ModularGroup

Finite-index subgroups of (P)SL(2,Integers)

Version 2.0.2
Released 2026-05-04

This project is maintained by Sebastian Engelhardt, Hannah Wagmann, Gabriela Weitze-Schmithüsen

GAP Package ModularGroup

This package provides a collection of algorithms for computing with finite-index subgroups of (P)SL(2,Z).

The current version of this package is version 2.0.2, released on 2026-05-04. For more information, please refer to the package manual. There is also a README file.

License: GPL-3.0-or-later

Dependencies

This package requires GAP version 4.12

The following other GAP packages are needed:

Authors

Sebastian Engelhardt, Luca Leon Junk, Hannah Wagmann, Gabriela Weitze-Schmithüsen.

Citing

Please, cite this package as

[EJWW26] Engelhardt, S., Junk, L. L., Wagmann, H. and Weitze-Schmithüsen, G., ModularGroup, Finite-index subgroups of (P)SL(2,Integers), Version 2.0.2 (2026)
(GAP package), https://ag-weitze-schmithusen.github.io/ModularGroup.

You can get more info by typing Cite("ModularGroup"); in the gap prompt.

Feedback

For bug reports, feature requests and suggestions, please use the issue tracker.