#10667: Morphisms and Objects of Categories
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Reporter: SimonKing | Owner: nthiery
Type: enhancement | Status: needs_info
Priority: major | Milestone:
Component: categories | Keywords: objects morphisms containment
Author: Simon King | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Comment(by nthiery):
Hi Simon!
I have only browsed quickly through this yet. I'll try to have a look
soon at the broken parent you mention in the other comment. Just some
small comments before heading for my bed.
> * In `sage.categories.homset.Hom`, there was an assymmetry between the
categories of the domain and the codomain. I suggest to choose the
''meet'' of both categories. However, note that there was a comment like
this:
> {{{
> To avoid creating superfluous categories, homsets are in the
> homset category of the lowest category which currently says
> something specific about its homsets.
> }}}
> which meant that the endomorphisms of the rational field used to belong
to the "Category of hom sets in Category of rings". I didn't observe any
problems changing it into the "Category of hom sets in Category of
quotient fields".
I wrote this comment. This won't break indeed, but there might
eventually be a penalty in creating that many categories. I need to
think back about it, but this comment might become irrelevant since we
are going to break the inheritance in-between hom categories.
> * `AbstractCategory` (Do I understand correctly that the abstract
category for the category of `ZZ`-modules would be the catogory of
modules? I.e., one abstracts the base ring away?)
As I said, don't bother understanding: that's going to be removed. If
it gets in your way, just kill the beast, and remove right now
everything about AbstractCategory (typically by taking over the
appropriate bits of the patch I mentioned).
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10667#comment:6>
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