F-γ-open sets and F-γ-continuity in fuzzy bitopological spaces

摘要

In this paper, we firstly introduce the concept of (δi,δj)-F-γ-open (resp., (δi,δj)-F-γ-closed) set which is weaker than each of the concepts of (δi,δj)-F-semiopen ((δi,δj)-F-semiclosed) set or (δi,δj)-F-preopen ((δi,δj)-F-preclosed) set. We study their properties and discuss the relationships between these concepts and relevant concepts in F-bitopological spaces. Using this new notion, we define the F-pγ-continuity as a generalization of F-pairwise semicontinuity [Fuzzy Sets Syst. 64 (1994) 421] and F-pairwise precontinuity [Fuzzy Sets Syst. 62 (1994) 231], and establish their various characteristic properties.