id summary reporter owner description type status priority milestone component resolution keywords cc merged author reviewer upstream work_issues branch commit dependencies stopgaps
14476 non-integral models can cause a bug in local_data for elliptic curves over number fields wuthrich cremona "This example was spotted by Dino Lorenzini:
{{{
sage: t = QQ['t'].0
sage: K. = NumberField(t^4 - t^3-3*t^2 - t +1)
sage: x=-3/5*g^3 + 2/5*g^2 + 3/5*g + 4/5
sage: y=1/15*g^3 - 3/5*g^2 + 3/5*g + 17/15
sage: r = (x^2*y - x*y + y - 1) / (x^2*y - x)
sage: s = (x*y - y + 1) / (x*y)
sage: c = s*(r - 1)
sage: b = c*r
sage: E = EllipticCurve(K,[1-c,-b,-b,0,0])
sage: E.local_data()
}}}
which causes a {{{TypeError}}} in {{{_reduce_local}}}.
Tickets that may be linked to this are #11630 and #9410.
'''Added later:''' Moreover I can add another bug that he showed me
{{{
sage: R. = QQ[]
sage: K. = NumberField(t^4 - t^3 - 3*t^2 - t + 1)
sage: E = EllipticCurve([ -43/625*g^3 + 14/625*g^2 - 4/625*g + 706/625, -4862/78125*g^3 - 4074/78125*g^2 - 711/78125*g + 10304/78125, -4862/78125*g^3 - 4074/78125*g^2 - 711/78125*g + 10304/78125, 0,0])
sage: E.global_integral_model()
}}}
ends in a {{{AssertionError: bug in global_integral_model}}}.
APPLY:
* [attachment:trac_14476_bugs_in_local_data.patch]
* [attachment:trac_14476_trac_links.patch]
'''NOTE:''' 32-bit doctests require #15243 to be applied on top of these patches." defect closed major sage-5.13 elliptic curves fixed local_data sage-5.13.beta0 Chris Wuthrich Frédéric Chapoton, John Cremona N/A merge with #15243