On Thu, Nov 05, 2009 at 09:47:30AM +1100, Alex Ghitza wrote: > > > Hi Willem Jan, Ronald, > > > I'm putting this on my todo list. About half a year ago I did some > work adding doctests and fixing/reorganising things with scheme > morphisms, but I didn't get a chance to finish. I'll try to have a > look at your patch soon.
I've created ticket #7956 for this. -Willem Jan > On Wed, Nov 04, 2009 at 08:34:52PM +0000, Willem Jan Palenstijn wrote: > > > > Hi all, > > > > Ronald van Luijk encountered the following problem: > > > > sage: S.<p,q> = QQ[] > > sage: A1.<r> = AffineSpace(QQ,1) > > sage: A1_emb = Curve(p-2) > > sage: type(A1_emb) > > <class 'sage.schemes.plane_curves.affine_curve.AffineCurve_generic'> > > sage: g = A1.hom([2,r],A1_emb) > > TypeError: _point_morphism_class() takes exactly 1 non-keyword argument (3 > > given) > > > > We browsed through the schemes module a bit, and the functionality for a > > morphism to an affine curve does seem to exist through functions such as > > AlgebraicScheme_subscheme_affine._point_morphism_class(), but > > is not accessible since AlgebraicScheme_subscheme_affine is not a > > superclass of > > AffineCurve_generic. > > Comparing it to the projective case, AlgebraicScheme_subscheme_projective > > _is_ a superclass of ProjectiveCurve_generic. > > > > Is this a simple oversight in the class hierarchy for AffineCurve_generic, > > or > > is there a more fundamental reason why this does not yet work? > > > > > > I made a patch (for sage 4.2) that makes the class hierarchy for affine > > curves > > similar to that of projective curves, but would appreciate if someone > > familiar > > with the schemes module could take a look since it is a rather invasive > > change: > > > > http://www.math.leidenuniv.nl/~wpalenst/sage/affine_morphism.patch > > > > The patch also changes the constructor of > > SchemeMorphism_on_points_affine_space to expect a number of polynomials > > equal > > to the dimension of the ambient space instead of the dimension of the > > curve/subscheme, analogous to a change to > > SchemeMorphism_on_points_projective_space by David Kohel from 2007. > > > > > > -Willem Jan > > > > P.S. A related issue is that the TypeError above looks incorrect. See ticket > > #7389 for a small patch to correct that. > > > > > > > -- > Alex Ghitza -- Lecturer in Mathematics -- The University of Melbourne > -- Australia -- http://www.ms.unimelb.edu.au/~aghitza/ > > --~--~---------~--~----~------------~-------~--~----~ > 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 > -~----------~----~----~----~------~----~------~--~---
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