> < ^ Date: Thu, 22 May 1997 13:56:41 -0400
> < ^ From: David Joyner <wdj@usna.edu >
> ^ Subject: NormalSubgroups

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

```
```

> < [top]