# Bonn Topology Group - Abstracts

General Information - Members - Activities - Topology Seminar

### Talk

April 16th 2019

Giles Gardam (WWU Münster):
Boundaries of hyperbolic and CAT(0) groups and Cannon-Thurston maps.

### Abstract

A fundamental invariant in the study of hyperbolic groups is their boundaries.
The classical Cannon-Thurston map for a closed fibered hyperbolic 3-manifolds relates two such boundaries: It gives a continuous surjection from the boundary of the surface group
(a circle) to the boundary of the 3-manifold group (a 2-sphere). Mitra generalized this to all hyperbolic groups with hyperbolic normal subgroups.
I will explain why such a generalization to CAT(0) groups with the visual boundary is impossible.

Joint work with Beeker-Cordes-Gupta-Stark.

Back to seminar page

## News

04.11.24: Hirzebruch lecture by Lisa Sauermann

Gerd Faltings elected member of the Order Pour le MÃ©rite

Geordie Williamson receives the Max Planck-Humboldt Research Award 2024

ERC Starting Grant for Markus Hausmann

EMS Prize 2024 for Jessica Fintzen

Bonn mathematics performs excellently again in QS ranking

Stefan Schwede is invited speaker at the ECM 2024 in Sevilla

Jessica Fintzen wins Cole Prize

Catharina Stroppel receives Gottfried Wilhelm Leibniz Prize 2023

Jessica Fintzen is awarded a Whitehead Prize of the London Mathematical Society

Peter Scholze elected as Foreign Member of the Royal Society