Topological rigidity of closures of certain sparse unipotent orbits in finite-volume quotients of $\prod_{i=1}^k\operatorname{SL}_2(\mathbb R)$

Abstract

We give a simple proof about the topological rigidity of closures of certain sparse unipotent orbits in $G/\Gamma$ where $G=\prod_{i=1}^k\operatorname{SL}_2(\mathbb R)$ and $\Gamma$ is an irreducible lattice in $G$.