Embeddings of Valued Groups.
Endomorphism semigroups of Brouwerian semilattices.
Engel BCI-algebras: an application of left and right commutators
We introduce Engel elements in a BCI-algebra by using left and right normed commutators, and some properties of these elements are studied. The notion of -Engel BCI-algebra as a natural generalization of commutative BCI-algebras is introduced, and we discuss Engel BCI-algebra, which is defined by left and right normed commutators. In particular, we prove that any nilpotent BCI-algebra of type is an Engel BCI-algebra, but solvable BCI-algebras are not Engel, generally. Also, it is proved that...
Epi-archimedean groups
Equational spectrum of Hilbert varieties
We prove that an equational class of Hilbert algebras cannot be defined by a single equation. In particular Hilbert algebras and implication algebras are not one-based. Also, we use a seminal theorem of Alfred Tarski in equational logic to characterize the set of cardinalities of all finite irredundant bases of the varieties of Hilbert algebras, implication algebras and commutative BCK algebras: all these varieties can be defined by independent bases of n elements, for each n > 1.
Equitable partitions of continuum
Erratum to “On homological classification of pomonoids by regular weak injectivity properties of S-posets”
The original version of the article was published in Central European Journal of Mathematics, 2007, 5(1), 181–200, DOI: 10.2478/s11533-006-0036-3. Unfortunately, the original version of this article contains a mistake: in Theorem 5.2 only conditions (i) and (ii) (and not (iii)) are equivalent. We correct the theorem and its proof.
Erweiterungen linearer involutorischer Halbgruppen
Every braid admits a short sigma-definite expression
A result by Dehornoy (1992) says that every nontrivial braid admits a -definite expression, defined as a braid word in which the generator with maximal index appears with exponents that are all positive, or all negative. This is the ground result for ordering braids. In this paper, we enhance this result and prove that every braid admits a -definite word expression that, in addition, is quasi-geodesic. This establishes a longstanding conjecture. Our proof uses the dual braid monoid and a new...
Every -variety satisfying the amalgamation property is representable
Every uniformly Archimedean atomic MV-effect algebra is sharply dominating
Following the study of sharp domination in effect algebras, in particular, in atomic Archimedean MV-effect algebras it is proved that if an atomic MV-effect algebra is uniformly Archimedean then it is sharply dominating.
Existence of joins and meets in the partially ordered family of CM-homomorphisms.
Extensions archimédiennes de groupes réticulés transitifs
Extensions of dimension groups and AF C*-algebras.
Extensions of group retractions.
Extensions of ordered semigroups.
Extensions of ordered semigroups
Extensions of ordered semigroups
Extensions of partially ordered partial abelian monoids
The notion of a partially ordered partial abelian monoid is introduced and extensions of partially ordered abelian monoids by partially ordered abelian groups are studied. Conditions for the extensions to exist are found. The cases when both the above mentioned structures have the Riesz decomposition property, or are lattice ordered, are treated. Some applications to effect algebras and MV-algebras are shown.
Extensions of positive operators and extreme points. I