Relational classes and their characterizations
Relations, coverings, hypergraphs and matroids
Relations on the lattice of congruences of a regular semigroup.
Relative Complements in the Weak Congruence Lattice
Remark on partially ordered sets, universal algebras and semigroups
Remarks on tolerance algebras
Representation of undirected graphs by anticommutative conservative groupoids
The paper studies tolerances and congruences on anticommutative conservative groupoids. These groupoids can be assigned in a one-to-one way to undirected graphs.
Residual finiteness of a class of semigroups presented by a single relation.
Residually finite congruences and quasi-regular subsets in uniform algebras
Restricted congruence regularity of algebras.
Ring-like structures corresponding to generalized orthomodular lattices
Rough subalgebras of some binary algebras connected with logics.
Schreier-Zassenhaus theorem for algebras. I
Schreier-Zassenhaus theorem for algebras. II
Semigroups and their lattice of congruences II.
Semigroups and their subsemigroup lattices.
Semigroups for which the continuum congruences form finite chains.
Semigroups of transformations restricted by an equivalence
Suppose σ is an equivalence on a set X and let E(X, σ) denote the semigroup (under composition) of all α: X → X such that σ ⊆ α ∘ α −1. Here we characterise Green’s relations and ideals in E(X, σ). This is analogous to recent work by Sullivan on K(V, W), the semigroup (under composition) of all linear transformations β of a vector space V such that W ⊆ ker β, where W is a fixed subspace of V.
Semigroups with A-semidistributive subsemigroup lattices.
Semilattice decomposition of semigroups.