Closed JohnCremona closed 10 years ago
See also #11327 where a more thorough solution was proposed, but not finished, in 2011. The patch (branch) posted there on 2014-08-09 solves both the issue reported there (constructing duals of 2-isogenies over function fields) and this one.
This ticket is therefore redundant and can be closed as a duplicate while #11327 is ready for review.
I confirm that #11327 solves this ticket, too. This should be closed as won't fix.
Reviewer: Chris Wuthrich
In 6.3.beta8:
The problem is that the isogeny construction code uses 2-variable polynomial rings where univariate polynomials would suffice. This can be fixed by using pol.univariate_polynomial() instead of pol in a few places: possibly not the best solution, but it does work. After the changes to be posted:
Note, however, that
EL.isogenies_prime_degree(3)
, while it works correctly and finds two 3-isogenies, does give some warnings:Component: elliptic curves
Keywords: isogeny relative number field
Author: John Cremona
Reviewer: Chris Wuthrich
Issue created by migration from https://trac.sagemath.org/ticket/16779