Resumen

Roughly, a group G is stable if any approximate representation (i.e. a map into a unitary group that comes close to satisfying the representations defining the group) is itself close to an honest representation.

If 'close' is interpreted in terms of the operator norm, this is known to be obstructed by K-theoretic invariants: this goes back to work of Voiculescu and Kazhdan in the 1980s for Z^2 and other fundamental groups of surfaces, and is now known to hold quite broadly thanks to work of Eilers-Shulman-Sørensen, Dadarlat, and others.

In this talk, I'll briefly survey some examples of this, and then explain some situations where one can show stability conditional on vanishing of the known K-theoretic obstructions.

Este seminario, abierto a todo el público interesado, es organizado por los miembros del grupo de Geometría No Conmutativa. Las reuniones son los martes a las 10:00hs, vía Zoom (para recibir las coordenadas escribir a gtartaglia arroba mate.unlp.edu.ar)

Página del seminario: https://cms.dm.uba.ar/Members/gcorti/workgroup.GNC/GeNoCAS_seminar