A Tits alternative for $\mathbb{R}$-buildings of type $\tilde{A}_2$

TL;DR

This paper establishes a Tits alternative and fixed point results for groups acting on $ ilde{A}_2$-buildings, showing that random walks produce strongly regular hyperbolic isometries and that such isometries are semi-simple.

Contribution

It proves a Tits alternative for groups acting on $ ilde{A}_2$-buildings and demonstrates that isometries are semi-simple, extending understanding of group actions on $ ilde{A}_2$-buildings.

Findings

Random walks produce strongly regular hyperbolic isometries with high probability

A Tits alternative is established for groups acting on $ ilde{A}_2$-buildings

Isometries of $ ext{R}$-buildings are semi-simple

Abstract

Let $G$ be a group with a non-elementary action on a (not necessarily discrete) $\tilde{A}_2$-buildings. We prove that, given a random walk on $G$, isometries in $G$ are strongly regular hyperbolic with high probability. As a consequence, we prove a Tits alternative for $G$, as well as a local-to-global fixed point result. We also prove that isometries of (not necessarily complete) $\mathbb{R}$-buildings are semi-simple.