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Polynomial identities of nil algebras of bounded index

Francesca Benanti, Vesselin Drensky (1999)

Bollettino dell'Unione Matematica Italiana

Lo scopo di questo lavoro è di dare una nuova descrizione del T -ideale generato dalla nil-identità x n = 0 come immagine omeomorfa della n -esima potenza tensoriale simmetrica dell'algebra associativa libera K X su un campo K di caratteristica 0 . Come applicazione calcoliamo il carattere delle conseguenze multilineari di grado n + 2 dell'identità x n = 0 .

Posner's second theorem and annihilator conditions with generalized skew derivations

Vincenzo De Filippis, Feng Wei (2012)

Colloquium Mathematicae

Let be a prime ring of characteristic different from 2, r be its right Martindale quotient ring and be its extended centroid. Suppose that is a non-zero generalized skew derivation of and f(x₁,..., xₙ) is a non-central multilinear polynomial over with n non-commuting variables. If there exists a non-zero element a of such that a[ (f(r₁,..., rₙ)),f(r₁, ..., rₙ)] = 0 for all r₁, ..., rₙ ∈ , then one of the following holds: (a) there exists λ ∈ such that (x) = λx for all x ∈ ; (b) there exist q r and...

Power-cancellation of CW-complexes with few cells.

Irene Llerena (1992)

Publicacions Matemàtiques

In this paper we use the fact that the rings of integer matrices have the power-substitution property in order to obtain a power-cancellation property for homotopy types of CW-complexes with one cell in dimensions 0 and 4n and a finite number of cells in dimension 2n.

Precovers

Ladislav Bican, Blas Torrecillas (2003)

Czechoslovak Mathematical Journal

Let 𝒢 be an abstract class (closed under isomorpic copies) of left R -modules. In the first part of the paper some sufficient conditions under which 𝒢 is a precover class are given. The next section studies the 𝒢 -precovers which are 𝒢 -covers. In the final part the results obtained are applied to the hereditary torsion theories on the category on left R -modules. Especially, several sufficient conditions for the existence of σ -torsionfree and σ -torsionfree σ -injective covers are presented.

Precovers and Goldie’s torsion theory

Ladislav Bican (2003)

Mathematica Bohemica

Recently, Rim and Teply , using the notion of τ -exact modules, found a necessary condition for the existence of τ -torsionfree covers with respect to a given hereditary torsion theory τ for the category R -mod of all unitary left R -modules over an associative ring R with identity. Some relations between τ -torsionfree and τ -exact covers have been investigated in . The purpose of this note is to show that if σ = ( 𝒯 σ , σ ) is Goldie’s torsion theory and σ is a precover class, then τ is a precover class whenever...

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