Prof. Dr. David Kerr, Mathematisches Institut

This project aims to advance the theory of rigidity and classification for Bernoulli actions of general groups with respect to orbit equivalence and its quantitative strengthenings. One overarching problem is to determine the extent to which the boundary between rigid and flexible behaviour is reflected in geometric or analytic properties of the group, and specifically, whether such properties intervene in questions of entropy invariance under Shannon orbit equivalence.

Our project will explore the regularity properties of non-nuclear C*-algebras, with a particular emphasis on stable rank one and strict comparison. We focus on two main classes of examples: C*-algebras associated with non-amenable groups and crossed product C*-algebras arising from non-amenable actions on compact Hausdorff spaces. We intend to leverage dynamical tools, including dynamical comparison and the structure of topological full groups.