Forwarded to sage-edu (as requested by John Cremona).
---------- Forwarded message ---------- From: John Cremona <[email protected]> Date: Thu, May 3, 2012 at 5:47 PM Subject: Re: [sage-edu] Abelian Groups: comments and suggestions To: Rob Beezer <[email protected]> Cc: [email protected], David Joyner <[email protected]> Don't forget that we do have things like sage: E = EllipticCurve('11a1') sage: T = E.torsion_subgroup() sage: T.element_class <class 'sage.groups.additive_abelian.additive_abelian_wrapper.EllipticCurveTorsionSubgroup_with_category.element_class'> sage: T Torsion Subgroup isomorphic to Z/5 associated to the Elliptic Curve defined by y^2 + y = x^3 - x^2 - 10*x - 20 over Rational Field sage: O = T(0) sage: type(O) <class 'sage.groups.additive_abelian.additive_abelian_wrapper.EllipticCurveTorsionSubgroup_with_category.element_class'> sage: using the abelian group wrapper for the PID modules code. It's already used in quite a few places. John On 3 May 2012 21:52, Rob Beezer <[email protected]> wrote: > > > On Thursday, March 15, 2012 1:50:08 PM UTC-7, William Stein wrote: >> >> It would be good if somebody rewrote abelian groups from scratch >> taking into account your comments above. Personally, I would probably >> make the user interface be similar to Magma's abelian groups, which is >> pretty well thought out, and will make it easier for people (like me) >> to use both Sage and Magma: > > (Been away for a while and missed this thread.) > > Agreed. I might be the 7th attempt. I started this once, and then when I > came back to it a year later, the category code had changed so much that it > needed a severe rewrite (which I may have lost). But I have support this > summer for exactly this task and a good idea of how to attack it. > > Mike O'S - I'll take your comments into account and would love further > feedback. First attempt is at: > > http://trac.sagemath.org/sage_trac/ticket/9773 > > General strategy: extend a good idea of Cremona and others (iirc) to build > on William's code for finitely generated modules over PID's. A lot of > things (like forming a subgroup, nee submodule) then come for free. > > I wanted to build one abstract class, then extend it into additive and > multiplicative flavors. These would then be suitable for building generic > cyclic groups, the group of units mod n, the multiplicative subgroup of a > finite field, etc, etc. > > Rob -- You received this message because you are subscribed to the Google Groups "sage-edu" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/sage-edu?hl=en.
