6 papers
Directional expansion in ergodic actions of countable groups
Michael Björklund, Alexander Fish
We study directional expansion for probability-measure-preserving actions of countable groups through a representation-theoretic group property, the cyclic escape property. An infi…
Trace spectra of simplices in large sets
Michael Björklund, Alexander Fish, Shrey Sanadhya
Given an ordered tuple of vectors in , let be its edge matrix. We prove that, in every fin…
Locally integrable cross sections and their intersection covolume
Nachi Avraham-Re'em, Michael Björklund, Rickard Cullman
We study systematically cross sections of probability preserving actions of unimodular groups and their associated transverse measures, and introduce the invariant \emph{intersecti…
Dynamics of multiplicative groups over fields and Folner-Kloosterman sums
Michael Björklund, Alexander Fish
For two countably infinite fields whose multiplicative groups are isomorphic, we examine invariant couplings between the actions that these groups induce on the additive Pontryagin…
Periodicity of point processes in abelian groups without lattices
Nachi Avraham-Re'em, Michael Björklund, Rickard Cullman
We investigate the intersection covolume of cross sections for probability preserving actions of a class of abelian groups without lattices, including -adic groups and the group…
Ehrhart spectra of large subsets of
Michael Björklund, Rickard Cullman, Alexander Fish
This paper introduces and studies the Ehrhart spectrum of a set , defined as the set of all Ehrhart polynomials of simplices with vertices in , general…