#4274: assertion failure in rank for elliptic curves
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Reporter: zimmerma | Owner: was
Type: defect | Status: new
Priority: minor | Milestone: sage-3.2
Component: algebraic geometry | Resolution:
Keywords: |
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Comment (by cremona):
Comment: What's wrong here is the logic in parsing mwrank's output for a
curve (and there are many) where the lower and upper bounds for the rank
as computed by mwrank are not equal. Here the lower bound is 0 and the
upper bound is 2. This is the *correct* mwrank output for a curve whose
rank is 0 and whose Tate-Shafarevich group has 2-rank equal to 2.
The correct behaviour for Sage in this case is: if proof==True, raise a
run-time error (since mwrank by itself is incapable of find the rank for
such a curve); if proof==False, return a rank of 0 silently, showing a
warning if the appropriate misc.verbose flag is set.
I think that this is what the Sage code is trying to do, but it is not
doing it correctly at present.
OK, so that's an informed diagnosis but but not yet a cure!
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/4274#comment:2>
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