On the Asymptotic Number of Generators of High Rank Arithmetic Lattices

Abstract

Abert, Gelander and Nikolov [AGN17] conjectured that the number of generators d(Γ) of a lattice Γ in a high rank simple Lie group H grows sub-linearly with v = μ(H/Γ), the co-volume of Γ in H. We prove this for non-uniform lattices in a very strong form, showing that for 2−generic such H’s, d(Γ) = OH(log v/ log log v), which is essentially optimal. While we can not prove a new upper bound for uniform lattices, we will show that for such lattices one can not expect to achieve a better bound than d(Γ) = O(log v).