#18277: wrong category for cartesian square of GF(5)
-------------------------------------+-------------------------------------
Reporter: vdelecroix | Owner:
Type: defect | Status: needs_review
Priority: major | Milestone: sage-6.7
Component: categories | Resolution:
Keywords: cartesian_product | Merged in:
Authors: Vincent Delecroix | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/vdelecroix/18277 | c4d96c174a66dd85230054b6aeaf5793f6fdd41c
Dependencies: | Stopgaps:
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Changes (by vdelecroix):
* status: needs_work => needs_review
Old description:
> `GF(5) x GF(5)` does not know that the multiplication is commutative!
> {{{
> sage: GF(5).cartesian_product(GF(5)).category()
> Join of
> Category of rings and
> Category of Cartesian products of distributive magmas and additive
> magmas and
> Category of finite monoids and
> Category of Cartesian products of monoids and
> Category of Cartesian products of commutative additive groups and
> Category of Cartesian products of finite enumerated sets
> sage: GF(5).cartesian_product(GF(5)) in Magmas().Commutative()
> False
> }}}
> It would be reasonable to expect that the category is `Category of
> Cartesian products of rings`.
>
> With the branch applied
> {{{
> sage: GF(5).cartesian_product(GF(5)).category()
> Join of
> Category of Cartesian products of finite commutative rings and
> Category of Cartesian products of finite enumerated sets
> }}}
New description:
`GF(5) x GF(5)` does not know that the multiplication is commutative!
{{{
sage: GF(5).cartesian_product(GF(5)) in Magmas().Commutative()
False
}}}
It would be reasonable to expect that the category is `Category of
Cartesian products of rings`.
With the branch applied
{{{
sage: GF(5).cartesian_product(GF(5)).category()
Join of
Category of finite commutative rings and
Category of Cartesian products of commutative rings and
Category of Cartesian products of finite enumerated sets
}}}
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Ticket URL: <http://trac.sagemath.org/ticket/18277#comment:5>
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