Properties of 𝑆-closed spaces

It is shown that the S -closed spaces introduced by Travis Thompson using semiopen sets may be characterized as spaces where covers by regular closed sets have finite subcovers. S -closed is contagious and semiregular but is neither productive nor preserved by continuous surjections. Extremally disconnected QHC spaces are S -closed and maximal S -closed spaces are precisely the maximal QHC spaces which are extremally disconnected.