Fuzzy simple expansion

In this paper we generalize the concept of simple expansion due to Levine (1964) to the fuzzy setting. Also, we introduce new classes of fuzzy sets, namely fuzzy ηη-preopen sets, fuzzy weakly ηη-open sets and fuzzy weakly ηη-preopen sets. This families not only depend on the fuzzy topology ττ but also on it simple expansion and we study their fundamental properties.