Invariant Means via the Ultrapower.
Invariant states and a conditional fixed point property for affine actions.
Kazhdan's property (T) and amenable representations.
Left thickness, left amenability and extreme left amenability.
Means of translates
Means of vector-valued functions and projections which commute with the action of a group
Means on -subspaces of with RNP and Schur property
Let be a locally compact abelian group and be the space of bounded convolution...
Means with values in a Banach lattice.
Measurable functionals on function spaces
We prove that all measurable functionals on certain function spaces are measures; this improves the (known) results about weak sequential completeness of spaces of measures. As an application, we prove several results of this form: if the space of invariant functionals on a function space is separable then every invariant functional is a measure.
Medias en espacios localmente convexos y semi-reflexivilidad.
Medias generalizadas y aplicaciones.
Mittelergodische Halbgruppen linearer Operatoren
A semigroup in , a Banach space, is called mean ergodic, if its closed convex hull in has a zero element. Compact groups, compact abelian semigroups or contractive semigroups on Hilbert spaces are mean ergodic.Banach lattices prove to be a natural frame for further mean ergodic theorems: let be a bounded semigroup of positive operators on a Banach lattice with order continuous norm. is mean ergodic if there is a -subinvariant quasi-interior point of and a -subinvariant strictly...
Module -amenability of Banach algebras
Let be an inverse semigroup with the set of idempotents and be an appropriate group homomorphic image of . In this paper we find a one-to-one correspondence between two cohomology groups of the group algebra and the semigroup algebra with coefficients in the same space. As a consequence, we prove that is amenable if and only if is amenable. This could be considered as the same result of Duncan and Namioka [5] with another method which asserts that the inverse semigroup is amenable...
More on the Kechris-Pestov-Todorcevic correspondence: Precompact expansions
In 2005, the paper [KPT05] by Kechris, Pestov and Todorcevic provided a powerful tool to compute an invariant of topological groups known as the universal minimal flow. This immediately led to an explicit representation of this invariant in many concrete cases. However, in some particular situations, the framework of [KPT05] does not allow one to perform the computation directly, but only after a slight modification of the original argument. The purpose of the present paper is to supplement [KPT05]...
Moyennabilité intérieure et extensions HNN
On présente des conditions suffisantes pour qu’une extension HNN soit intérieurement moyennable, respectivement CCI, qui donnent des critères nécessaires et suffisants parmi les groupes de Baumslag-Solitar. On en déduit qu’un tel groupe, vu comme groupe d’automorphismes de son arbre de Bass-Serre, possède des éléments non triviaux qui fixent des sous-arbres non bornés.
Moyennes invariantes s'annulant sur des idéaux
Moyennes sphériques et opérateur de Helmholtz itéré
Il est bien connu qu’une fonction sur est harmonique - Δf = 0 - si et seulement si sa moyenne sur toute sphère est égale à sa valeur au centre de cette sphère. De manière semblable, f vérifie l’équation de Helmholtz Δf + cf = 0 si et seulement si sa moyenne sur la sphère de centre x et de rayon r vaut . Dans ce travail, nous généralisons ces résultats à l’opérateur où k est un entier strictement positif et c une constante non nulle. Bien qu’une méthode pour y parvenir soit esquissée dans...
Multipliers on , and for a locally compact topological semigroup.
New a-T-menable HNN-extensions.
Non Uniqueness of Invariant Means for Amenable Group Actions.