Some results on congruences on R-unipotent semigroups.
Some results on C-varieties
In an earlier paper, the second author generalized Eilenberg's variety theory by establishing a basic correspondence between certain classes of monoid morphisms and families of regular languages. We extend this theory in several directions. First, we prove a version of Reiterman's theorem concerning the definition of varieties by identities, and illustrate this result by describing the identities associated with languages of the form (a1a2...ak)+, where a1,...,ak are distinct letters. Next,...
Some results on finite maximal codes
Some results on generalized inverse semigroups.
Some results on ordered filters of implicative semigroups.
Some results on the dot-depth hierarchy.
Some results on -varieties
In an earlier paper, the second author generalized Eilenberg’s variety theory by establishing a basic correspondence between certain classes of monoid morphisms and families of regular languages. We extend this theory in several directions. First, we prove a version of Reiterman’s theorem concerning the definition of varieties by identities, and illustrate this result by describing the identities associated with languages of the form , where are distinct letters. Next, we generalize the notions...
Some structure theorems for inverse ω-semigroups
Some subdirectly irreducible idem-potent semigroups.
Sous-demi-groupes convexes des demi-groupes totalement ordonnés
Sous-monoïdes d’intersection complète de
Sous-monoïdes et automates
Sous-monoides et codes avec des mots infinis.
Spaces which admit negative powers and all roots (Preliminary communication)
Special congruence triples for a regular semigroup.
Spezielle Gleichungen in freien Halbgruppen und eine Anwendung auf Normalformen regulärer Ereignisse
Spirals of idemopotents from P-semigroups.
Splitting left distributive semigroups
S-sets and semigroups of quotients.
Stability and flatness in acts over monoids
Our aim in this paper is to study the concept of stability for acts over monoids and in the process develop connections with flatness properties of acts and with some of the current techniques and construction used in the homological classification of monoids. We also present new proofs of some results relating to torsion free acts over monoids and to the embeddability of semigroup amalgams.