Tea Seminar of our group

Place and time:

Semester:		Summer term 2026
Zeit:		Tue 10:15 - 11:15
Ort:		SR 1B

Inhalt:

In this seminar, guests and members of our group present their research, or topics of interest to us. Presently we use a hybrid format for the seminar (in-person and zoom). In case you are interested, please contact Raquel Murat.

Talks:

16.06.2026 Miguel Gentili (Münster) The bounded cohomology of the transformation groups of Euclidean spaces.

Abstract: Bounded cohomology is a functional-analytic variant of ordinary cohomology with applications in the study of manifold geometry, rigidity theory, ergodic theory, and many other areas. The aim of this talk is to discuss a result concerning the vanishing of the bounded cohomology of the transformation groups of Euclidean spaces.
To this end, we will first recall the definition of (bounded) cohomology of groups, along with its main properties and key results. We will then briefly review the notion of amenability and explore its connection with bounded cohomology.
We will then focus on the aforementioned result. We will begin with the group of homeomorphisms of R^n with compact support, as treated by Matsumoto and Morita in 1985, and then turn on the full groups of all the homeomorphisms and diffeomorphisms of Euclidean spaces. The latter result is recent and is due to Fournier-Facio, Monod, and Nariman (2024). Quite surprisingly, in both cases the bounded cohomology vanishes, although the techniques employed are substantially different.

23.06.2026 Pia Dillmann (Münster) Existence results for compact homogeneous Einstein spaces.

Abstract: I will speak on the classification problem of compact homogeneous Einstein spaces G/H. Recall that a G-invariant Einstein metric can be characterized as a critical point of the scalar curvature function restricted to the space of G-invariant metrics of volume one. To this end, I will introduce a new simplicial complex (defined by certain intermediate subgroups H<K<G) whose non-contractability yields such an existence result.

30.06.2026 Markus Stroppel (Stuttgart) Pleasant surprises: exceptional isomorphisms.

Abstract: Roughly speaking, the classical groups are groups of linear bijections of vector spaces over division rings, and subgroups singled out by requiring that some form (quadratic, bilinear, hermitian) be invariant. So each one of those groups is determined by some recipe, and some ingredients (a division ring, a number, a form, ...). E.g., a famous recipe named "A" takes a division ring K and a number n to produce the group SL(n,K), along with its relatives GL(n,K), PSL(n,K). Another recipe (no name given) takes a field R, a number n, and a non-degenerate quadratic form of Witt index i in n variables from R to produce the corresponding group of isometries.
Conversely, the produced group determines the recipe and its ingredients, in general. However, there are some exceptions, including the reason why physicists study SL(2,C) while doing special relativity.
The talk will report about such exceptions, and ways to understand deeper reasons for their occurrence.

02.07.2026 Bianca Firmbach (Münster) On the Uniqueness of the Topology of SL2(Qp). Room SR 1D

Abstract: A central question in the theory of automatic continuity is whether the topology of a topological group is uniquely determined by its algebraic structure. My PhD project investigates this question in the setting of p-adic Lie groups. In this talk, I will discuss the group SL2(Qp) as a first example. We will see that SL2(Qp) admits a unique topology, and I will outline the strategy used to prove this result.