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peal / vole

A GAP package for backtrack search in permutation groups with graphs
https://peal.github.io/vole
Mozilla Public License 2.0
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Improve `VoleCon.InCoset` for symmetric group cosets #37

Closed wilfwilson closed 2 years ago

wilfwilson commented 2 years ago

Instead of using the default refiner, which involves building a stabiliser chain for a symmetric group, we can refine for the same constraint with a combination of the moved points, a set transporter, and a tuple transporter.

This is now much faster for this special case. Compare the current master branch:

gap> VoleFind.Coset(SymmetricGroup(80) * (1,2,4));; time;
28201

with this PR:

gap> VoleFind.Coset(SymmetricGroup(80) * (1,2,4));; time;
9

Fixes #35.