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Dear GAP forum:

A simple question: I have a fairly large group (size=10712468422656000)

which I want to understand a little better. (I have a wild guess that G

might be the semidirect product of A16 and C2^10, with C2^10 normal.)

Unfortunately, NormalSubgroups doesn't seem to work on it:

gap> G:=Group(g[1]*g[2]^-1,g[2]*g[3]^-1); Group( ( 2,23,20,17, 8,10)( 3,24,30,28,16, 9)( 4,21,18, 7)( 5,22,19, 6) (11,12,25,26)(13,14,27,15), ( 1, 5,18,29,27,25)( 3, 6,16,28,14,24) ( 4,19,30,23)( 7,15,12,10)( 8,11,13, 9)(20,26,22,21) ) gap> L:=NormalSubgroups(G); Error, Function: <function> must be a function at return Z( p ^ d ) ^ i ... in fun( arg[1][i] ) called from List( [ 0 .. d - 1 ], function ( i ) ... end ) called from GF( p ) called from RationalClassesElementaryAbelianSubgroup( N1, S1 ) called from RationalClassesPElements( G, p, Sum( rationalClasses, Size ) ) called from ... brk> quit;

It works on a smaller group with no problem:

gap> G:=Group((1,2),(2,3)); Group( (1,2), (2,3) ) gap> L:=NormalSubgroups(G); [ Subgroup( Group( (1,2), (2,3) ), [ ] ), Subgroup( Group( (1,2), (2,3) ), [ (1,2,3) ] ), Subgroup( Group( (1,2), (2,3) ), [ (2,3), (1,3) ] ) ]

Any suggestions on how to get around this? - David Joyner

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