Dear Marc, Calling
gap> Stabilizer(auts,Set(AsSet(T),AsSet),OnSetsSets); works for me. OnSetsSets asks for its input to be a sorted list of sorted lists: <https://www.gap-system.org/Manuals/doc/ref/chap41.html#X7C10492081D72376>. Best wishes, Josh ________________________________________ From: Marc Keilberg [keilb...@usc.edu] Sent: 25 November 2019 08:15 To: forum@gap-system.org Subject: [GAP Forum] Error computing a stabilizer in GAP 4.10.2 I was interested in computing the automorphisms of a group sending a given conjugacy class of subgroups to itself, when I encountered an error that I can't make sense of. It only affects one particular subgroup conjugacy class, and none of the others, and I don't know why. N := SmallGroup(81,14); auts := AutomorphismGroup(N); csubs := ConjugacyClassesSubgroups(N);; T := csubs[5]; This is the class of the cyclic subgroup of order 3 generated by N.1*N.2^2. I try to compute the stabilizer as follows: gap> Stabilizer(auts,List(AsList(T),AsList),OnSetsSets); Error, Action not well-defined. See the manual section ``Action on canonical representatives''. at /proc/cygdrive/C/gap-4.10.2-x86_64/lib/oprt.gd:440 called from TestIdentityAction( acts, pnt, act ) at /proc/cygdrive/C/gap-4.10.2-x86_64/lib/oprt.gd:833 called from CallFuncList( StabilizerFunc, arg ) at /proc/cygdrive/C/gap-4.10.2-x86_64/lib/oprt.gi:2874 called from <function "Stabilizer">( <arguments> ) called from read-eval loop at *stdin*:81 you can 'quit;' to quit to outer loop, or you can 'return;' to continue As I indicated, all other conjugacy classes of subgroups seem to work just fine with the same code to compute the stabilizer. So what's happening here? And, as an aside, is there a smarter way to get this sort of stabilizer? Thanks, Marc _______________________________________________ Forum mailing list Forum@gap-system.org https://mail.gap-system.org/mailman/listinfo/forum _______________________________________________ Forum mailing list Forum@gap-system.org https://mail.gap-system.org/mailman/listinfo/forum
