Reflexive relations and Mal'tsev conditions for congruence lattice identities in modular varieties
Regularity in arithmetical varieties
Relative congruence distributivity within quasivarieties of nearly associative Φ-algebras
Relatively pseudocomplemented directoids
The concept of relative pseudocomplement is introduced in a commutative directoid. It is shown that the operation of relative pseudocomplementation can be characterized by identities and hence the class of these algebras forms a variety. This variety is congruence weakly regular and congruence distributive. A description of congruences via their kernels is presented and the kernels are characterized as the so-called -ideals.