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

Arunava Mandal, Shashank Vikram Singh

Abstract

Let $G$ be a linear semisimple Lie group without compact factors. We show that uniform approximate lattices $Λ$ arising as regular model sets in $G$ determine the ambient group $G$ in a strong sense. Specifically, for every non-compact Cartan subgroup $C$ of $G$, there exists $g \in G$ such that the intersection $gCg^{-1} \cap Λ^2$ 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 $\mathbb{R}$-rank of the ambient group $G$, drawing on ideas from the work of Prasad and Raghunathan on lattices.

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

Abstract

Let be a linear semisimple Lie group without compact factors. We show that uniform approximate lattices arising as regular model sets in determine the ambient group in a strong sense. Specifically, for every non-compact Cartan subgroup of , there exists such that the intersection 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 -rank of the ambient group , drawing on ideas from the work of Prasad and Raghunathan on lattices.

Paper Structure

This paper contains 14 sections, 21 theorems, 12 equations.

Key Result

Theorem 1.1

Let $G$ be a linear semisimple Lie group without a compact factor and let $\Lambda = P_0(\Gamma, W_0)$ be a regular model set over a cut-and-project scheme $(G,H,\Gamma)$, where $H$ is a linear semisimple Lie group without a compact factor and $\Gamma$ is an irreducible lattice in $G\times H$. Let $

Theorems & Definitions (48)

  • Theorem 1.1: Moore’s Ergodicity-type theorem for hull of a strong approximate lattice
  • Theorem 1.2
  • Theorem 1.3
  • Corollary 1.4
  • Theorem 1.5
  • Remark 1.6
  • Definition 2.1: Approximate subgroup
  • Definition 2.2: Uniform approximate lattice
  • Definition 2.3: Approximate lattice
  • Definition 2.4: Strong approximate lattice
  • ...and 38 more