Polyboundedness of zero-closed semigroups

Taras Banakh, Andriy Rega

The polyboundedness number $\mathrm{cov}({\mathcal{A}}_X)$ of a semigroup $X$ is the smallest cardinality of a cover of $X$ by sets of the form $\{x\in X:a_{0}x{a}_1\cdots x{a}_n=b\}$ for s…