#5664: [with patch, needs review] Bugs in PermutationGroup_subgroup.__cmp__
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Reporter: SimonKing | Owner: SimonKing
Type: defect | Status: new
Priority: critical | Milestone: sage-3.4.2
Component: group_theory | Keywords: comparison subgroup
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Comment(by SimonKing):
Replying to [comment:18 wdj]:
> I searched the Gap reference manual and couldn't find it either.
> (Emailed gap support though and will let you know...)
Since, according to the email support, the comparison is by some
lexicographic order of the list of elements, it is perhaps no surprise
that the "<"-relation of Gap does not behave well with respect to
subgroups.
> Maybe we should just use IsSubgroup (I thought < called that method but
I guess not):
As much as I understand the sorting of Gap, we would have
G is proper subgroup of H <=> |G|<|H| and (G<H in Gap's '<'-order)
So, rather than calling IsSubgroup, we might consider to use Order(G); I
guess this is cached and thus faster.
Would this work (and is the cacheing-thing true)?
Cheers,
Simon
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/5664#comment:19>
Sage <http://sagemath.org/>
Sage - Open Source Mathematical Software: Building the Car Instead of
Reinventing the Wheel
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