A classification of $\mathbb{R}$-Fuchsian subgroups of Picard modular groups

Jouni Parkkonen, Frédéric Paulin

Given an imaginary quadratic extension $K$ of $\mathbb{Q}$, we classify the maximal nonelementary subgroups of the Picard modular group $\mathrm{PU}(1,2;{\mathcal{O}}_K)$ preserv…