Publications

Publications of SPP2026

On this site you find preprints and publications produced within the projects and with the support of the DFG priority programme „Geometry at Infinity“.

39Geometric invariants of discrete and locally compact groups

We develop an algorithm for recognizing whether a character belongs to \(\Sigma^m\). In order to apply it we just need to know that the ambient group is of type \(\mathrm{FP}_m\) or of type \( \mathrm{F}_2\) and that the word problem is solvable for this group. Then finite data is sufficient proof of membership in \(\Sigma^m\), not just for the given character but also for a neighborhood of it.

 

Related project(s):
39Geometric invariants of discrete and locally compact groups

In this paper we develop the theory of homological geometric invariants (following Bieri-Neumann-Strebel-Renz) for locally compact Hausdorff groups. The homotopical version is treated elsewhere. Both versions are connected by a Hurewicz-like theorem.

 

Related project(s):
39Geometric invariants of discrete and locally compact groups

We extend the classical theory of homotopical Σ-sets, defined by Bieri, Neumann, Renz and Strebel for abstract groups, to  locally compact Hausdorff groups. Given such a group G, our geometric invariants are sets of continuous homomorphisms G→R ("characters"). They match the classical Σ-sets if G is discrete, and refine the homotopical compactness properties of Abels and Tiemeyer. Moreover, our theory recovers the definition of low-dimensional geometric invariants for topological gropus proposed by Kochloukova.

 

Related project(s):
39Geometric invariants of discrete and locally compact groups