[GAP Forum] orbits...
Michael.Hartley at nottingham.edu.my
Thu Jul 8 09:13:25 BST 2004
thanks for the advice on the stabilizer bug. I have now upgraded to
On another topic - suppose I want a representative of each orbit of
group acting on a set, without actually finding the whole orbits?
Specifically, I am trying to get Automorphism classes of involutions of
So far, I do this :
AutomorphismClassesInvolutions := function(grp) # should probably be
au := AutomorphismGroup(grp); # find the automorphism group
ss := SylowSubgroup(grp,2); # find a sylow 2-subgroup ss
inv := Filtered(Elements(ss),x -> Order(x) = 2); # get the
involutions in ss
cr := List(Orbits(au,inv),Representative); # get representatives
of the orbits of the involutions under the automorphism group.
Note that the last line before the return will actually compute the
I really just want a representative from each orbit. Or is there a
faster way to get the involutions??
Yours, Mike H...
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