[GAP Forum] StructureDescription Revisited

[Max Horn]

Am 11.02.2006 um 13:56 schrieb Nilo de Roock:

> Hello GAP forum,
>

[...]

>
> *="... Error, no method found! For debugging hints type ?Recovery from
> NoMethodFound
> Error, no 2nd choice method found for `IsNaturalGL' on 1 arguments  
> called fro\
> m..."
> ( I interpreted the errors as "does not generate a group", or a bug in
> StructureDescription() for which a fix is due...)

To me this seems like a bug...

>
> Size(testG(8,1))= 16
> Size(testG(8,2))= 64
> Size(testG(8,3))= 48
> Size(testG(8,4))= 128
> Size(testG(8,5))= 80
> Size(testG(8,6))= 192
> Size(testG(8,7))= 112
> So there -are- groups generated. But which ones?

You can work around the problem by first converting to e.g. a  
permutation group.

gap> G:=testG(8,2);;
gap> phi:=IsomorphismPermGroup(G);
<action isomorphism>
gap> StructureDescription(Image(phi));
"(C8 x C4) : C2"


Hope that helps!


Max