Schur $\sigma$-groups of type $(3,3)$ for $p=3$

Eric Ahlqvist, Richard Pink

For any imaginary quadratic field $K$, the Galois group $G_K$ of its maximal unramified pro-$3$-extension is a Schur $\sigma$-group. If this has Zassenhaus type $(3,3)$, there are 13 po…