Maximal Discrete Subgroups of $S{O}^{+}(2,n+2)$

Aloys Krieg, Felix Schaps

We characterize the maximal discrete subgroups of $S{O}^{+}(2,n+2)$, which contain the discriminant kernel of an even lattice, which contains two hyperbolic planes over $\mathbb{Z}$. T…