#18383: Coercion and comparison for alternating sign matrices
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Reporter: vdelecroix | Owner:
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-6.7
Component: combinatorics | Resolution:
Keywords: | Merged in:
Authors: Vincent Delecroix | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/vdelecroix/18383 | 390e2d7cf57899cde4c7b096ef5b97f0be909574
Dependencies: | Stopgaps:
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Comment (by tscrim):
Replying to [comment:5 vdelecroix]:
> I assumed that there is a total order on `-1,0,1`. Right.
However that doesn't make a good ordering on ASM's.
>The '''only''' things that change with this ticket are:
>
> 1. the embedding `ASM -> MatrixSpace`
Good.
> 2. the fact that coercion takes place in comparisons
This was already done (at least up to comparing the matrices).
> 3. the fact that `cmp(a1,a2)` answers something when `a1` and `a2` are
both `ASM` instead of raising a `NotImplementedError`.
This is an indicator of something which we are doing wrong further up the
chain, in the sense of being both 2&3 compatible, as rich comparisons
should override the behavior of `__cmp__` (see the rich comparisons part
of http://docs.python.org/2/reference/datamodel.html). Again, `cmp` and
related methods are ''gone'' in Python3, so let's not step backwards by
removing the rich comparisons.
> I will not do anything more complicated as I do not know anything about
`ASM`. If you think that the previous implementation was wrong then open a
follow up ticket (and I might possibly close this one as duplicate). If
you think that some of the three points above are wrong then please be
clearer.
I'm not saying its wrong per-say, but it might carry more meaning than it
currently does. I can ask the ASM people what they want, but it's
tangential to my main objection that it is removing Python3 compatibility.
--
Ticket URL: <http://trac.sagemath.org/ticket/18383#comment:6>
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