#19737: SetPartition.to_permutation().cycle_tuples() is not the identity
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Reporter: mantepse | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.11
Component: | Keywords: set partitions, permutations
combinatorics | Authors: Martin Rubey
Merged in: | Report Upstream: N/A
Reviewers: | Branch:
Work issues: | Dependencies:
Commit: |
Stopgaps: |
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The docstring of {{{SetPartition.to_permutation}}} says:
{{{
Convert self to a permutation by considering the partitions ascycles.
}}}
However, I was very surprised to learn that it does not do this by sorting
the blocks. That is, there is currently no guarantee that:
{{{
SetPartition([[1,2,3]]).to_permutation() == Permutation([2,3,1])
}}}
Since this caused some discomfort (I thought a conjecture I like a lot
would be wrong...) I propose to change this behaviour.
--
Ticket URL: <http://trac.sagemath.org/ticket/19737>
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