A nonamenable "factor" of a Euclidean space

TL;DR

The paper constructs an isometry-invariant random partition of Euclidean space into infinite, indistinguishable pieces with a 3-regular tree adjacency, addressing a question by Benjamini and linking geometric partitions with graph properties.

Contribution

It introduces a novel isometry-invariant partition of Euclidean space with a specific adjacency structure and connects indistinguishability to factors of iid, advancing understanding of geometric group actions.

Findings

Partition of Euclidean space into infinite indistinguishable pieces with a 3-regular tree structure.

Representation of finitely generated one-ended amenable Cayley graphs as invariant partitions.

Development of a new technique linking indistinguishability to factors of iid.

Abstract

Answering a question of Benjamini, we present an isometry-invariant random partition of the Euclidean space $\mathbb{R}^d$, $d\geq 3$, into infinite connected indistinguishable pieces, such that the adjacency graph defined on the pieces is the 3-regular infinite tree. Along the way, it is proved that any finitely generated one-ended amenable Cayley graph can be represented in $\mathbb{R}^d$ as an isometry-invariant random partition of $\mathbb{R}^d$ to bounded polyhedra, and also as an isometry-invariant random partition of $\mathbb{R}^d$ to indistinguishable pieces. A new technique is developed to prove indistinguishability for certain constructions, connecting this notion to factor of iid's.