arXiv subjects

Jacques Audibert

Publications and source records attributed to Jacques Audibert.

5 recordsLinked to original sources

arXiv2025

Zariski-Closures of Linear Reflection Groups

We give necessary and sufficient conditions for a linear reflection group in the sense of Vinberg to be Zariski-dense in the ambient projective general linear group. As an application, we show that every irreducible right-angled Coxeter group of rank $N \geq 3$ virtually embeds Zariski-densely in $\mathrm{SL}_n(\mathbb{Z})$ for all $n \geq N$. This allows us to settle the existence of Zariski-dense surface subgroups of $\mathrm{SL}_n(\mathbb{Z})$ for all $n \geq 3$. Among the other applications are examples of Zariski-dense one-ended finitely generated subgroups of $\mathrm{SL}_n(\mathbb{Z})$ that are not finitely presented for all $n \geq 6$.

math.GT↗

arXiv2023

Rational approximation for Hitchin representations

A consequence of Rapinchuk et al. is that for $S$ a closed surface of genus $g\geq 2$, the set of Hitchin representations of $\pi_1(S)$ with image in $\mathrm{SL}(n,\mathbb{Q})$ is dense in the Hitchin component. We give a dynamical proof of this fact provided that $g\geq 3$. Moreover, we extend it to some other $\mathbb{Q}$-groups such as $\mathrm{Sp}(2k,\mathbb{Q})$ and $\mathrm{G}_2(\mathbb{Q})$, where the results are new.

math.GT↗

arXiv2023

Maximal representations in lattices of the symplectic group

We prove that all lattices of Sp(2n,R), except those commensurable with Sp(4k+2,Z) when n=2k+1, contain the image of infinitely many mapping class group orbits of Zariski-dense maximal representation that are continuous deformations of maximal diagonal representations. In particular, we show that Sp(4k,Z) contain Zariski-dense surface subgroups for all k.

math.GT↗

arXiv2023

Zariski-dense Hitchin representations in uniform lattices

We construct Zariski-dense surface subgroups in infinitely many commensurability classes of uniform lattices of the split real Lie groups $\operatorname{SL}(n,\mathbb{R})$, $\operatorname{Sp}(2n,\mathbb{R})$, $\operatorname{SO}(k+1,k)$, and $\operatorname{G}_2$. These subgroups are images of Hitchin representations. In particular, we show that every uniform lattice of $\operatorname{Sp}(2n,\mathbb{R})$, of $\operatorname{SO}(k+1,k)$ with $k\equiv1,2[4]$ and of $\operatorname{G}_2$ contains infinitely many mapping class group orbits of Zariski-dense Hitchin representations of fixed genus. Together with Long-Thistlethwaite and with a previous paper of the author, it implies that all lattices of $\operatorname{Sp}(4,\mathbb{R})$ contain a Zariski-dense surface subgroup.

math.GT↗

arXiv2022

Zariski-dense surface groups in non-uniform lattices of split real Lie groups

For $\textrm{SL}(n,\mathbb{R})$ ($n\geq3$), $\textrm{SO}(n+1,n)$ ($n\geq2$), $\textrm{Sp}(2n,\mathbb{R})$ ($n\geq2$) and for the adjoint real split form of the exceptional group $\textrm{G}_2$, we exhibit non-uniform lattices in which we construct thin Hitchin representations by arithmetic methods. These representations give infinitely many orbits under the action of the mapping class group (except maybe for $\textrm{G}_2$). In particular, we show that when $p\neq2$ is prime every non-uniform lattice of $\mathrm{SL}(p,\mathbb{R})$ contains thin Hitchin representations.

math.GT↗