Search results for "General Mathematics"
showing 10 items of 3795 documents
A? * algebra of pseudodifferential operators on noncompact manifolds
1988
On montre qu'une classe d'operateurs pseudodifferentiels d'ordre zero a la propriete d'invariance spectrale
On a theorem of Berkovich
2002
In a recent paper, Berkovich studied how to describe the nilpotent residual of a group in terms of the nilpotent residuals of some of its subgroups. That study required the knowledge of the structure of the minimal nonnilpotent groups, also called Schmidt groups. The major aim of this paper is to show that this description could be obtained as a consequence of a more complete property, giving birth to some interesting generalizations. This purpose naturally led us to the study of a family of subgroup-closed saturated formations of nilpotent type. An innovative approach to these classes is provided.
Polish G-spaces and continuous logic
2017
Abstract We extend the generalised model theory of H. Becker from [2] to the case of Polish G -spaces when G is an arbitrary Polish group. Our approach is inspired by logic actions of Polish groups which arise in continuous logic.
A note on quarkonial systems and multilevel partition of unity methods
2013
We discuss the connection between the theory of quarkonial decompositions for function spaces developed by Hans Triebel, and the multilevel partition of unity method. The central result is an alternative approach to the stability of quarkonial decompositions in Besov spaces , s > n(1/p − 1)+, which leads to relaxed decay assumptions on the elements of a quarkonial system as the monomial degree grows.
Birkhoff-Frink representations as functors
2010
In an earlier article we characterized, from the viewpoint of set theory, those closure operators for which the classical result of Birkhoff and Frink, stating the equivalence between algebraic closure spaces, subalgebra lattices and algebraic lattices, holds in a many-sorted setting. In the present article we investigate, from the standpoint of category theory, the form these equivalences take when the adequate morphisms of the several different species of structures implicated in them are also taken into account. Specifically, our main aim is to provide a functorial rendering of the Birkhoff-Frink representation theorems for both single-sorted algebras and many-sorted algebras, by definin…
GEOMETRIC EQUIVALENCE OF ALGEBRAS
2001
In this paper, we study the geometric equivalence of algebras in several varieties of algebras. We solve some of the problems formulated in [2], in particular, that of geometric equivalence for real-closed fields and finitely generated commutative groups.
Erratum to “Separation of representations with quadratic overgroups” [Bull. Sci. Math. 135 (2) (2011) 141–165]
2011
Abstract In the paper entitled “Separation of representations with quadratic overgroups”, we defined the notion of quadratic overgroups, and announced that the 6-dimensional nilpotent Lie algebra g 6 , 20 admits such a quadratic overgroup. There is a mistake in the proof. The present Erratum explains that the proposed overgroup is only weakly quadratic, and g 6 , 20 does not admit any natural quadratic overgroup.
Inducing characters and nilpotent injectors
2000
Let G be a finite group and let N be a normal subgroup of G. If G/N is solvable and H/N is a nilpotent injector of G/N, then there exists a canonical basis of the complex space of the class functions of G which vanish off the G-conjugates of H.
Nilpotent and abelian Hall subgroups in finite groups
2015
[EN] We give a characterization of the finite groups having nilpotent or abelian Hall pi-subgroups that can easily be verified using the character table.