Semigroups all but one of whose proper subsemigroups are groups.
Semigroups and lattices.
Semigroups and rings whose proper one-sided ideals are power joined
Semigroups and the structure of categories
Semigroups and their lattice of congruences.
Semigroups and their lattice of congruences II.
Semigroups and their natural order
Semigroups and their subsemigroup lattices.
Semigroups containing covered one-sided ideals
Semigroups containing covered two-sided ideals
Semigroups containing maximal ideals
Semigroups containing no maximal ideals.
Semigroups containing ubiquitous elements.
Semigroups defined by automaton extension mapping
We study semigroups generated by the restrictions of automaton extension (see, e.g., [3]) and give a characterization of automaton extensions that generate finite semigroups.
Semigroups for which all homomorphic images have complemented lattices of congruences.
Semigroups for which every S-system has the natural partial order.
Semigroups for which every totally irreducible -system is injective
Semigroups for which the continuum congruences form finite chains.
Semigroups in which a power of each element lies in a subgroup.
Semigroups in which ... and ... coincide for regular elements.