#15305: Allow natural morphism between tensor products
-------------------------------------+-------------------------------------
Reporter: tscrim | Owner: sage-combinat
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-5.13
Component: coercion | Resolution:
Keywords: tensor product | Merged in:
coercion | Reviewers: Nicolas Borie, Travis
Authors: Travis Scrimshaw, | Scrimshaw
Nicolas Borie | Work issues:
Report Upstream: N/A | Commit:
Branch: | Stopgaps:
Dependencies: #15309 |
-------------------------------------+-------------------------------------
Changes (by {'newvalue': u'Travis Scrimshaw, Nicolas Borie', 'oldvalue':
u'Travis Scrimshaw'}):
* reviewer: => Nicolas Borie, Travis Scrimshaw
* author: Travis Scrimshaw => Travis Scrimshaw, Nicolas Borie
Old description:
> Given modules `A1, A2, B1, B2` with coercions `A1 -> B1` and `A2 -> B2`,
> there is the natural coercion `A1 # A2 -> B1 # B2` as the tensor of the
> factor coercions. This ticket implements the above coercion as a natural
> coercion for `CombinatorialFreeModule_Tensor`.
New description:
Given modules `A1, A2, B1, B2` with coercions `A1 -> B1` and `A2 -> B2`,
there is the natural coercion `A1 # A2 -> B1 # B2` as the tensor of the
factor coercions. This ticket implements the above coercion as a natural
coercion for `CombinatorialFreeModule_Tensor`.
Apply: [attachment:trac_15305-coercion_tensor_products-ts.patch]
--
Comment:
New version timings
{{{
sage: %timeit S2(S.an_element())
1000 loops, best of 3: 316 us per loop
sage: %timeit S2(S.an_element())
1000 loops, best of 3: 317 us per loop
sage: %timeit S2(S.an_element())
1000 loops, best of 3: 321 us per loop
}}}
Although it returns a `NotImplementedError` when the coercion is not
defined, which is the wrong kind of error, but at least it is an error.
I'll see if I can fix this.
I found this funny:
{{{
sage -t free_module.py
[666 tests, 1.09 s]
}}}
--
Ticket URL: <http://trac.sagemath.org/ticket/15305#comment:14>
Sage <http://www.sagemath.org>
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