id summary reporter owner description type status priority milestone component resolution keywords cc merged author reviewer upstream work_issues branch commit dependencies stopgaps
11601 Generic congruence subgroups David Loeffler Craig Citro "This ticket adds functionality to work with arbitrary congruence subgroups of the modular group (specified by a level N and a subgroup of the finite group {{{ SL(2, Z / N Z) }}}). These support all the basic functionality one would expect: computation of index, genus, elliptic points, cusps, etc. There is also a facility to compute the congruence closure of a (possibly noncongruence) subgroup.
Some ""rationalisation"" is also included: e.g. one can no longer create {{{Gamma1(1)}}} or {{{GammaH(11, [2])}}}, which previously existed as less-functional duplicates of {{{SL2Z}}} and {{{Gamma0(11)}}}. (They previously played a role in ""remembering"" where certain degeneracy maps would go, but they didn't do this very well -- which was the cause of the issue at #10453 -- and the new more robust approach introduced at #10453 means we can get rid of them at last.)
Part of a series of tickets: #10335 - #11422 - #11598 - #10453 - #5048 - this one - #10546.
Apply [attachment:11601.4.patch] on top of #5048. Once this is merged, #12001 can be closed as fixed." enhancement closed major sage-5.0 modular forms fixed modular subgroup congruence sd35 sage-5.0.beta1 David Loeffler Johan Bosman N/A #10335, #11422, #11598, #10453, #5048