Topological semigroups of matrix units and countably compact Brandt $\lambda^0$-extensions of topological semigroups

Abstract

We show that a topological semigroup of finite partial bijections $\mathscr{I}_\lambda^n$ of an infinite set with a compact subsemigroup of idempotents is absolutely $H$-closed and any countably compact topological semigroup does not contain $\mathscr{I}_\lambda^n$ as a subsemigroup. We give sufficient conditions onto a topological semigroup $\mathscr{I}_\lambda^1$ to be non-$H$-closed. Also we describe the structure of countably compact Brandt $\lambda^0$-extensions of topological monoids and study the category of countably compact Brandt $\lambda^0$-extensions of topological monoids with zero.