Improve construction of permutation actions and by this e.g. make FactorCosetAction faster by several magnitudes in certain examples
#5698
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hulpke
added
kind: enhancement
hulpke
changed the title
FactorCosetActionRewrite a condition, mapping with inverse permutations, to test for a small set of numbers rather than a large one. Doing so can give a substantial speedup for constructing certain right transversals. Also adjust of storage limits to reflect hardware progress over 20 years.
using an option, if they are obtained for free during the calculation
Speed up these operations by finding a better subgroup series, defined by actions, and use these actions if possible. Added example and clarify that ordering of points in `FactorCosetAction` is not guaranteed. This resolves gap-system#5040, gap-system#5337
in finding induced permutation representation of FpGroup, even if max parameter was increased in between. This resolves gap-system#5697
In rare cases, class representatives might all lie in existing group, but other elts are outside. Cover this situation. This fixes gap-system#5708
fingolfin
changed the title
FactorCosetAction faster by several magnitudes in certain examples
fingolfin
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May 6, 2024
fingolfin
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topic: performance
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Speed up transversal/action on cosets in permutation group by:
AddCosetInfoStabChainby testing the negative conditionOverall speedup of this (e.g. in Performance problem with creating group actions on cosets #5040) is several magnitudes.
Resolves #5040
Resolves #5337