Oberseminar Geometrie und Topologie
The seminar takes place on Wednesday, 16:15 in room B039.
This semester, the talks and speakers are (dates may change!):
- 24.10.2018: Alexander Lytchak (Universität Köln):
"Uniformization of singular surfaces".
- 31.10.2018: No talk
14.11.2018 Reserved for working group seminar
- 5.12.2018: Stefan Wenger (University of Fribourg): Constructing Hölder maps to Carnot groups.
Carnot groups equipped with a Carnot metric are subriemannian
manifolds. These exhibit interesting (local) geometry that is far from
Euclidean. In this talk we mainly focus on the special case of the first
Heisenberg group H and study its geometry through Hölder mappings. By
a theorem of Züst, which strengthens a result of Gromov and Pansu, every
$\alpha$-H├Âlder map with $\alpha>2/3$ from a Euclidean ball to $H$
factors through some tree. We show that Züst's result is sharp by
constructing topologically non-trivial $\alpha$-Hölder maps from the
Euclidean $2$-ball and $3$-ball to $H$ for every $\alpha<2/3$. Some of
our results generalize to general Carnot groups. Joint work with Robert
- 12.12.2018: Jan Swoboda (LMU):
Geometrie und Analysis von Higgsbündel-Modulräumen (Habilitationsvortrag)
- 19.12.2018: No talk
- 9.1.2019: No talk
- 16.1.2019: No talk
- 23.1.2019: Camille Horbez (Orsay): Growth under automorphisms of hyperbolic groups.
Let G be a finitely generated group, let S be a finite generating set of G, and let f be an automorphism of G. A natural question is the following: what are the possible asymptotic behaviours for the length of fn(g) written as a word in the generating set S, as n goes to infinity, and as g varies in the group G? Growth was described by Thurston when G is the fundamental group of a hyperbolic surface, and can be understood from Bestvina-Handel's work on train-tracks when G is a free group. We investigate the case of a general torsion-free hyperbolic group. This is a joint work with Rémi Coulon, Arnaud Hilion, and Gilbert Levitt.
- 30.1.2019: open slot
- 6.2.2019: Tara Brendle (Glasgow)