Ergodicity of the hard-core PCA with a random walk method

TL;DR

This paper presents a simplified and more intuitive proof of the ergodicity of the hard-core probabilistic cellular automaton for neighborhoods of size 2 and 3, using decorrelated islands.

Contribution

It introduces a new proof technique based on decorrelated islands, shortening and unifying previous ergodicity proofs for the hard-core PCA.

Findings

Proves ergodicity for neighborhoods of size 2 and 3

Introduces decorrelated islands as a proof tool

Provides a more intuitive proof approach

Abstract

The hard-core probabilistic cellular automaton has attracted a renewed interest in the last few years, thanks to its connection with the study of a combinatorial game on percolation configurations. We provide an alternative proof for the ergodicity of this PCA for a neighbourhood of size $2$ and $3$, using the notion of decorrelated islands introduced by Casse in 2023, together with some new ideas. This shortens the previous proofs and provides a more intuitive and unified approach.