Semi-preopen sets. (English) Zbl 0604.54002

In this paper each of semi-open sets, semi-closed sets, preopen sets, preclosed sets, \(\alpha\)-sets, and regular closed sets are further investigated and semi-preopen and semi-preclosed sets are introduced and investigated. Let (X,T) be a space and let A,B\(\subset X\). Then A is semi-preopen iff there exists a preopen set U such that \(U\subset A\subset \bar U\) and B is semi-preclosed iff X-B is semi-preopen. Also, the semi-closure, semi-interior, preclosure, and preinterior operators are further examined and the semi-preclosure and semi-preinterior operators are introduced and investigated.
Reviewer: Ch.Dorsett


54A05 Topological spaces and generalizations (closure spaces, etc.)