MATEMATIČKI VESNIK
МАТЕМАТИЧКИ ВЕСНИК



MATEMATIČKI VESNIK
On $s$-closedness and $\Cal S$-closedness in topological spaces
Zbigniew Duszyński

Abstract

Some properties of sets $s$-closed or $\Cal S$-closed relative to a space, and $s$-closed or $\Cal S$-closed subspaces, are obtained. Relationships between some of them are indicated. New characterizations of Hausdorff spaces in terms of $s$-closedness and $\alpha$-compactness relative to a space, are obtained.

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Keywords: $\alpha$-open; semi-open; preopen; semi-preopen; semi-regular sets; $s$-closed; $\Cal S$-closed.

MSC: 54G99

Pages:  199--214     

Volume  62 ,  Issue  3 ,  2010