Full box spaces of free groups

Abstract

In this paper we investigate full box spaces and coarse equivalences between them. We do this in two parts. In part one we compare the full box spaces of free groups on different numbers of generators. In particular the full box space of a free group $F_k$ is not coarsely equivalent to the full box space of a free group $F_d$, if $d\ge 8k+10$. In part two we compare ${\square }_f{\mathbb{Z}}^n$ to the full box spaces of $2$-generated groups. In particular we prove that the full box space of ${\mathbb{Z}}^n$ is not coarsely equivalent to the full box space of any $2$-generated group, if $n\ge 3$.