#12802: test containment of ideals in class MPolynomialIdeal
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Reporter: mariah | Owner: AlexGhitza
Type: enhancement | Status: needs_work
Priority: minor | Milestone: sage-5.1
Component: algebra | Resolution:
Keywords: sd40.5, groebner bases, ideals | Work issues:
documentation
Report Upstream: N/A | Reviewers: Andrey
Novoseltsev
Authors: John Perry | Merged in:
Dependencies: | Stopgaps:
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Comment (by john_perry):
Replying to [comment:10 novoselt]:
> I don't insist on separating whitespace patch now, it is just
inconvenient to dig for changes in 100kb. But please make subsequent
changes in a new little patch.
Okay, new patch coming. It'll be a bit.
> 1. `__cmp__` does not return the result of ``self == other`` contrary
to what is written. I also think that the test should call cmp directly,
since `==` does not always lead to `cmp`.
Got it.
> 2. In `__lt__` the documentation says "We use ideal membership to test
whether the generators of each ideal appears in the other." while only one
of the containment directions should be checked. Despite of the
description of the algorithm in the documentation, the actual code does
something else in the beginning and can return numbers or result of `cmp`
instead of `True/False`.
This was originally code for `__cmp__`, and when I first started working
on it, I had completely forgotten that `__cmp__` doesn't work the same as
these other special functions. That was one reason for the regression I
encountered earlier.
> 3. What will `__cmp__` of ideals return if neither of them is contained
in another? Do we even need it for ideals if there are lt/gt?
When I first worked on this, the `__cmp__` of `Ideal_generic` was trumping
everything else. That's why I redefined `__cmp__`, and it's also why I
originally did some of this in `Ideal_generic`.
> 4. Documentation of `__eq__` is wrong.
It took me a while to find what you meant, but I finally saw it.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12802#comment:11>
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