show · modcurve.psl2index all knowls · up · search:

The $\PSL_2$-index of a modular curve $X_H$ is the index of $\Gamma_H := \pm H\cap \SL_2(\Z)$ in $\PSL_2(\Z)$; this index is also the degree of the map $j : \Gamma_H \backslash \overline{\mathfrak{h}} \to X(1)$, where $\overline{\mathfrak{h}}$ is the completed upper half-plane.

Knowl status:
  • Review status: beta
  • Last edited by Andrew Sutherland on 2024-03-24 05:56:07
Referred to by:
History: (expand/hide all) Differences (show/hide)