On group congruences on the semigroup $\boldsymbol{B}_ω^{\mathscr{F}}$ and its homomorphic retracts in the case when a family $\mathscr{F}$ consists of inductive non-empty subsets of $ω$

Abstract

We study group congruences on the semigroup $\boldsymbol{B}_ω^{\mathscr{F}}$ and its homomorphic retracts in the case when an $ω$-closed family $\mathscr{F}$ which consists of inductive non-empty subsets of $ω$. It is proven that a congruence $\mathfrak{C}$ on $\boldsymbol{B}_ω^{\mathscr{F}}$ is a group congruence if and only if its restriction on a subsemigroup of $\boldsymbol{B}_ω^{\mathscr{F}}$, which is isomorphic to the bicyclic semigroup, is not the identity relation. Also, all non-trivial homomorphic retracts and isomorphisms of the semigroup $\boldsymbol{B}_ω^{\mathscr{F}}$ are described.