Arbre de Noel de Géométrie non commutative (AdN)

Liste des Contributions

1. Eva-Maria Hekkelman

17/12/2025 14:00

5. Pierre Martinetti

17/12/2025 15:00

6. Christelle Gebara: Nonparabolic Γ-near innity operators

17/12/2025 16:00

In this talk we will first introduce the notion of NΓ-Hilbert space as introduced by Wolfgang Lück in 1997. Then, we will introduce the notion of Γ-Fredholm operators defined between N Γ-Hilbert space. And finally, the goal of the presentation is to define nonparabolic Γ-near infinity operators and show how they induces Γ-Fredholmness on admissible domains

7. Kai Mao: A going-down principle fo étale groupoids and Baum-Connes conjecture

17/12/2025 16:35

Using a going-down principle, Chabert, Echterhoff and Oyono-Oyono proved the injectivity of the assembly map for locally compact Hausdorff groups that are amenable at infinity. Bönicke proved the analogue for ample groupoids. In this talk we present the proof of the going-down principle for étale groupoids in general. It yields the injectivity of the assembly map for étale groupoids that are...

8. Yvann Gaudillot-Estrada: The quantum Mackey analogy by examples

17/12/2025 17:10

We present two distinct deformations of a given semisimple Lie group: the contraction onto the motion group, knwon as the Mackey-Higson deformation, and the quantisation of the symmetric pair related to a maximal compact subgroup, due to Letzter.
For low dimensional examples, we explain how to assemble these two deformations into a continuous field of C*-algebras defined over a square, which...

9. Quentin Karegar

17/12/2025 17:45

2. Jean Renault: Sous-algèbres de Cartan dans les C*-algèbres.

18/12/2025 09:00

Dans mon premier exposé, je présenterai le cadre usuel de la théorie.
Dans le deuxième exposé, je présenterai des développements plus récents concernant l’existence de sous-algèbres de Cartan dans les C-algèbres nucléaires, les C-algèbres de groupoides non effectifs et les
C*-algèbres de groupoides non séparés.

10. Estelle Boffy: 20Positive and Contractive Projections on Schatten spaces

18/12/2025 10:00

A subspace of a Banach space E is said to be 1-complemented if it is the ra=
nge of a contractive projection, and positively 1-complemented if the proje=
ction is, in addition, positive. In the commutative Lp spaces, the descript=
ion of contractive projections is well known (see, e.g., Ando's Theorem, 19=
66). In 1992, Arazy and Friedman provided a characterization of the...

11. Michel Hilsum: Affine Kazdhan group actions on Schatten Ideals and Fixed point property.

18/12/2025 11:00

We shall review basics facts about group actions on Banach spaces by affine isometries and explain latest result concerning the case of Schatten ideals.

12. Patrick Poissel: A general pushforward theorem for compactly supported Fourier multipliers

18/12/2025 11:30

To any sufficiently regular distribution $m$ on a locally compact group is associated, by the mean of the Fourier transform, some sort of « differential operator with symbol $m$ » on the dual of this group which in general is merely a quantum group. In 1970, M. Jodeit Jr. has shown that if a compactly supported distribution on $\mathbf R^d$ is the symbol of a continuous linear operator from...

3. Eva-Maria Hekkelman

18/12/2025 14:00

13. Cedric Arhancet: Classical harmonic analysis viewed through the prism of noncommutative geometry

18/12/2025 15:00

This talk aims to connect noncommutative geometry with classical harmonic analysis on Banach spaces, with a particular emphasis on both classical and noncommutative Lp-spaces. The overarching goal is to show how the study of operators on Lp-spaces can be naturally integrated into the broader framework of noncommutative geometry, thereby opening new perspectives in...

14. Thibault Lescure: A noncommutative compactification of Bass-Serre Trees

18/12/2025 16:00

When a group G acts properly on a tree T, it is a classical result that the action of G on the Gromov compactification X of the tree is amenable, i.e. the crossed product C(X)xG is nuclear. We will introduce an analogue of the crossed product C-algebra C(X)xG in the context of fundamental C-algebras of graph of C-algebras (Fima,Freslon 2013). This C-algebra has interesting features...

15. Leandre Portela

18/12/2025 16:35

16. Axel Gastaldi: Banach Dirac-Dual Dirac method for periodic cyclic homology

18/12/2025 17:10

The aim of this talk is to provides a natural identification between crossed product algebras with respect to a Lie group $G$ and to a maximal compact subgroup $K < G$, extending globally a result of V. Nistor stated in the early 90's. We develop Banach-analytic analogue of the Cuntz's approach to bivariant K-theory, and we adapt the Dirac-dual Dirac method for periodic cyclic homology. As a...

4. Jean Renault

19/12/2025 09:00

17. Yigang Qiu

19/12/2025 10:00

18. Albert Nebout

19/12/2025 11:00

19. Axel Saglio

19/12/2025 11:30