# gap-pkg-congruence

[The Congruence package](https://gap-packages.github.io/congruence/) provides
functions to construct several types of canonical congruence subgroups in
`SL_2(Z)`, and also intersections of a finite number of such subgroups.
Furthermore, it implements the algorithm for generating Farey symbols for
congruence subgroups and using them to produce a system of independent
generators for these subgroups.