Elementwise conservative actions and boomerang subgroups

Vortrag von Waltraud Lederle

Sprecher eingeladen von: Prof. Dr. Claire Burrin

Datum: 24.09.25  Zeit: 13.30 - 14.30  Raum: Y27H28

We propose to study actions of countable groups on measure spaces such that every group element individually acts as a conservative transformation, that is, a transformation such that no set of positive measure is disjoint from all its translates. We construct such actions of the free group, using the measurable full group of a hyperfinite equivalence relation. The motivation for our work was to find interesting examples of boomerang subgroups.
Based on joint work with Y. Glasner and T. Hartnick.