Completing the proof of the Liebeck--Nikolov--Shalev conjecture

Abstract

Liebeck, Nikolov, and Shalev conjectured the existence of an absolute constant $C>0$, such that for every subset $A$ of a finite simple group $G$ with $|A|\ge 2$, there exists $C\log|G|/\log|A|$ conjugates of $A$ whose product is $G$. This paper is a companion to \cite{GLPS}, and together they prove the conjecture. To prove the conjecture, we establish the following skew-product theorem. We show that there exists $ c > 0 $ such that for all $ \epsilon > 0 $ and subsets $ A, B \subseteq G $ of finite simple groups of Lie type, if $ |B| < |G|^{1 - \epsilon} $, then $ |A^{\sigma} B| > |B||A|^{c \epsilon} $ for some $ \sigma \in G $. This result, along with its more involved analogue for alternating groups, constitutes the main contribution of this paper. Our proof leverages deep results from character theory alongside the probabilistic method.