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Accueil > Séminaires > Analyse Fonctionnelle

## Séminaire d’Analyse Fonctionnelle

Le séminaire a lieu le mardi à 13h45, en salle 316Bbis du bâtiment de
Métrologie (plan d’accès).

Vous trouverez ci-dessous le planning du séminaire d’Analyse
Fonctionnelle pour l’année universitaire en cours.
L’historique des séminaires des années précédentes se trouve
ici.

Pour contacter le responsable (Tony Prochazka) : antonin.prochazka univ-fcomte.fr.
Pour s’abonner au séminaire : ACM.

### Exposés à venir

-Mardi 4 novembre: Adam Skalski, IMPAN Varsovie.

How noncommutative is noncommutative topological entropy?

The notion of noncommutative topological entropy for automorphisms of (nuclear) C*-algebras was introduced in 1995 by D. Voiculescu as a generalisation of the topological entropy for continuous transformations of compact spaces. I will explain some of the properties of the Voiculescu entropy and discuss examples showing that the connections between the commutative and noncommutative case are actually quite subtle (partly based on joint work with Joachim Zacharias).

-Mardi 11 novembre: Relâche, Armistice.

-Mardi 18 novembre: Michal Kraus, Czech Academy of Sciences.

Hilbert space compression exponent of quasi-Banach spaces

-Mardi 25 novembre: Piotr M. Hajac, IMPAN Varsovie.

Free actions of compact quantum groups on unital C*-algebras

Let F be a field, G a finite group, and Map(G,F) the Hopf algebra of all set-theoretic maps G -> F. If E is a finite field extension of F and G is its Galois group, the extension is Galois if and only if the canonical map resulting from viewing E as a Map(G,F)-comodule is an isomorphism. Similarly, a finite covering space is regular if and only if the analogous canonical map is an isomorphism. The main result to be presented in this talk is an extension of this point of view to arbitrary actions of compact quantum groups on unital C*-algebras. I will explain that such an action is free (in the sense of Ellwood) if and only if the canonical map (obtained using the underlying Hopf algebra of the compact quantum group) is an isomorphism. In particular, we are able to express the freeness of a compact Hausdorff topological group action on a compact Hausdorff topological space in algebraic terms. Also, we can apply the main result to noncommutative join constructions and coactions of discrete groups on unital C*-algebras. (Joint work with Paul F. Baum and Kenny De Commer.)

-mardi 25 novembre à 15h30: Pierre Pansu, .

Exposant de Hölder et pincement de la courbure

Est-ce qu'il existe un homéomorphisme $\alpha$-Hölder continu de l'espace euclidien sur le groupe d'Heisenberg, avec $\alpha >1/2$ ? On étudie une question voisine, motivée par un problème de géométrie riemannienne (meilleur pincement de la courbure pour une variété riemannienne quasi-isométrique à un espace symétrique de rang un).

Octobre

-Mardi 7 octobre: Marat Aukhadiev, Kazan State Power Engineering University.

On a category of compact quantum semigroups

-Mardi 14 octobre: Relâche, Journées de GDR Lille.

-Mardi 21 octobre: Zhengwei Liu, Vanderbilt University.

Noncommutative uncertainty principles

-Mardi 28 octobre: Relâche, Trimestres LMB.

Conference on Geometric functional analysis and its Applications

Septembre

-Mardi 9 septembre: Fedor Sukochev, University of New South Wales.

Invariant subspaces and upper triangular forms for classes of infinite dimensional operators.

In classical matrix theory, a matrix can be written in upper triangular form with help of its invariant subspaces. A similar result, due to Ringrose in 1962, holds for compact operators on infinite dimensional Hilbert space. Using recent results of Haagerup and Schultz, we prove an analogous result for certain non-compact operators on Hilbert space, namely, for those in finite von Neumann algebras. The talk may also include some new results concerning triangular form of unbounded operators affiliated with finite von Neumann algebras and some speculation about invariant subspace problems for elements of finite von Neumann algebras. (Joint work with Ken Dykema and Dmitriy Zanin).
slides

-Mardi 16 septembre: Jean Roydor, Université Bordeaux.

Perturbations d'algèbres d'opérateurs

-Mardi 23 septembre: Pierre Portal, Australian National University et Université Lille 1.

Régularité maximale conique

-Mardi 30 septembre: Relâche, Trimestres LMB.

Functional calculus and Harmonic analysis of semigroups