On the characterization of a certain class of monounary algebras
On the characterization of Jonsson-Tarski and of subtractive varieties
On the characterization of primal partial algebras by strong regular hyperidentities.
On the Chinese remainder theorem of H. Draškovičová
On the congruence extension property.
On the congruence extension property for compact semigroups.
On the congruence lattice of stable algebras with definability of compact congruences
On the conversion of binary algebras into semi-primal algebras
On the degrees of permutability of subregular varieties
On the direct power of relational systems
On the dual space of an MS-algebra.
On the embedding of ...-algebras in groupoids.
On the existence of non-trivial tolerances in permutable algebras
On the failure of Birkhoff's theorem for locally small based equational categories of algebras
On the finite basis property for semigroup varieties.
On the greatest congruence relation contained in an equivalence relation and its applications to the algebraic theory of machines
On the homology theory of categories. I.
On the homology theory of categories. II.
On the join of equational classes of idempotent algebras and algebras with constants
On the lattice of completely regular monoid varieties.