Über die Eindeutigkeit der Lösungen algebraischer Gleichungssysteme.
Über die Existenz von freien Algebren.
Über die Lösungsmengen von Gleichungssystemen über allgemeinen Algebren.
Über die Vollständigkeit der induktiven Gruppoide der partiellen Automorphismen von Algebren
Undecidable varieties with solvable word problems. III (a semigroup variety).
Unified polynomials for congruence principality
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.
Uniqueness of improper operations
Universal and internal properties of some extensions of partially orderd sets.
Unsolid and fluid strong varieties of partial algebras.
Upper semicomplements and a definable element in the lattice of groupoid varieties