#18223: cartesian products with orders
-------------------------------------+-------------------------------------
Reporter: dkrenn | Owner:
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-6.7
Component: categories | Resolution:
Keywords: sd67 | Merged in:
Authors: Daniel Krenn | Reviewers: Benjamin Hackl
Report Upstream: N/A | Work issues:
Branch: u/dkrenn/cat | Commit:
/cartesian-product-posets | 6714aaaf749e2618e44fba307c0e0a389a4e73c1
Dependencies: #18586 | Stopgaps:
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Changes (by vdelecroix):
* status: needs_review => needs_work
Comment:
Instead of using `QQ` which is not a poset in the doctest why not use
available ones from `Posets.<tab>`?
Some more comments
10. In the documentation clqss of `CartesianProductPosets` you should say
that `order` and `order_le` are optionals and what is the default
behavior. You should also document the behavior of
{{{
sage: CartesianProductPoset([X,Y,Z], order='lex', order_le=my_le)
}}}
(or raise an appropriate error)
11. I am not sure how much this is supported but parents are allowed to
have their `category` argument to be set to a tuple as in
{{{
sage: P = Parent(category=(Rings(),Posets()))
sage: P.category()
Join of Category of rings and Category of posets
}}}
In your subclass, the operation `category & Posets()` would break. You
might use the safer `Category.join(my_list_of_categories)`. If you do so,
add an appropriate doctest for that.
12. What is the point of adding `*kwargs` in the `__init__` method of
`CartesianProduct`? If this argument is not supported then it should
simply not exists.
13. Add some `TestSuite(C).run()` for various cartesian products of posets
(i.e. at least with the two default implemented orders and one self
implemented).
14. Since the cartesian product elements are tuples, we might want to use
the orders from the tuple themselves (which is fastest then anything
else). What about an alternative
{{{
def le_native(self, x, y):
return x.value <= y.value
}}}
15. I am not sure that it is good to have the `le_*` methods as being
public. Do you have some feeling about it?
--
Ticket URL: <http://trac.sagemath.org/ticket/18223#comment:32>
Sage <http://www.sagemath.org>
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