## 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.

### Call for proposals 2020-2023

The call for proposals for the second funding period 2020-2023 has been released by the DFG.

## Next Activities

## Latest publications

#### Boundary value problems for general first-order elliptic differential operators

Christian Bär, Lashi Bandara

We study boundary value problems for first-order elliptic differential operators on manifolds with compact boundary. The adapted boundary operator...

#### Geometry and topology of the Kerr photon region in the phase space

Carla Cederbaum, Sophia Jahns

We study the set of trapped photons of a subcritical (a<M) Kerr spacetime as a subset of the phase space. First, we present an explicit proof that the...

#### Between buildings and free factor complexes: A Cohen-Macaulay complex for Out(RAAGs)

Benjamin Brück

For every finite graph Γ, we define a simplicial complex associated to the outer automorphism group of the RAAG A_Γ. These complexes are defined as...

#### The Farrell–Jones Conjecture for normally poly-free groups

Benjamin Brück, Dawid Kielak, Xiaolei Wu

We prove the K- and L-theoretic Farrell-Jones Conjecture with coefficients in an additive category for every normally poly-free group, in particular...

## Latest Blog posts

**Girls and boys performing in STEM fields**This is actually already old news (it is from September 2018), but since then it was on my list of things to blog about and only now I found the time to actually do it. There was a meta-study published in Nature Communications (doi:10.1038/s41467-018-06292-0) about the performance of girls and boys in STEM fields. I … Continue reading "Girls and boys performing in STEM fields"

**Compact hyperbolic non-spin manifolds**Recently a preprint was posted on the arXiv ( arXiv:1904.12720 ) claiming to have constructed the first examples of compact orientable hyperbolic non-spin manifolds (in every dimension at least 4). I was a bit surprised by this, since I thought that such examples should be already known. Apparently not … One reason why constructing such … Continue reading "Compact hyperbolic non-spin manifolds"