3 papers
math.GR2025
Elementwise conservative actions and new constructions of boomerang subgroups
Yair Glasner, Tobias Hartnick, Waltraud Lederle
We show that countable non-abelian free groups admit uncountably many mutually singular elementwise conservative non-singular random subgroups, which are supported on infinite subg…
math.DS2025
Symbolic substitution systems beyond abelian groups
Siegfried Beckus, Tobias Hartnick, Felix Pogorzelski
In this article we construct the first examples of strongly aperiodic linearly repetitive Delone sets in non-abelian Lie groups by means of symbolic substitutions. In particular, w…
math.DS2025
Siegel-Radon transforms of transverse dynamical systems
Michael Björklund, Tobias Hartnick
We extend Helgason's classical definition of a generalized Radon transform, defined for a pair of homogeneous spaces of an lcsc group , to a broader setting in which one of the…