Opened 11 years ago

Last modified 11 years ago

#11601 closed enhancement

Generic congruence subgroups — at Version 2

Reported by: David Loeffler Owned by: Craig Citro
Priority: major Milestone: sage-5.0
Component: modular forms Keywords: modular subgroup congruence sd35
Cc: Merged in:
Authors: David Loeffler Reviewers:
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: #10335, #11422, #11598, #5048, #10453 Stopgaps:

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Description (last modified by David Loeffler)

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 - #5048 - #10453 - this one - #10546.

Change History (4)

Changed 11 years ago by David Loeffler

Attachment: trac_11601-congroups.patch added

Patch against 4.7.1.alpha4 + dependencies as in ticket description

comment:1 Changed 11 years ago by David Loeffler

Status: newneeds_review

comment:2 Changed 11 years ago by David Loeffler

Description: modified (diff)

Changed 11 years ago by David Loeffler

New version rebased for 4.7.2.alpha3

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