Summary: Several properties of fuzzy semi-closure and fuzzy semi-interior of fuzzy sets, defined by A. M. Zahran
[Fuzzy Sets Syst. 116, No. 3, 353–359 (2000; Zbl 0995.54005
)], are established and supported by counterexamples. We also study characterizations and properties of fuzzy semi-open and fuzzy semi-closed sets. Moreover, we define fuzzy s-open and fuzzy s-closed mappings and give some interesting characterizations.