Hello sage-devel, (I sent this from my email a couple of hours ago but it hasn't appeared on the list yet. I am trying again from within Google Groups. Apologies if it ends up being a duplicate post.)
Schemes and their points are not yet properly embedded in the category framework. One of the trac tickets listing the issues is http://trac.sagemath.org/sage_trac/ticket/7946 which mentions that Volker Braun had resolved some of the issues but some related to elements still remain. Here is what seems to be the root of the problem: sage: A = AffineSpace(2, ZZ) sage: p = A(0, 0) sage: p.parent().category().element_class <class 'sage.categories.category.Schemes_abstract.HomCategory. element_class'> sage: type(p) <class 'sage.schemes.generic.morphism.SchemeMorphism_point_affine'> Compare this with sage: type(QQ(0)) <type 'sage.rings.rational.Rational'> sage: QQ(0).parent().category().element_class <class 'sage.categories.quotient_fields.QuotientFields.element_class'> In the latter case (elements of QQ), things are set up so that Sage knows that Rational is a subtype of QuotientFields.element_class. But for schemes, Sage does not know that SchemeMorphism_point_affine is a subtype of Schemes_abstract.HomCategory.element_class. So how do I fix this? I have tried to locate how this is done for QQ, but I haven't succeeded. Can anyone point me to this? -- Best, Alex Alex Ghitza -- http://aghitza.org/ Lecturer in Mathematics -- The University of Melbourne -- Australia -- 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
