On equations of clones
On finite lattices which are embeddable in subsemigroup lattices.
On frame congruences generated by frame tolerances
Nuclei of frame congruences generated by frame tolerances and by lattice congruences are constructed.
On generalized conditionally commutative semigroups
On Grätzer's problem of binary 1-step congruence schemes
On ideals and congruences in BCC-algebras
We introduce a new concept of ideals in BCC-algebras and describe connections between such ideals and congruences.
On ideals in Hilbert algebras
On -ideals of semirings.
On k-radicals of Green's relations in semirings with a semilattice additive reduct
We introduce the k-radicals of Green's relations in semirings with a semilattice additive reduct, introduce the notion of left k-regular (right k-regular) semirings and characterize these semirings by k-radicals of Green's relations. We also characterize the semirings which are distributive lattices of left k-simple subsemirings by k-radicals of Green's relations.
On lattices embeddable into subsemigroup lattices. III: Nilpotent semigroups.
On left distributive left idempotent groupoids
We study the groupoids satisfying both the left distributivity and the left idempotency laws. We show that they possess a canonical congruence admitting an idempotent groupoid as factor. This congruence gives a construction of left idempotent left distributive groupoids from left distributive idempotent groupoids and right constant groupoids.
On medial local semigroups.
On modularity in lattices of congruences on ordered sets
On permutability in semigroup varieties
The paper contains characterizations of semigroup varieties whose semigroups with one generator (two generators) are permutable. Here all varieties of regular -semigroups are described in which each semigroup with two generators is permutable.
On pseudocomplemented semilattices with Stone congruence lattices
On quasivarieties of partial algebras, their generation and their subquasivarieties. I
On right congruences associated with the input semigroup S of automata.
On right congruences of semigroups.
On schemes for congruence distributivity
We present diagrammatic schemes characterizing congruence 3-permutable and distributive algebras. We show that a congruence 3-permutable algebra is congruence meetsemidistributive if and only if it is distributive. We characterize varieties of algebras satisfying the so-called triangular scheme by means of a Maltsev-type condition.
On semigroups with minimal or maximal condition on left congruences.