Irreducible Koopman representations for nonsingular actions on boundaries of rooted trees

Fuente: arXiv
Saved in:
Bibliographic Details
Main Authors: Danilenko, Alexandre I., Dudko, Artem
Format: Preprint
Published: 2025
Subjects:
Online Access:
Tags: Add Tag
No Tags, Be the first to tag this record!
_version_ 1866917946632175616
author Danilenko, Alexandre I.
Dudko, Artem
author_facet Danilenko, Alexandre I.
Dudko, Artem
contents Let $G$ be a countable branch group of automorphisms of a spherically homogeneous rooted tree. Under some assumption on finitarity of $G$, we construct, for each sequence $ω\in\{0,1\}^\Bbb N$, an irreducible unitary representation $κ_ω$ of $G$. Every two representations $κ_ω$ and $κ_{ω'}$ are weakly equivalent. They are unitarily equivalent if and only if $ω$ and $ω'$ are tail equivalent. Each $κ_ω$ appears as the Koopman representation associated with some ergodic $G$-quasiinvariant measure (of infinite product type) on the boundary of the tree.
format Preprint
id arxiv_https___arxiv_org_abs_2503_03894
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Irreducible Koopman representations for nonsingular actions on boundaries of rooted trees
Danilenko, Alexandre I.
Dudko, Artem
Dynamical Systems
Representation Theory
37A40, 22D10
Let $G$ be a countable branch group of automorphisms of a spherically homogeneous rooted tree. Under some assumption on finitarity of $G$, we construct, for each sequence $ω\in\{0,1\}^\Bbb N$, an irreducible unitary representation $κ_ω$ of $G$. Every two representations $κ_ω$ and $κ_{ω'}$ are weakly equivalent. They are unitarily equivalent if and only if $ω$ and $ω'$ are tail equivalent. Each $κ_ω$ appears as the Koopman representation associated with some ergodic $G$-quasiinvariant measure (of infinite product type) on the boundary of the tree.
title Irreducible Koopman representations for nonsingular actions on boundaries of rooted trees
topic Dynamical Systems
Representation Theory
37A40, 22D10
url https://arxiv.org/abs/2503.03894