Tolerances on monounary algebras
Tolerances on poset algebras
To everz partiallz ordered set a certain groupoid is assigned. A tolerance on it is defined similarlz as a congruence, onlz the requirement of transitivitz is omitted. Some theorems concerning these tolerances are proved.
Tolerances on powers of a finite algebra
It is shown that any power , of a finite -element algebra , has factorable tolerances whenever the power has the same property.
Tolerances on -lattices
Tolerante Catalanzahlen
Total Algebras and Weak Independence. I.
Transferable principal congruences and regular algebras
Transformation semigroup diagram and the ...-relation.
Transitivity of principal tolerances is not a Mal'cev property
Two Congruence Lattices of Completely Simple Semigroups.
Two constructions of compatible relations
Über den Untergruppenverband der symmetrischen Gruppe, den Unterhalbgruppenver-band der symmetrischen Halbgruppe und den Unter-algebrenverband der Postchen Algebra.
Uniformity of congruences in coherent varieties
An algebra is uniform if for each , every two classes of have the same cardinality. It was shown by W. Taylor that coherent varieties need not be uniform (and vice versa). We show that every coherent variety having transferable congruences is uniform.
Varieties having directly decomposable congruence classes
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 tolerance and congruence extension property
Verbände von Kernen der Abbildungen, die orthogonaltreu sind
Weak coherence of congruences