Bounded generation of Steinberg groups over Dedekind rings of arithmetic type

Abstract

The main result of the present paper is bounded elementary generation of the Steinberg groups $\mathrm{St}(\Phi ,R)$ for simply laced root systems $\Phi$ of rank $\ge 2$ and arbitrary Dedekind rings of arithmetic type. Also, we prove bounded generation of $\mathrm{St}(\Phi ,{\mathbb{F}}_q[t,t^{-1}])$ for all root systems $\Phi$, and bounded generation of $\mathrm{St}(\Phi ,{\mathbb{F}}_q[t])$ for all root systems $\Phi \ne {\mathsf{A}}_1$. The proofs are based on a theorem on bounded elementary generation for the corresponding Chevalley groups, where we provide uniform bounds.