Lower bounds for the spectral radii of adjacency operators on Baumslag-Solitar groups
arXiv:1006.0556
Abstract
We will use free probability techniques to find lower bounds for the spectral radii of the adjacency operators on the Caley graphs of some non-amenable Baumslag-Solitar groups with the standard generators.
The preprint is now withdrawn, because of an error in the technique. (Certain words were counted twice.) However, we are working on producing a correct argument and we are able to obtain a nontrivial lower bound