We call a restriction semigroup almost perfect if it is proper and the least congruence that
identifies all its projections is perfect. We show that any such semigroup is isomorphic to a …

This is the first of two articles studying the structure of left adequate and, more generally, of
left Ehresmann monoids. Motivated by a careful analysis of normal forms, we introduce here …

An appropriate generalization of the notion of permissible sets of inverse semigroups is
found within the class of weakly ample semigroups that allows us to introduce the notion of …

A left ample semigroup is a semigroup with a unary operation+ which has a (2, 1)-algebra
embedding into a symmetric inverse monoid I (X), the operation+ on I (X) being defined by …

We introduce an interesting class of left adequate monoids which we call pretzel monoids.
These, on the one hand, are monoids of birooted graphs with respect to a naturalglue-and …

The aim of this paper is to study a class of F-abundant semigroups, that is, u-IC quasi-
adequate semigroups. After giving some characterizations of u-IC quasiadequate …

In this paper, we investigate a class of factorisable IC quasi-adequate semigroups, so-
called, factorisable IC quasi-adequate semigroups of type-(H, I). Some characterizations of …

We introduce a notion of almost factorizability within the class of all locally inverse
semigroups by requiring a property of order ideals, and we prove that the almost factorizable …

In this paper, we investigate a class of factorisable IC quasi-adequate semigroups, so-
called, factorisable IC quasi-adequate semigroups of type-(H, I). Some characterizations of …

McAlister's P-theorem on E-unitary inverse semigroups and his theorem on E-unitary covers
are among the most beautiful results in semigroup theory. They have motivated research in …