Injectively and absolutely $T_{1}S$-closed semigroups

Abstract

A semigroup $X$ is $absolutely$ (resp. $injectively$) $T_{1}S$-$closed$ if for any (injective) homomorphism $h:X\to Y$ to a $T_1$ topological semigroup $Y\in \mathcal{C}$, the image $h[X]$ is closed in $Y$. We prove that a commutative semigroup $X$ is injectively $T_{1}S$-closed if and only if $X$ is bounded, nonsingular and Clifford-finite. Using this characterization, we prove that (1) every injectively $T_{1}S$-closed semigroup has injectively $T_{1}S$-closed center, and (2) every absolutely $T_{1}S$-closed semigroup has finite center.

18 pages. arXiv admin note: text overlap with arXiv:2207.12778