Euler Characteristics of a Family of Congruence Subgroups of $G{L}_m(\mathbb{Z})$

Ivan Horozov

The congruence subgroups $\hat{I}{“}_1(m,p)$ that we consider here are subgroups of $G{L}_m(\mathbb{Z})$ that fix the vector $(0,\dots ,0,1)\mathrm{mod}p$, where $p\ge 5$ is a prime. We present a method a…