Hilbert irreducibility for integral points on punctured linear algebraic groups

Abstract

Let $K$ be a number field, let $X$ be a smooth integral variety over $K$, and assume that there exists a finite set of finite places $S$ of $K$ such that the $S$-integral points on $X$ are dense. Then the combined conjectures of Campana and Corvaja-Zannier predict that, for every closed subscheme $Z$ of $X$ of codimension at least two, there exists a finite extension $L$ of $K$ and a finite set of finite places $T$ of $L$ such that the $T$-integral points on $(X\setminus Z)_L$ are not strongly thin. The main goal of the present paper is to show that this property holds for all connected linear algebraic groups. Our result builds mainly on recent work on a Hilbert irreducibility type theorem for connected algebraic groups, the purity of strong approximation for semi-simple simply connected quasi-split linear algebraic groups, and the relation between integral strong approximation and the Hilbert property.