English

Determining $\mathbb R$-Rank in Semisimple Lie Groups via uniform approximate Lattice arising as Regular Model Sets

Group Theory 2026-04-03 v1

Abstract

Let GG be a linear semisimple Lie group without compact factors. We show that uniform approximate lattices Λ\Lambda arising as regular model sets in GG determine the ambient group GG in a strong sense. Specifically, for every non-compact Cartan subgroup CC of GG, there exists gGg \in G such that the intersection gCg1Λ2gCg^{-1} \cap \Lambda^2 is non-empty and itself forms a uniform approximate lattice, extending a classical result of Mostow for lattices. The proof relies on a Moore-type ergodicity theorem for the hull of a strong approximate lattice, proved here as a key tool. Moreover, we prove that such approximate lattices determine the R\mathbb{R}-rank of the ambient group GG, drawing on ideas from the work of Prasad and Raghunathan on lattices.

Keywords

Cite

@article{arxiv.2604.01970,
  title  = {Determining $\mathbb R$-Rank in Semisimple Lie Groups via uniform approximate Lattice arising as Regular Model Sets},
  author = {Arunava Mandal and Shashank Vikram Singh},
  journal= {arXiv preprint arXiv:2604.01970},
  year   = {2026}
}

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18 pages