Hauptseminar Geometrie

Finite rank median spaces simultaneously generalise real trees and finite dimensional CAT(0) cube complexes. Requiring a group to act on a finite rank median space is in general much more restrictive than only asking for an action on a general median space. This is particularly evident for certain irreducible lattices in products of rank-one simple Lie groups: they admit proper cocompact actions on infinite rank median spaces, but any action on a (complete, connected) finite rank median space must fix a point. Our proof of the latter fact is based on a generalisation of a superrigidity result of Chatterji-Fernós-Iozzi. We will sketch the necessary techniques, focussing on some intriguing similarities between horofunction compactifications of median spaces and Satake compactifications of symmetric spaces

Donnerstag, den 13. Dezember 2018 um 12:45 Uhr, in INF205, SR3 Donnerstag, den 13. Dezember 2018 at 12:45, in INF205, SR3

Der Vortrag folgt der Einladung von The lecture takes place at invitation by Prof. Dr. Anna Wienhard