#12254: __cmp__ for torsion subgroups of elliptic curves is too weak.
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Reporter: was | Owner: cremona
Type: defect | Status: new
Priority: minor | Milestone: sage-6.4
Component: elliptic curves | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps: todo
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Comment (by cremona):
I would be very much more disturbed if the output was False (it is True,
by the way). I think this is entirely consistent with the good output:
{{{
sage: AdditiveAbelianGroup([5])
Additive abelian group isomorphic to Z/5
sage: E.torsion_subgroup()
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
}}}
It may be that back in 2012 the torsion subgroup still described itself as
a multiplicative group, which was Bad and got fixed, but I do not remember
when.
If William (who reported this) agrees we can make it another "don't fix".
--
Ticket URL: <http://trac.sagemath.org/ticket/12254#comment:7>
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