##### Department of Mathematics,

University of California San Diego

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### Seminar in Operator Algebras

## Ben Hayes

#### Vanderbilt University

## Weak equivalence to Bernoulli shifts for some algebraic actions

##### Abstract:

Given two actions of a countable, discrete group $G$ on probabilty space $X,Y$ there is a notion of when the action on $X$ is weakly contained in the action on $Y$ (analogous to weak containment of representations) due to Kechris: it roughly says that any finitary piece of the action of $G$ on $X$ can be approximated by some finitary piece of $G$ on $Y$ (equivalent the measure on $X$ is a weak* limit of the factors of the measure on $Y$). We then say that two actions are weakly equivalent when each is weakly contained in the other. We study when algebraic actions of $G$ (i.e. an action by automorphisms on a compact, metrizable, abelian group) are weakly equivalent to Bernoulli shifts and find a natural class of actions related to invertible convolution operators on $G$. As part of our work, we also give conditions under which such actions are free.

Host: Adrian Ioana

### September 16, 2016

### 11:00 AM

### AP&M 5218

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