Ulam stability of Thompson groups

Franceso Fournier-Facio (ETH Zurich)

Jul 18. 2023, 14:50 — 15:30

Ulam stability is a rigidity property for discrete groups that can be informally stated as: all approximate (finite-dimensional unitary) representations are just small perturbations of true representations. Glebsky-Lubotzky-Monod-Rangarajan recently proved Ulam stability of (almost) all lattices in higher rank Lie groups. Their proof introduces a new cohomology theory, called asymptotic cohomology, which can be seen as a nonstandard-analytic version of bounded cohomology. I will give a brief informal introduction to asymptotic cohomology, and explain how it can also be used to prove Ulam stability of Thompson's groups F, T and V. This is joint work with Bharatram Rangarajan.

Further Information
ESI Schrödinger and Boltzmann Lecture Hall
Associated Event:
Geometric and Asymptotic Group Theory with Applications 2023 - Groups and Dynamics (Workshop)
Christopher Cashen (U of Vienna)
Javier de la Nuez González (KIAS, Seoul)
Alexandra Edletzberger (U of Vienna)
Yash Lodha (U of Hawaii, Honolulu)