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arXiv · 2202.04027

Commensurators of normal subgroups of lattices

David Fisher·Mahan Mj·Wouter Van Limbeek
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Abstract

We study a question of Greenberg-Shalom concerning arithmeticity of discrete subgroups of semisimple Lie groups with dense commensurators. We answer this question positively for normal subgroups of lattices. This generalizes a result of the second author and T. Koberda for certain normal subgroups of arithmetic lattices in SO(n,1) and SU(n,1).

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David Fisher, Mahan Mj, Wouter Van Limbeek. 2022-02-08. Commensurators of normal subgroups of lattices. https://arxiv.org/abs/2202.04027

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