Opened 7 years ago

Closed 7 years ago

#16011 closed defect (fixed)

Fix _torsion_bound() for elliptic curves over relative number fields

Reported by: pbruin Owned by:
Priority: minor Milestone: sage-6.2
Component: elliptic curves Keywords: relative number field ramification
Cc: cremona, mmasdeu Merged in:
Authors: Marc Masdeu Reviewers: Peter Bruin
Report Upstream: N/A Work issues:
Branch: 94d6219 (Commits) Commit: 94d6219e76683651b78fdcf6c176f15fb87f77a1
Dependencies: Stopgaps:

Description

Computing torsion subgroups of elliptic curves over relative number fields fails:

sage: R.<x> = QQ[]
sage: F.<a> = QuadraticField(5)
sage: K.<b> = F.extension(x^2-3)
sage: E = EllipticCurve(K,[0,0,0,b,1])
sage: E.torsion_subgroup()
...
NotImplementedError: For an ideal in a relative number field you must use relative_ramification_index or absolute_ramification_index as appropriate

The solution should be to make E._torsion_bound() use absolute_ramification_index() instead of ramification_index().

Change History (6)

comment:1 Changed 7 years ago by mmasdeu

  • Branch set to u/mmasdeu/torsion_relative_number_fields
  • Commit set to 0fab9272cba589ec49a58fe77cf7d4524b6e6cbb
  • Status changed from new to needs_review

New commits:

0fab927Fixed torsion_order for relative number fields.

comment:2 Changed 7 years ago by mmasdeu

Done!

comment:3 Changed 7 years ago by pbruin

  • Authors set to Marc Masdeu
  • Reviewers set to Peter Bruin
  • Status changed from needs_review to positive_review

Looks good (and very quick)! One non-essential comment on your patch: the preferred way of referring to Trac tickets is :trac:`16011` instead of #16011.

comment:4 Changed 7 years ago by git

  • Commit changed from 0fab9272cba589ec49a58fe77cf7d4524b6e6cbb to 94d6219e76683651b78fdcf6c176f15fb87f77a1
  • Status changed from positive_review to needs_review

Branch pushed to git repo; I updated commit sha1 and set ticket back to needs_review. New commits:

94d6219Fixed way to refer to ticket.

comment:5 Changed 7 years ago by mmasdeu

  • Status changed from needs_review to positive_review

comment:6 Changed 7 years ago by vbraun

  • Branch changed from u/mmasdeu/torsion_relative_number_fields to 94d6219e76683651b78fdcf6c176f15fb87f77a1
  • Resolution set to fixed
  • Status changed from positive_review to closed
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