#13184: Some Homset are not unique parents
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Reporter: caruso | Owner: nthiery
Type: defect | Status: needs_review
Priority: major | Milestone: sage-5.9
Component: categories | Resolution:
Keywords: homset unique parent | Work issues: sage fails to run
Report Upstream: N/A | Reviewers:
Authors: Xavier Caruso | Merged in:
Dependencies: | Stopgaps:
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Changes (by chapoton):
* status: needs_work => needs_review
Old description:
> I guess it is a bug:
>
> {{{
> sage: k = GF(5)
> sage: H = Hom(k,k)
> sage: H2 = Hom(k,k)
> sage: H is H2
> False
> }}}
>
> I don't know what is the correct way to fix this problem.
>
> More precisely, in sage.categories.homset (l. 223-227), one can read:
>
> {{{
> try:
> # Apparently X._Hom_ is supposed to be cached
> return X._Hom_(Y, category)
> except (AttributeError, TypeError):
> pass
> }}}
>
> However, in this particular case, k._Hom_ is apparently not cached. IMHO,
> caching should be the job of sage.categories.homset.Hom is all cases, but
> I might be wrong.
>
> ----
>
> Apply
>
> 1. [[attachment:trac_13184_sage_5.5.0.beta.patch]]
>
> to the sage library (version >= 5.5.0.beta)
New description:
I guess it is a bug:
{{{
sage: k = GF(5)
sage: H = Hom(k,k)
sage: H2 = Hom(k,k)
sage: H is H2
False
}}}
I don't know what is the correct way to fix this problem.
More precisely, in sage.categories.homset (l. 223-227), one can read:
{{{
try:
# Apparently X._Hom_ is supposed to be cached
return X._Hom_(Y, category)
except (AttributeError, TypeError):
pass
}}}
However, in this particular case, k._Hom_ is apparently not cached. IMHO,
caching should be the job of sage.categories.homset.Hom is all cases, but
I might be wrong.
----
Apply
1. [attachment:trac_13184_sage_5.9.beta.patch]
--
Comment:
here is a rebased and slightly modified patch
for the bot:
apply trac_13184_sage_5.9.beta.patch
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13184#comment:11>
Sage <http://www.sagemath.org>
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