Some remarks concerning semi-T1/2 spaces

Abstract

In this paper we prove that each subspace of an Alexandroff T0-space is semi-T1/2. In particular, any subspace of the folder Xn, where n is a positive integer and X is either the Khalimsky line (Z, τK), the Marcus-Wyse plane (Z2, τMW) or any partially ordered set with the upper topology is semi-T1/2. Then we study the basic properties of spaces possessing the axiom semi-T1/2 such as finite productiveness and monotonicity.