Closedness properties of internal relations. IV: Expressing additivity of a category via subtractivity.
Coherence implies congruence-regularity (a local version)
Coherence in varieties of algebras
Commutator theory in strongly protomodular categories.
Compact universal relation in varieties with constants
Completeness theorem for the Evans logic of identities.
Conditions for factorable relations
Conditions for transitive principal tolerances
Congruence classes in regular varieties.
Congruence distributivity in varieties with constants
Congruence restrictions on axes
We give Mal’cev conditions for varieties 4V4 whose congruences on the product , are determined by their restrictions on the axes in .
Congruence submodularity
We present a countable infinite chain of conditions which are essentially weaker then congruence modularity (with exception of first two). For varieties of algebras, the third of these conditions, the so called 4-submodularity, is equivalent to congruence modularity. This is not true for single algebras in general. These conditions are characterized by Maltsev type conditions.
Congruences on products in varieties satisfying the CEP
Convex sets in algebras
Decidability of weak equational theories
Decomposability conditions for compatible relations
Decompositions of a -algebra.
Definability of principal congruences in equivalential algebras
Diassociativity is not finitely based relative to power associativity
We show that the variety of diassociative loops is not finitely based even relative to power associative loops with inverse property.
Direct decomposability of congruences in congruence-permutable varieties