Bernoulli actions of type III$_0$ with prescribed associated flow

Fuente: arXiv
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Main Authors: Berendschot, Tey, Vaes, Stefaan
Format: Preprint
Published: 2021
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author Berendschot, Tey
Vaes, Stefaan
author_facet Berendschot, Tey
Vaes, Stefaan
contents We prove that many, but not all injective factors arise as crossed products by nonsingular Bernoulli actions of the group $\mathbb{Z}$. We obtain this result by proving a completely general result on the ergodicity, type and Krieger's associated flow for Bernoulli shifts with arbitrary base spaces. We prove that the associated flow must satisfy a structural property of infinite divisibility. Conversely, we prove that all almost periodic flows, as well as many other ergodic flows, do arise as associated flow of a weakly mixing Bernoulli action of any infinite amenable group. As a byproduct, we prove that all injective factors with almost periodic flow of weights are infinite tensor products of $2 \times 2$ matrices. Finally, we construct Poisson suspension actions with prescribed associated flow for any locally compact second countable group that does not have property (T).
format Preprint
id arxiv_https___arxiv_org_abs_2106_02471
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle Bernoulli actions of type III$_0$ with prescribed associated flow
Berendschot, Tey
Vaes, Stefaan
Dynamical Systems
Operator Algebras
We prove that many, but not all injective factors arise as crossed products by nonsingular Bernoulli actions of the group $\mathbb{Z}$. We obtain this result by proving a completely general result on the ergodicity, type and Krieger's associated flow for Bernoulli shifts with arbitrary base spaces. We prove that the associated flow must satisfy a structural property of infinite divisibility. Conversely, we prove that all almost periodic flows, as well as many other ergodic flows, do arise as associated flow of a weakly mixing Bernoulli action of any infinite amenable group. As a byproduct, we prove that all injective factors with almost periodic flow of weights are infinite tensor products of $2 \times 2$ matrices. Finally, we construct Poisson suspension actions with prescribed associated flow for any locally compact second countable group that does not have property (T).
title Bernoulli actions of type III$_0$ with prescribed associated flow
topic Dynamical Systems
Operator Algebras
url https://arxiv.org/abs/2106.02471