The maximal discrete extension of $S{L}_2({\mathcal{O}}_K)$ for an imaginary-quadratic number field $K$

Aloys Krieg, Joana Rodriguez, Annalena Wernz

Let ${\mathcal{O}}_K$ be the ring of integers of an imaginary quadratic number field $K$. In this paper we give a new description of the maximal discrete extension of t…