#10963: More functorial constructions
-------------------------------------+-------------------------------------
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 SimonKing):
Replying to [comment:461 ncohen]:
> It looks like your problem is that the user should "decide" if the
function is a function of `A.B` or a function of `B.A` when what you have
in mind is a function of `{A,B}`. Why don't you have a syntax which takes
as information a set of axioms (and a category if needed), and let some
code decide automatically where it should be put (pick your spanning tree)
?
How could such syntax look like? Of course, we can have a separate class
`ABs`, and then let both `As.B` and `Bs.A` point to it. But even when you
write down the name `ABs`, you already have a choice to do---after all,
why don't you chose `BAs` instead of `ABs`.
> Something like the fancy stuff you like, a metaclass which creates a
class from its SET of axioms, and everything ?
Well, this is my suggestion for the future.
> P.S. : A "spanning tree" in a dag is usually not called a spanning tree
but a spanning out-arborescence. We just don't like "trees" to be directed
`:-P`
Really? I always thought of ''rooted'' trees (and that's what we have
here) as being directed.
--
Ticket URL: <http://trac.sagemath.org/ticket/10963#comment:462>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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