The maximal discrete extension of the Hermitian modular group

Aloys Krieg, Martin Raum, Annalena Wernz

Let ${\Gamma }_n({\mathcal{O}}_{\mathbb{K}})$ denote the Hermitian modular group of degree $n$ over an imaginary-quadratic number field $\mathbb{K}$. In this paper we determine i…