Ergodicity versus non-ergodicity for Probabilistic Cellular Automata on rooted trees

TL;DR

This paper investigates the ergodic and non-ergodic behavior of shift-invariant probabilistic cellular automata on rooted d-regular trees, establishing connections with Gibbs measures and characterizing invariant measures.

Contribution

It extends the understanding of stationary measures for PCA on trees and provides conditions for ergodicity and non-ergodicity, including characterization of invariant Bernoulli measures.

Findings

Established a correspondence between stationary measures and space-time Gibbs measures.

Provided sufficient conditions for ergodicity and non-ergodicity on d-ary trees.

Characterized invariant product Bernoulli measures for the PCA.

Abstract

In this article we study a class of shift-invariant and positive rate probabilistic cellular automata (PCA) on rooted d-regular trees $\mathbb{T}^d$. In a first result we extend the results of [10] on trees, namely we prove that to every stationary measure $\nu$ of the PCA we can associate a space-time Gibbs measure $\mu_{\nu}$ on $\mathbb{Z} \times \mathbb{T}^d$. Under certain assumptions on the dynamics the converse is also true. A second result concerns proving sufficient conditions for ergodicity and non-ergodicity of our PCA on d-ary trees for $d\in \{ 1,2,3\}$ and characterizing the invariant product Bernoulli measures.