On fixed degree theorems for fuzzy mappings in Menger PM-spaces

In this paper, we establish a new common fixed degree theorem for a sequence of fuzzy mappings in Menger PM-spaces. As an immediate consequence of this theorem, we obtain an improvement of a corresponding result of Chang et al. (Fuzzy Sets and Systems 87 (1997) 325–334). In addition, we also obtain some fixed degree and fixed point theorems for fuzzy mappings in fuzzy metric spaces. Our results unify and generalize the results of Heilpern (J. Math. Anal. Appl. 83 (1981) 566–569), Butnariu (Fuzzy Sets and Systems 7 (1982) 191–207), Hadžíc (Fuzzy Sets and Systems 29 (1989) 115–125), Fang (Fuzzy Sets and Systems 48 (1992) 391–395), Lee et al. (Fuzzy Sets and Systems 61 (1994) 309–312; J. Fuzzy Math. 2 (1994) 859–870) and Chang et al. (Math. Japon. 40 (1994) 289–293; Fuzzy Sets and Systems 87 (1997) 325–334).