A fuzzy set is a class of objects with a continuum of grades of membership. Such a set is characterized
by a membership (charac- teristic) function which assigns to each object a grade of member- ship ranging
between zero and one. The notions of inclusion, union, intersection, complement, relation, convexity, etc., are extended
to such sets, and various properties of these notions in the context of fuzzy sets are established. In particular,
a separation theorem for convex fuzzy sets is proved without requiring that the fuzzy sets be disjoint.