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Bounded Generation for $SL_n(Λ)$

Nir Avni, Chen Meiri

TL;DR

This work proves unconditional bounded generation for $SL_d(\Lambda)$ with $d\ge 3$ when $\Lambda$ is an $S$-order in a central division algebra over a number field and $SL_3(\Lambda)$ is generated by elementary matrices. The authors reduce to the case $d=3$, and develop a framework based on $S$-congruence and commgruence completions, ultrafilter ultrapowers, and discrete metaplectic extensions. By translating a potential failure of bounded generation into the existence of a nontrivial metaplectic extension and then ruling out such extensions via metaplectic kernel arguments, they force the desired bounded generation by elementary matrices. The approach blends local–global methods, Bass–Masser–Draxl–Mor-type stability results, and central extension theory to achieve a new isotropic higher-rank bounded generation result with potential implications for width questions in arithmetic groups.

Abstract

Let $Λ$ be an order in a division algebra over a number field. We prove, under some conditions, that $SL_3(Λ)$ is boundedly generated by elementary matrices.

Bounded Generation for $SL_n(Λ)$

TL;DR

This work proves unconditional bounded generation for with when is an -order in a central division algebra over a number field and is generated by elementary matrices. The authors reduce to the case , and develop a framework based on -congruence and commgruence completions, ultrafilter ultrapowers, and discrete metaplectic extensions. By translating a potential failure of bounded generation into the existence of a nontrivial metaplectic extension and then ruling out such extensions via metaplectic kernel arguments, they force the desired bounded generation by elementary matrices. The approach blends local–global methods, Bass–Masser–Draxl–Mor-type stability results, and central extension theory to achieve a new isotropic higher-rank bounded generation result with potential implications for width questions in arithmetic groups.

Abstract

Let be an order in a division algebra over a number field. We prove, under some conditions, that is boundedly generated by elementary matrices.

Paper Structure

This paper contains 13 sections, 20 theorems, 49 equations.

Key Result

Theorem 1.0.1

Let $d\ge 3$, $F$ be a number field, $S$ be a finite set of places of $F$, and $D$ be an $n^2$-dimensional central division algebra over $F$. Let $O$ be the ring of $S$-integers of $F$ and let $\Lambda \subseteq D$ be an $O$-order. Assume that: Then $\mathop{\mathrm{SL}}\nolimits_d(\Lambda)$ is boundedly generated by the elementary matrices.

Theorems & Definitions (50)

  • Theorem 1.0.1
  • Remark 1.0.2
  • Remark 1.0.3
  • Definition 2.1.1
  • Lemma 2.1.2
  • proof
  • Definition 2.2.1
  • Lemma 2.2.2
  • Definition 2.2.3
  • Definition 2.2.4
  • ...and 40 more