On the number of closed subsets of linear functions in the 6-valued logic
On the one principal congruence identity
On the relation between heterogeneous uniform 2-algebraic closure operators and heterogeneous algebras.
On the representation of lattices by subsemigroup lattices of bands.
On the subsemilattices of first-order definable and openly first-order definable congruences of the congruence lattice of a universal algebra.
On tolerance relations
On t-semigroups.
On universal algebras having bases of different cardinalities
On varieties of regular -semigroups
On varieties of regular -semigroups, II
On weakly rigid monounary algebras
One simple result concerning imprimitivity relations of monoids of transformations and its applications.
One-element extensions in the variety generated by tournaments
We investigate congruences in one-element extensions of algebras in the variety generated by tournaments.
Operators and products in the lattice of existence varieties of regular semigroups.
Order affine completeness of lattices with Boolean congruence lattices
This paper grew out from attempts to determine which modular lattices of finite height are locally order affine complete. A surprising discovery was that one can go quite far without assuming the modularity itself. The only thing which matters is that the congruence lattice is finite Boolean. The local order affine completeness problem of such lattices easily reduces to the case when is a subdirect product of two simple lattices and . Our main result claims that such a lattice is locally...