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Fix a bug that could lead to ConjugacyClassesSubgroups to return wrong results when applied to permutation groups #5982

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merged 1 commit into from
Apr 16, 2025

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Fix conjugacy order and use correct partial stabilizers: First Union of orbits of same length, then same Orbits of same length

Also ensure the output is of consistent format:
Representatives are chossen from original list, if normalizer tests have been done other elements are conjugated to the same.

Added assertions to test all conditions.

Fixes #5981

This fix is due to @hulpke I merely cherry-picked it into a PR.

Fix conjugacy order and use correct partial stabilizers:
First Union of orbits of same length, then same Orbits of same length

Also ensure the output is of consistent format:
Representatives are chossen from original list, if normalizer tests have been
done other elements are conjugated to the same.

Added assertions to test all conditions.
@fingolfin fingolfin added kind: bug Issues describing general bugs, and PRs fixing them kind: bug: wrong result Issues describing bugs that result in mathematically or otherwise wrong results, and PRs fixing them labels Apr 13, 2025
@fingolfin fingolfin requested a review from hulpke April 13, 2025 21:21
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Excellent solution and well-documented code :-)

@fingolfin fingolfin merged commit 411e5e9 into master Apr 16, 2025
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@fingolfin fingolfin deleted the mh/ClusterConjugacyPermgroups branch April 16, 2025 10:48
fingolfin added a commit that referenced this pull request Apr 16, 2025
Fix conjugacy order and use correct partial stabilizers:
First Union of orbits of same length, then same Orbits of same length

Also ensure the output is of consistent format:
Representatives are chossen from original list, if normalizer tests have been
done other elements are conjugated to the same.

Added assertions to test all conditions.

Co-authored-by: Alexander Hulpke <hulpke@math.colostate.edu>
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Backported to stable-4.14 in commit acf3154

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Incorrect result given by ConjugacyClassesSubgroups applied to a permutation group
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