#18223: new categories for cartesian products with orders
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Reporter: dkrenn | Owner:
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-6.7
Component: categories | Resolution:
Keywords: sd67 | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
public/ticket/18223 | b924b94bc2e1aa12021cc70b3a919532aa1e350a
Dependencies: | Stopgaps:
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Comment (by nthiery):
Salut Vincent!
We had discussed this design with Daniel, and take my share of the blame.
I am not quite happy with this solution. I am not quite happy with other
solutions either. So that's a good occasion for a discussion!
I guess the main question is whether there will be other categories in
the long run where there will be several variants for the cartesian
product, and we want everything to interplay.
If not, then having a specific cartesian product for posets is
probably ok.
If yes, we would want to have some syntax where we can specify options
for the various structures.
{{{
sage: cartesian_product([A,B,C], poset options, xxx options, ...)
}}}
This is more or less what the proposed syntax aims for. But it has the
drawbacks you mention. Possibly this would not be so bad if the
category was parametrized by a "term order":
{{{
sage: cartesian_product([A,B,C],
Posets().CartesianProducts(term_order="lex")
}}}
It would need to be checked whether we can indeed achieve this syntax
(or a similar one) without tweaking too much the functorial
construction infrastructure.
Another related question is whether a single function is sufficient to
specify the order, or not: maybe we would want to provide
implementations of other methods that apply for specific term orders.
Cheers,
Nicolas
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Ticket URL: <http://trac.sagemath.org/ticket/18223#comment:10>
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