Divisible and exponent actions of semigroups.
Einige Bemerkungen zur Verzweigung des Punktes durch einen Komplex von Transformationen
Embedding in bisimple semigroups.
Embedding properties of endomorphism semigroups
Denote by PSelf Ω (resp., Self Ω) the partial (resp., full) transformation monoid over a set Ω, and by Sub V (resp., End V) the collection of all subspaces (resp., endomorphisms) of a vector space V. We prove various results that imply the following: (1) If card Ω ≥ 2, then Self Ω has a semigroup embedding into the dual of Self Γ iff . In particular, if Ω has at least two elements, then there exists no semigroup embedding from Self Ω into the dual of PSelf Ω. (2) If V is infinite-dimensional, then...
Embedding semigroups by translational hulls.
Embedding semigroups into semigroups with countability index two.
Embeddings in iteration groups and semigroups with nontrivial units.
Endomorphism monoids of bands.
Epimorphisms and dominions.
Epimorphisms of inverse semigroups of homeomorphisms between closed subsets.
Equivalences, a-semigroups and a-congruences.
Équivalences de Green dans les catégories bien filtrantes
Every group is a maximal subgroup of the semigroup of relations
Existence of joins and meets in the partially ordered family of CM-homomorphisms.
Extending partial isomorphisms and McAlister's covering theorem.
Factorizable as a finiteness condition.
Filtre sur un monoide fini.
Finite commutative monoids of open maps
Flatness and amalgamation in semigroups.
Four-part semigroups - semigroups of Boolean operations
Four-part semigroups form a new class of semigroups which became important when sets of Boolean operations which are closed under the binary superposition operation f + g := f(g,...,g), were studied. In this paper we describe the lattice of all subsemigroups of an arbitrary four-part semigroup, determine regular and idempotent elements, regular and idempotent subsemigroups, homomorphic images, Green's relations, and prove a representation theorem for four-part semigroups.