#14019: equality is broken for Posets
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Reporter: ncohen | Owner: sage-combinat
Type: defect | Status: needs_info
Priority: major | Milestone: sage-6.4
Component: combinatorics | Resolution:
Keywords: | Merged in:
Authors: Nathann Cohen | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/andrew.mathas/ticket/14019 | d10a6efa75561632cdc76b2c98c5eca4312372ec
Dependencies: | Stopgaps: #14185
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Comment (by ncohen):
Yo !
> `relabel()` does return a new poset.
Oh, True, True, I had forgotten what exactly the problem was. Two years
ago, after all `:-D`
Cool, then the interface will not even change.
> The simplist change would be to make the Hasse diagram the only part of
the construction info, however this would mean we'd have to relabel the
Hasse diagram at construction time rather than when calling
`hasse_diagram()`.
Indeed.I will do just that.
> This also has the drawback of not being able to use the same digraph for
all relabelings of a poset, which is probably used by the linear
extensions and creates a much larger memory usage (and data duplication).
>
> Hopefully before you have gotten angry, I think better standardization
could be used here too.
I was angry two years ago, because I was told that the problem would be
fixed, and it was not. Jori had been doing a lot of work to fix/improve
the poset class in the last two days, and I just don't want to tell him
that this bug will stay because nobody is willing to make a move.
I will write the branch that rewrites .relabel properly, and that will be
all.
Nathann
--
Ticket URL: <http://trac.sagemath.org/ticket/14019#comment:34>
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