## Welcome to SPP 2026

This is the platform of a coordinated research programme in mathematics, funded by the German Research Foundation (DFG). It comprises 33 research projects in the fields of differential geometry, geometric topology, and global analysis. More than 80 researchers from doctoral to professorial level and based at more than 20 German and Swiss universities are represented in this programme.

## Next Activities

## Latest publications

#### The Baum--Connes conjecture localised at the unit element of a discrete group

Paolo Antonini, Sara Azzali, Georges Skandalis

We construct a Baum--Connes assembly map localised at the unit element of a discrete group $\Gamma$.

This morphism, called $\mu_\tau$, is defined in...

#### Conic manifolds under the Yamabe flow

Nikolaos Roidos

We consider the unnormalized Yamabe flow on manifolds with conical singularities. Under certain geometric assumption on the initial cross-section we...

#### S-arithmetic spinor groups with the same finite quotients and distinct ℓ²-cohomology

Holger Kammeyer, Roman Sauer

In this note we refine examples by Aka from arithmetic to S-arithmetic groups to show that the vanishing of the *i*-th ℓ²-Betti number is not a...

#### Profinite commensurability of S-arithmetic groups

Holger Kammeyer

Given an S-arithmetic group, we ask how much information on the ambient algebraic group, number field of definition, and set of places S is encoded in...

## Latest Blog posts

**Prizes, prizes, prizes**Several prizes have been awarded in the past few weeks to mathematicians. Kyoto Prize The Kyoto Prize 2018 in the category Basic Sciences was awarded to Masaki Kashiwara from the RIMS at Kyoto University. (announcement) The Kyoto Prize is awarded annually to “those who have contributed significantly to the scientific, cultural, and spiritual betterment of mankind” … Continue reading "Prizes, prizes, prizes"

**Equivariant band matrices and Fourier series**Recall that in the first post of this series we claimed that there exists an infinite matrix \(T\) which is in the closure (in operator norm) of the band matrices with uniformly bounded entries, but for which we have \(\|T^{(R)}\| \to \infty\). Here \[T^{(R)}_{m,n} := \begin{cases} T_{m,n} & \text{ if } |m-n| \le R\\ 0 & … Continue reading "Equivariant band matrices and Fourier series"