#11474: Elliptic curves should be unique parent structures
-----------------------------------+--------------------------
Reporter: SimonKing | Owner: cremona
Type: defect | Status: needs_info
Priority: major | Milestone: sage-6.2
Component: elliptic curves | Resolution:
Keywords: unique parent | Merged in:
Authors: Simon King | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Comment (by defeo):
> Not really, but what it is doing at that point of
sage/databases/cremona.py is constructing an elliptic curve from some data
such as the label, which causes it to look that up in the database. What
is the state of your local/share/cremona/cremona_mini.db file? Is it
8537088 bytes? If not, you could try sage -f elliptic_curves.
My cremona_mini.db is up to date. The error doesn't seem related to the
database. In a sage shell
{{{
sage: from sage.schemes.elliptic_curves.ell_rational_field import
EllipticCurve_rational_field
sage: EllipticCurve_rational_field.__new__(EllipticCurve_rational_field)
---------------------------------------------------------------------------
...
AttributeError: 'EllipticCurve_rational_field' object has no attribute
'_EllipticCurve_generic__ainvs'
}}}
With Simon's patch applied (using the `__classcall__` magic all over the
place).
{{{
sage: from sage.schemes.elliptic_curves.ell_rational_field import
EllipticCurve_rational_field
sage: EllipticCurve_rational_field.__new__(EllipticCurve_rational_field)
---------------------------------------------------------------------------
...
TypeError:
sage.misc.fast_methods.WithEqualityById.__new__(EllipticCurve_rational_field)
is not safe, use sage.structure.parent.Parent.__new__()
sage: Parent.__new__(EllipticCurve_rational_field)
---------------------------------------------------------------------------
...
AttributeError: 'EllipticCurve_rational_field' object has no attribute
sage: '_EllipticCurve_generic__ainvs'
}}}
Either way, I don't understand how this line is supposed to work. I think
we need help from Simon, if we want to resurrect his patch.
--
Ticket URL: <http://trac.sagemath.org/ticket/11474#comment:24>
Sage <http://www.sagemath.org>
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