The archimedean graph of a positive function on a semigroup.
The center of translational hull and the hull of center of semigroup
The congruence class of an idempotent in a regular semigroup.
The congruences on S(X) which commute with V.
The homomorphic image of a T -semigroup.
The Hopf property and K-free products of semigroups.
The lattice of R-unipotent congruences on a regular semigroup.
The least inverse and orthodox congruences on a completely regular semigroup.
The least semilattice of groups congruence on a regular semigroup.
The least semilattice of groups congruence on an eventually regular semigroup.
The least separative congruence on a weakly commutative semigroup
The minimum reflexive subsemigroup generated generated by the sat of idempotents of a regular subsemigroup.
The monoid of strong endomorphisms of a graph.
The one-block property in varieties of semigroups.
The partially ordered family of C M-homomorphisms.
The semigroup generated by certain operators on the congruence lattice of a Clifford semigroup.
The structure of the automorphism group of a Croisot-Tessier semigroup.
The structure of the minimum group kernel of a regular semigroup
The structure of type A semigroups.
The tensor product of groupoids