Workshop 1 - Operator Algebras: Groups and Dynamics

28 sept. 2026, 08:30 → 2 oct. 2026, 17:30 Europe/Paris

Amphithéâtre Hermite (Institut Henri Poincaré)

Operator Algebras: Approximation, Rigidity and Dynamics.

Workshop 1 - Operator Algebras: Groups and Dynamics

September 28 to October 2, 2026 - IHP, Paris

Summary

The workshop will feature talks on the latest developments on the interaction between operators algebras, group representation theory, group actions, topological dynamics and ergodic theory.

List of speakers:

• Goulnara Arzhantseva 
• Uri Bader 
• Emmanuel Breuillard 
• Pierre-Emmanuel Caprace 
• David Fisher 
• Shirly Geffen 
• Ursula Hamenstädt 
• Adrian Ioana 
• Mehrdad Kalantar 
• Fanny Kassel  
• Corentin Le Bars
• Waltraud Lederle 
• Arie Levit
• Simon Machado 
• Hanna Oppelmayer 
• Denis Osin 
• Sven Raum
• Yehuda Shalom 
• Itamar Vigdorovich 
• Tianyi Zheng

Organising Committee:

• Camille Horbez
• Cyril Houdayer
• Corentin Le Bars 

schedule_workshop1.pdf

lun. 28 septembre

09:30 → 10:00 Welcome Coffee/ Badge Distribution

10:00 → 10:10 Opening Speech by IHP's Deputy Director, Prof. Mariana Grana

10:10 → 10:55 Uri Bader: How to get infected with Lp-cohomology and how to cure it?

10:55 → 11:15 Coffee break

11:15 → 12:00 Simon Machado: Quantitative growth of the injectivity radius

12:00 → 14:00 Lunch

14:00 → 14:45 Adrian Ioana: Rigidity for graph product von Neumann algebras

14:45 → 15:15 Coffee break

15:15 → 16:00 Ursula Hamenstädt: Mixing and counting in relatively hyperbolic groups

16:15 → 17:00 Hanna Oppelmayer: Random subalgebras

mar. 29 septembre

10:00 → 10:45 Emmanuel Breuillard

10:45 → 11:15 Coffee break

11:15 → 12:00 Tianyi Zheng: Commensurating actions and the Sierpiński carpet group

12:00 → 12:10 Group Photo

12:10 → 14:00 Lunch

14:00 → 14:45 Yehuda Shalom

14:45 → 15:15 Coffee break

15:15 → 16:00 Goulnara Arzhantseva: Simple and selfless reduced group C*-algebras

16:15 → 17:00 Corentin Le Bars: Charmenability of twin-building lattices

18:00 → 20:30 Cocktail

mer. 30 septembre

09:30 → 10:15 Pierre-Emmanuel Caprace: Mixing versus amenability for unitary representations of groups acting on buildings

10:15 → 10:45 Coffee break

10:45 → 11:30 Denis Osin: A paradoxical route from hyperbolic geometry to proper proximality

11:30 → 12:15 Shirly Geffen: Stable rank one in nonnuclear C*-algebras

jeu. 1 octobre

10:00 → 10:45 Waltraud Lederle: Boomerang subgroups, Schreier graphs and avoiding invariant measures

10:45 → 11:15 Coffee break

11:15 → 12:00 Mehrdad Kalantar: On Invariant Random Subgroups of C*-Simple Groups

12:00 → 14:00 Lunch

14:00 → 14:45 Sven Raum: K-theory and delocalised traces of right-angled Hecke C*-algebras

14:45 → 15:15 Coffee break

15:15 → 16:00 Itamar Vigdorovich: Selfless reduced group C*-algebras

16:15 → 17:00 Arie Levit: Invariant random subgroups of the finitary special linear group over a finite field

ven. 2 octobre

10:00 → 10:45 Fanny Kassel: Anosov representations and compact quotients

10:45 → 11:15 Coffee break

11:15 → 12:00 David Fisher: Dense subgroups of compact groups: two vignettes