to clustering

Generally, a linguistic expression attributed to a given situation is represented by a fuzzy set characterized by a membership function. The α level of this function is an interval. Therefore the notion of interval is implicit in the definition of a fuzzy set relative to the linguistic expression. Thus, the coding by interval is justified. However, the utilization of intervals is not restrained to the cases of linguistic expression coding. Indeed, the interval can facilitate the solution of several problems. We present a general form of fuzzy inclusion degree of two intervals, and some interesting applications