Weakly regular algebras in varieties with principal compact congruences Ivan Chajda. Weakly regular algebras in varieties with principal compact congruences. Institute of Mathematics, Academy of Sciences of the Czech Republic, provides access to digitized documents strictly for personal use. Each copy of any part of this document must contain these Terms of use. This paper has been digitized, o...

An algebra A is said to be congruence coherent if every subalgebra of A that contains a class of some congruence θ on A is a union of θ-classes. This property has been investigated in several varieties of lattice-based algebras. These include, for example, de Morgan algebras, p-algebras, double p-algebras, and double MS-algebras. Here we determine precisely when the property holds in the class ...

This paper addresses the question for which varieties of boolean algebras with operators membership of an atomic algebra A is determined by its atom structure AtA. We prove a positive answer for conjugated Sahlqvist varieties; we also show that the conjugation condition is necessary. As a corollary to the positive result and a recent result by I. Hodkinson, we prove that the variety RRA of repr...

We investigate commutator operations on compatible uniformities. We present a commutator operation for uniformities in the congruence-modular case which extends the commutator on congruences, and explore its properties. Introduction The purpose of this paper is to generalize the commutator of congruences to a commutator of compatible uniformities. Commutator theory (on congruences) works best f...

The variety \(\mathbb{DHMSH}\) of dually hemimorphic semi-Heyting algebras was introduced in 2011 by the second author as an expansion a dual hemimorphism. In this paper, we focus on from logical point view. paper presents extensive investigation logic corresponding to and its axiomatic extensions, along with equally universal algebraic study their semantics. Firstly, present Hilbert-style axio...

The last decade has seen two methodological advances of particular direct import for the theory of nite monoids and indirect import for that of rational languages. The rst has been the use of categories (considered as \algebras over graphs") as a framework in which to study monoids and their homomorphisms, the second has been the use of implicit operations to study pseudovarieties of monoids. S...

We use theorems of N. Karpenko about the incompressibility of Severi Brauer varieties and quadratic Weil transfers of Severi Brauer varieties to compute the minimal number of parameters needed to define conjugacy classes of involutions of given type on division algebras of 2-primary index. Similarly we compute the minimal number of parameters needed to define conjugacy classes of étale subalgeb...