Orthocompactness and semi-stratifiability in the density topology

Abstract

The density topology $\cal T$ is a topology on the real line, finer than the usual topology, having as its open sets the measurable subsets of ${\mathbb R}$, which are of density 1 at each of their points. The aim of this paper is to determine which subsets of the density topology are semi-stratifiable, orthocompact and weakly hereditarily pseudocompact.