#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):
Okay, I am wasting my week-end on this bug that had been left to rot for
20 months again, and here is where I am:
In the `__init__` of !FinitePoset you have a hasse diagram on `0,...,n-1`
and a list of labels for the n points. Those are used as the key for the
equality inherited from `UniqueRepresentation`.
Of course, if you apply a graph isomorphism to the list of labels it still
represents the very same poset. But the key is different, so equality
answers 'no'.
Guys this bug is hard to fix because there is a LOT of code that uses
these functions, and there are two layers of pre-treatment (`Poset` and
`FinitePoset.__classcall__`). I would appreciate it if somebody felt
responsible of that and fixed it.
Nathann
P.S.: I created #17059 that fixes some other stupid bug.
--
Ticket URL: <http://trac.sagemath.org/ticket/14019#comment:37>
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