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. And: thanks for working on this! Best, Alex 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 -~----------~----~----~----~------~----~------~--~---
