Varieties of -groups are torsion classes
Varieties of operator semigroups representing partitions.
Varieties of partial algebras.
Varieties of subregular algebras are definable by a Mal'cev condition
Varieties satisfying ideal equalities
Varieties satisfying the triangular scheme need not be congruence distributive
A diagrammatic scheme characterizing congruence distributivity of congruence permutable algebras was introduced by the first author in 2001. It is known under the name Triangular Scheme. It is known that every congruence distributive algebra satisfies this scheme and an algebra satisfying the Triangular Scheme which is not congruence distributive was found by E. K. Horváth, G. Czédli and the autor in 2003. On the other hand, it was an open problem if a variety of algebras satisfying the Triangular...
Varieties which are locally regular and permutable at 0
Varieties with modular and distributive lattices of symmetric or reflexive relations
Varieties with tolerance and congruence extension property
Various remarks on quasi-universal model classes.
Verbände von Kernen der Abbildungen, die orthogonaltreu sind
Verbände von Kernen isotoner Abbildungen
V-кольца и их связь с группами автоморфизмов бинарных отношений
Weak automorphisms of 1-unary algebras
Weak automorphisms of integral domains
Weak automorphisms of linear spaces and of some other abstract algebras
Weak coherence of congruences
Weak congruence identities at 0.
Weak congruences of an algebra with the CEP and the WCIP
Here we consider the weak congruence lattice of an algebra with the congruence extension property (the CEP for short) and the weak congruence intersection property (briefly the WCIP). In the first section we give necessary and sufficient conditions for the semimodularity of that lattice. In the second part we characterize algebras whose weak congruences form complemented lattices.
Weak homomorphisms in implication algebra