I think this thread should be on sage-nt so I am copying it there. I disagree that E.has_good_reduction(p) should work with the current, possibly non-minimal model. To make the output from your session more consistent would it not be better for E.reduction(p) to be more clever, and first replace E by an integral model minimal at p and then reduce?
John On Wed, Jun 1, 2011 at 1:14 PM, Maarten Derickx <m.derickx.stud...@gmail.com> wrote: > Cause of the slight difference between an elliptic curve and it's > minimal model we have the some inconsistent behavior in sage as shown > at the end of this post. > > I think this behaviour is lightly confusing, and error prone. I think > that in this case E.has_good_reduction(5) should return false because > you are asking about the reduction type of this specific model of the > elliptic curve and not of it's minimal model. The current behaviour is > will alway's be available via E.local_data(5).has_good_reduction(). > Are there any other people with thoughts about this? > > Thanks in advance, > Maarten Derickx > > sage: E=EllipticCurve([5^4,5^6]) > sage: E.has_good_reduction(5) > True > sage: E.reduction(5) > --------------------------------------------------------------------------- > AttributeError Traceback (most recent call > last) > > /Users/maarten/<ipython console> in <module>() > > /Applications/sage-4.6.rc0/local/lib/python2.6/site-packages/sage/ > schemes/elliptic_curves/ell_rational_field.pyc in reduction(self, p) > 3358 disc = self.discriminant() > 3359 if not disc.valuation(p) == 0: > -> 3360 raise AttributeError, "The curve must have good > reduction at p." > 3361 return self.change_ring(rings.GF(p)) > 3362 > > AttributeError: The curve must have good reduction at p. > > -- > To post to this group, send an email to sage-devel@googlegroups.com > To unsubscribe from this group, send an email to > sage-devel+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/sage-devel > URL: http://www.sagemath.org > -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
