#8451: improve galois representation for elliptic curves
-------------------------------+--------------------------------------------
Reporter: wuthrich | Owner: cremona
Type: defect | Status: needs_review
Priority: major | Milestone: sage-4.4
Component: elliptic curves | Keywords: elliptic curves, galois
representation, is_surjective
Author: Chris Wuthrich | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
-------------------------------+--------------------------------------------
Comment(by wuthrich):
Thanks a lot for looking at it.
> For reducible primes, not sure whether you need is_prime(p) -- doesn't
isogeny_class only list prime degree isogenies?
That may be redudant, but it does not harm.
> Can we get rid of the "irregardless" in is_surjective? I hate that non-
word!
Agree.
> Replace "Borel" with "Borel subgroup" in image_type
Agreed, too.
> I'm not entirely confident enough to give this a positive review on my
own, maybe someone else could look it over too?
Sure, any candidate in mind ?
> Also, a question: if I run over all curves where the code in this ticket
gives one of
>
> The image could not be determined, it is likely that the image in PGL_2
is A_4
>
> The image could not be determined, it is likely that the image in PGL_2
is S_4
>
> or
>
> The image could not be determined, it is likely that the image in PGL_2
is A_5
>
> Are these the only cases that would be incorrect with the code as it is
now?
Yes, I believe so. It is not a frequent error. I was just puzzled why the
original implementation missed this. Had I not rewritten it, I guess no
one would have ever found out.
I hope I have time to add a little patch for the above issues by tomorrow.
Chris.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/8451#comment:6>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--
You received this message because you are subscribed to the Google Groups
"sage-trac" 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-trac?hl=en.
