#17364: All homsets category should be subcategories of the category of all
homsets
--------------------------+-------------------------------------
Reporter: nthiery | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.5
Component: categories | Keywords:
Merged in: | Authors: Nicolas M. Thiéry
Reviewers: | Report Upstream: N/A
Work issues: | Branch:
Commit: | Dependencies:
Stopgaps: |
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All homsets category should be subcategories of the category of all
homsets. For example, we want:
{{{
sage: from sage.categories.homsets import Homsets
sage: Schemes().Homsets().is_subcategory(Homsets())
True
sage: AdditiveMagmas().Homsets().is_subcategory(Homsets())
True
sage:
AdditiveMagmas().AdditiveUnital().Homsets().is_subcategory(Homsets())
True
}}}
The inheritance of an homset category ``C.Homsets()`` from
``Homsets()`` used to be implemented in
``HomsetsCategory.extra_super_categories``; this meant that any custom
implementation of ``C.Homsets.extra_super_categories`` would overwrite
it, which broke all the above examples.
This ticket fixes this, and uses the occasion to refactor the logic,
getting rid along the way of the custom ``category_of`` method which
almost duplicated that of functorial constructions. Hopefully the
logic and its the documentation, are clearer now.
--
Ticket URL: <http://trac.sagemath.org/ticket/17364>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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