mjo@gentoo.org frp.bissey@gmail.com François Bissey proxy-maint@gentoo.org Proxy Maintainers sci-mathematics@gentoo.org Gentoo Mathematics Project The GAP package 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. gap-packages/congruence