Semistrictly preinvex fuzzy mappings

In this paper, we introduce the concepts of a strictly preinvex fuzzy mapping, a semistrictly preinvex fuzzy mapping, a strictly prequasi-invex fuzzy mapping and a semistrictly prequasi-invex fuzzy mapping. Some properties of these mappings and relations among them are studied. A few interesting theorems are proved, including that: (1) a strictly prequasi-invex fuzzy mapping has at most one global minimum point; (2) the solution set is invex if the fuzzy mapping is prequasi-invex and (3) prequasi-invex fuzzy mappings satisfy most of the basic properties of the preinvex fuzzy mappings.