We study the semigroup extension $\mathscr{ I}_\lambda^n(S)$ of a semigroup $S$ by symmetric inverse semigroups of a bounded finite rank. We describe idempotents and regular elements of the semigroups $\mathscr{ I}_\lambda^n(S)$ and $\overline{ \mathscr{ I}_\lambda^n}(S)$ show that the semigroup $\mathscr{ I}_\lambda^n(S)$ ($\overline{ \mathscr{ I}_\lambda^n}(S)$) is regular, orthodox, inverse or stable if and only if so is $S$. Green's relations are described on the semigroup $\mathscr{ I}_\lambda^n(S)$ 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 $\mathscr{ I}_\lambda^n(S)$ 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 $\left(\mathscr{ I}_\lambda^n(S),\tau_{ \mathscr{ I}}^\mathbf{ c}\right)$ in the class of Haudorff semitopological semigroups.
Categories: math.GR math.GN