Extensions of semigroups by symmetric inverse semigroups of a bounded finite rank

Abstract

We study the semigroup extension ${\mathcal{I}}_{\lambda }^n(S)$ of a semigroup $S$ by symmetric inverse semigroups of a bounded finite rank. We describe idempotents and regular elements of the semigroups ${\mathcal{I}}_{\lambda }^n(S)$ and $\overline{{\mathcal{I}}_{\lambda }^n}(S)$ show that the semigroup ${\mathcal{I}}_{\lambda }^n(S)$ ($\overline{{\mathcal{I}}_{\lambda }^n}(S)$) is regular, orthodox, inverse or stable if and only if so is $S$. Green's relations are described on the semigroup ${\mathcal{I}}_{\lambda }^n(S)$ for an arbitrary monoid $S$. We introduce the conception of a semigroup with strongly tight ideal series, and proved that for any infinite cardinal $\lambda$ and any positive integer $n$ the semigroup ${\mathcal{I}}_{\lambda }^n(S)$ has a strongly tight ideal series provides so has $S$. At the finish we show that for every compact Hausdorff semitopological monoid $(S,{\tau }_S)$ there exists a unique its compact topological extension $\left({\mathcal{I}}_{\lambda }^n(S),{\tau }_{\mathcal{I}}^{\mathbf{c}}\right)$ in the class of Haudorff semitopological semigroups.

24 pages