‐Betti numbers of totally disconnected groups and their approximation by Betti numbers of lattices.

Abstract: The main result is a general approximation theorem for normalised Betti numbers for Farber sequences of lattices in totally disconnected groups. Further, we contribute to the general theory of L 2‐Betti numbers of totally disconnected groups and provide exact computations of the L 2‐Betti numbers of the Neretin group and Chevalley groups over the field of Laurent series over a finite field and their lattices. [ABSTRACT FROM AUTHOR]