Teach FrattiniSubgroup methods to check for solvability #2041
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The generic method and the method using radicals both benefit from checking solvability, and then redispatching (if solvability was not known before, thus preventing an endless loop). The point is that for the former, we are generic anyway, anything may be either trivial to compute or impossible, so we might as well check for solvability, which shouldn't be harder than computing all maximal subgroups (plus, the latter is impossible for huge elementary abelian groups, while the former is trivial). The method using radicals automatically computes whether the group is solvable anyway, so it may just as well use this and redispatch in that case. Resolves gap-system#710
fingolfin
added
the
kind: enhancement
Codecov Report
@@ Coverage Diff @@
## master #2041 +/- ##
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+ Coverage 66.03% 66.03% +<.01%
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Files 898 898
Lines 273398 273406 +8
Branches 12792 12763 -29
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+ Hits 180528 180536 +8
+ Misses 90039 90038 -1
- Partials 2831 2832 +1
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hulpke
approved these changes
Dec 20, 2017
olexandr-konovalov
added
the
release notes: added
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Added to release notes for GAP 4.10 at https://github.com/gap-system/gap/wiki/GAP-4.10-release-notes |
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The generic method and the method using radicals both benefit from
checking solvability, and then redispatching (if solvability was not
known before, thus preventing an endless loop).
The point is that for the former, we are generic anyway, anything may be
either trivial to compute or impossible, so we might as well check for
solvability, which shouldn't be harder than computing all maximal
subgroups (plus, the latter is impossible for huge elementary abelian
groups, while the former is trivial).
The method using radicals automatically computes whether the group is
solvable anyway, so it may just as well use this and redispatch in that
case.
Resolves #710
This PR is currently against the
masterbranch, as I am not sure how it might affect stability. But of course I can easily retarget it, should that seem desirable.