Locally isotropic Steinberg groups II. Schur multipliers

Abstract

We compute Schur multipliers of locally isotropic Steinberg groups and of all root graded Steinberg groups with root systems of rank at least $3$ (excluding the types ${\mathsf{H}}_3$ and ${\mathsf{H}}_4$). As an application, we show that locally isotropic Steinberg groups are well defined as abstract groups.

arXiv commentRewritten section 4.2 and added lemma 23