Search results for "Versa"

On almost nilpotent varieties of subexponential growth

2015

Abstract Let N 2 be the variety of left-nilpotent algebras of index two, that is the variety of algebras satisfying the identity x ( y z ) ≡ 0 . We introduce two new varieties, denoted by V sym and V alt , contained in the variety N 2 and we prove that V sym and V alt are the only two varieties almost nilpotent of subexponential growth.

Characterizing varieties of colength ≤4

2009

Let A be an associative algebra over a field F of characteristic zero, and let χ n (A), n = 1,2,…, be the sequence of cocharacters of A. For every n ≥ 1, let l n (A) denote the nth colength of A, counting the number of S n -irreducibles appearing in χ n (A). In this article, we classify the algebras A such that the sequence of colengths l n (A), n = 1,2,…, is bounded by four. Moreover we construct a finite number of algebras A 1,…, A d , such that l n (A) ≤ 4 if and only if A 1,…, A d  ∉ var(A).

Varieties of superalgebras of almost polynomial growth

2011

Abstract Let V gr be a variety of superalgebras and let c n gr ( V gr ) , n = 1 , 2 , …  , be its sequence of graded codimensions. Such a sequence is polynomially bounded if and only if V gr does not contain a list of five superalgebras consisting of a commutative superalgebra, the infinite dimensional Grassmann algebra and the algebra of 2 × 2 upper triangular matrices with trivial and natural Z 2 -gradings. In this paper we completely classify all subvarieties of the varieties generated by these five superalgebras, by giving a complete list of finite dimensional generating superalgebras.

Partial Finitely Generated Bi-Ideals

2016

Partial words have been studied by Blanchet-Sadri et al., but bi-ideals or reccurrent words have been studied for centuries by many researchers. This paper gives a solution for some problems for partial reccurrent words. This paper gives an algorithm for a given finitely generated bi-ideal, how to construct a new basis of ultimately finitely generated bi-ideal, which generates the same given bi-ideal. The paper states that it is always possible to find a basis for a given finitely generated bi-ideal. The main results of this paper are presented in third section. At first, we show that if two irreduciable bi-ideals are different, they will differ in infinitely many places. This led to the st…

Finitary Representations and Images of Transitive Finitary Permutation Groups

1999

Abstract We characterize the point stabilizers and kernels of finitary permutation representations of infinite transitive groups of finitary permutations. Moreover, the number of such representations is determined.

Le tecnologie utilizzate negli impianti di dissalazione

2009

Guided local search for the optimal communication spanning tree problem

2011

This paper considers the optimal communication spanning tree (OCST) problem. Previous work analyzed features of high-quality solutions. Consequently, integrating this knowledge into a metaheuristic increases its performance for the OCST problem. In this paper, we present a guided local search (GLS) approach which dynamically changes the objective function to guide the search process into promising areas. In contrast to traditional approaches which reward promising solution features by favoring edges with low weights pointing towards the tree's center, GLS penalizes low-quality edges with large weights that do not point towards the tree's center.

Plural Paths for Interweaving Diversity in Palermo

2008

The most recent ethnic movements and cultural contacts are modifying the city nature all over the world, and in these years even the most fringe European areas are witnessing an increase in cultural and social mixité. Currently we can assert that the city is not an unitary system any more, instead is composed of multiple (often non-homogeneous) groups which express new forms and demands of space use. In this context of fast changes, the various ethnic groups coming to European cities are not the only stakeholders of diversity. There are also cultural groups which have remained separate until now, each one rooted in a restricted part of the city, according to models that are obsolete nowaday…

Un biais d'estimation de la rentabilité de l'éducation dans le modèle de gains de Mincer appliqué à des données transversales

1986

First Measurement of Transverse-Spin-Dependent Azimuthal Asymmetries in the Drell-Yan Process

2017

The first measurement of transverse-spin-dependent azimuthal asymmetries in the pion-induced Drell-Yan (DY) process is reported. We use the CERN SPS 190 GeV/$c$, $\pi^{-}$ beam and a transversely polarized ammonia target. Three azimuthal asymmetries giving access to different transverse-momentum-dependent (TMD) parton distribution functions (PDFs) are extracted using dimuon events with invariant mass between 4.3 GeV/$c^2$ and 8.5 GeV/$c^2$. The observed sign of the Sivers asymmetry is found to be consistent with the fundamental prediction of Quantum Chromodynamics (QCD) that the Sivers TMD PDFs extracted from DY have a sign opposite to the one extracted from semi-inclusive deep-inelastic sc…