#10963: More functorial constructions
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Reporter: nthiery | Owner: stumpc5
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-6.1
Component: categories | Resolution:
Keywords: days54 | Merged in:
Authors: Nicolas M. Thiéry | Reviewers: Simon King, Frédéric
Report Upstream: N/A | Chapoton
Branch: | Work issues:
public/ticket/10963 | Commit:
Dependencies: #11224, #8327, | eb7b486c6fecac296052f980788e15e2ad1b59e4
#10193, #12895, #14516, #14722, | Stopgaps:
#13589, #14471, #15069, #15094, |
#11688, #13394, #15150, #15506 |
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Comment (by nthiery):
Replying to [comment:444 pbruin]:
> Second, I think the new method `CartesianProduct.summands()` is inaptly
named. The things of which a product is composed (also in the categorical
sense, in my experience) are normally called ''factors''! Recall that in
a category where both sums and product exist, they are usually not the
same. For example, in the category of sets, the sum is the disjoint
union, and in the category of rings, the sum is the tensor product. It
makes sense that the components of which a product is composed should be
called ''factors'' and the components of which a sum is composed should be
called ''summands''.
Granted, it's not perfect, but it's consistent with the other
preexisting ``summand_`` methods in the context of cartesian products.
I'd be happy to change it, but then we should change all of them at
once for consistency. IMHO This would be best handled in a followup
ticket since this one is already way too big. I am happy adding a
warning about the probable name change in the documentation though.
Also, I would like something different from ``factors'', since we will
also use it in the context of monoids (like for making cartesian
products thereof), and `factors` would be ambiguous. Any suggestions?
Cheers,
Nicolas
--
Ticket URL: <http://trac.sagemath.org/ticket/10963#comment:445>
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