#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 | Vincent Delecroix
Branch: u/behackl/cat | Work issues:
/cartesian-product-posets | Commit:
Dependencies: #18586 | 6ca3e5fd32c7fc5398ece1876ce5981f27663a60
| Stopgaps:
-------------------------------------+-------------------------------------
Changes (by vdelecroix):
* status: needs_review => needs_work
Comment:
16. The name `CartesianProductPosets` looks weird. I would rather go for
`CartesianProductPoset` (no `s`) or `PosetsCartesianProduct`. As it is
currently it looks like ''the set of posets that are made from cartesian
products''.
17. You should remove your name from `sage/sets/cartesian_product.py`. I
have nothing agaist authorship but as it is, it looks like spam ;-)
18. There is no example testing that the coercion can get involved in
comparisons. Either it is worth it and it needs a use case or it can be
removed.
19. This is not nice
{{{
+ CartesianProductPosets = LazyImport(
+ 'sage.combinat.posets.cartesian_product',
'CartesianProductPosets')
+ CartesianProduct = CartesianProductPosets
}}}
because
{{{
sage: E = Posets().example()
sage: E.Car<tab>
E.CartesianProduct E.CartesianProductPosets
}}}
which actually point toward the exact same thing. Please change for
{{{
+ CartesianProduct = LazyImport(
+ 'sage.combinat.posets.cartesian_product',
'CartesianProductPosets')
}}}
And some questions:
20. Most methods of finite posets are actually not available in this
class... this is very annoying (but I do not see what can be done at the
level of this ticket).
21. Are you aware that
{{{
sage: C = cartesian_product([ZZ, ZZ], extra_category=Posets())
sage: from sage.combinat.posets.cartesian_product import
CartesianProductPosets
sage: isinstance(C, CartesianProductPosets)
False
}}}
and indeed
{{{
sage: TestSuite(C).run()
Failure in _test_not_implemented_methods:
...
AssertionError: Not implemented method: le
------------------------------------------------------------
The following tests failed: _test_not_implemented_methods
}}}
--
Ticket URL: <http://trac.sagemath.org/ticket/18223#comment:43>
Sage <http://www.sagemath.org>
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