We study finitely generated Heyting algebras from algebraic and model theoretic points of view. We prove amon others that finitely generated free Heyting algebras embed in their profinite completions, which are projective limits of finitely generated free Heyting algebras of finite dimension.

The following definition is an example of defining things by mapping properties, that is, by the way the object relates to other objects, rather than by internal structure. The first proposition, which says that there is at most one such thing, is typical, as is its proof. Let R be a commutative ring with 1. Let S be a set. A free R-moduleM on generators S is an R-module M and a set map i : S →...

Let $R$ be a commutative ring. In this paper we assert some properties of finitely generated comultiplication modules and Fitting ideals of them.

Checking the admissibility of quasiequations in a finitely generated (i.e., generated by a finite set of finite algebras) quasivariety Q amounts to checking validity in a suitable finite free algebra of the quasivariety, and is therefore decidable. However, since free algebras may be large even for small sets of small algebras and very few generators, this naive method for checking admissibilit...

One-generated commutative division semirings are found. The aim of this (partially expository) note is to find all one-generated (commutative) division semirings (see Theorem 8.5). In particular, all such semirings turn out to be finite. To achieve this goal, we have to correct some results from [1] (especially Proposition 12.1 of [1]) and to complete some results from [2]. Anyway, all the pres...

of the Dissertation Combinatorics of Finitely Generated Groups