show · gl2.index all knowls · up · search:

The index of an open subgroup $H$ of $\GL(2,\widehat\Z)$ is the positive integer $[\GL(2,\widehat\Z):H]$.

Similarly, the index of an open subgroup $H$ of $\GL(2,\Z_\ell)$ is the positive integer $[\GL(2,\Z_\ell):H]$.

Authors:
Knowl status:
  • Review status: beta
  • Last edited by Andrew Sutherland on 2021-07-17 11:28:47
Referred to by:
History: (expand/hide all)