Skip to main content
1 of 6
Ville Salo
  • 6.7k
  • 1
  • 17
  • 40

QI-closure of NA$\times$NA

Consider the following closure/containment properties for a class of groups $\mathcal{G}$.

  1. If $G, H$ are f.g. r.p. nonamenable groups, then $G \times H \in \mathcal{G}$.
  2. If $G \in \mathcal{G}$, $G$ is f.p., and $H$ is r.p. and quasi-isometric to $G$, then $H \in \mathcal{G}$.

Here, f.g. means finitely generated, f.p. means finitely presented, r.p. means recursively presented.

What interesting/surprising/non-trivial corollaries do closure properties 1 and 2 have?

The motivation for this question is that I have a class for which I believe I can prove 1 and 2, so I'd like to know what interesting things my class contains just based on that. I already know a very interesting corollary, namely that my class contains a simple group (Burger-Mozes). Unbelievable! Are there other surprises?

Ville Salo
  • 6.7k
  • 1
  • 17
  • 40