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Folner sets of alternate directed groups

Jérémie Brieussel (2014)

Annales de l’institut Fourier

An explicit family of Folner sets is constructed for some directed groups acting on a rooted tree of sublogarithmic valency by alternate permutations. In the case of bounded valency, these groups were known to be amenable by probabilistic methods. The present construction provides a new and independent proof of amenability, using neither random walks, nor word length.

Fonctions définies dans le plan et vérifiant certaines propriétés de moyenne

Alain Yger (1981)

Annales de l'institut Fourier

Soit a un réel de ] 0 , 1 [ . Nous étudions le système d’équations de convolution suivant ( * ) x R 2 , f ( x ) = 1 4 ϵ = ± 1 ϵ ' = ± 1 f ( x + ( ϵ , ϵ ' ) ) = 1 4 ϵ = ± 1 ϵ ' = ± 1 f ( x + a ( ϵ , ϵ ' ) ) . Nous démontrons que les exponentielles polynômes solutions de ( * ) sont denses dans l’espace des solutions C du système d’équations; l’idéal de ' ( R 2 ) engendré par les transformées de Fourier des deux mesures intervenant ici est “slowly decreasing” au sens de Berenstein-Taylor. Lorsque a n’est pas un nombre de Liouville, nous montrons qu’il existe un ouvert relativement compact telle que toute solution distribution de ( * ) régulière...

Formule de Gutzmer pour la complexification d'une espace Riemannien symétrique

Jacques Faraut (2002)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

A Gutzmer formula for the complexification of a Riemann symmetric space. We consider a complex manifold Ω and a real Lie group G of holomorphic automorphisms of Ω . The question we study is, for a holomorphic function f on Ω , to evaluate the integral of f 2 over a G -orbit by using the harmonic analysis of G . When Ω is an annulus in the complex plane and G the rotation group, it is solved by a classical formula which is sometimes called Gutzmer’s formula. We establish a generalization of it when Ω is...

Fourier analysis, Schur multipliers on S p and non-commutative Λ(p)-sets

Asma Harcharras (1999)

Studia Mathematica

This work deals with various questions concerning Fourier multipliers on L p , Schur multipliers on the Schatten class S p as well as their completely bounded versions when L p and S p are viewed as operator spaces. For this purpose we use subsets of ℤ enjoying the non-commutative Λ(p)-property which is a new analytic property much stronger than the classical Λ(p)-property. We start by studying the notion of non-commutative Λ(p)-sets in the general case of an arbitrary discrete group before turning to the...

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