Cohomología respecto a una variedad de una categoría.
Combinatorics of the free Baxter algebra.
Commutative directoids with sectionally antitone bijections
We study commutative directoids with a greatest element, which can be equipped with antitone bijections in every principal filter. These can be axiomatized as algebras with two binary operations satisfying four identities. A minimal subvariety of this variety is described.
Commutativity of Operators on the Lattice of Existence Varieties.
Commutator theory in strongly protomodular categories.
Compact elements in the lattice of varieties
We prove that the lattice of varieties contains almost no compact elements.
Compact universal relation in varieties with constants
Compatible Idempotent Terms in Universal Algebra
In universal algebra, we oftentimes encounter varieties that are not especially well-behaved from any point of view, but are such that all their members have a “well-behaved core”, i.e. subalgebras or quotients with satisfactory properties. Of special interest is the case in which this “core” is a retract determined by an idempotent endomorphism that is uniformly term definable (through a unary term ) in every member of the given variety. Here, we try to give a unified account of this phenomenon....
Complete generators and maximal completions of -algebras
Completely dissociative groupoids
In a groupoid, consider arbitrarily parenthesized expressions on the variables where each appears once and all variables appear in order of their indices. We call these expressions -ary formal products, and denote the set containing all of them by . If are distinct, the statement that and are equal for all values of is a generalized associative law. Among other results, we show that many small groupoids are completely dissociative, meaning that no generalized associative law holds...
Completeness theorem for the Evans logic of identities.
Completion varieties
Complexity of hypersubstitutions and lattices of varieties
Hypersubstitutions are mappings which map operation symbols to terms. The set of all hypersubstitutions of a given type forms a monoid with respect to the composition of operations. Together with a second binary operation, to be written as addition, the set of all hypersubstitutions of a given type forms a left-seminearring. Monoids and left-seminearrings of hypersubstitutions can be used to describe complete sublattices of the lattice of all varieties of algebras of a given type. The complexity...
Complexity of terms, composition, and hypersubstitution.
Concrete representation of some equivalence lattices
Conditions de Mal'cev et algèbres universelles uniformes
Conditions for factorable relations
Conditions for independence of varieties
Conditions for transitive principal tolerances
Congruence classes in regular varieties.