The Structure of Pseudo-Inverse Semigroups

A regular semigroup $S$ is called a pseudo-inverse semigroup if $eSe$ is an inverse semigroup for each $e = {e^2} \in S$. We show that every pseudo-inverse semigroup divides a semidirect product of a completely simple semigroup and a semilattice. We thereby give a structure theorem for pseudo-inverse semigroups in terms of groups, semilattices and morphisms. The structure theorem which is presented here generalizes several structure theorems which have been given for particular classes of pseudo-inverse semigroups by several authors, and thus contributes to a unification of the theory.