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Dear All,

It looks to me as if this could be a version problem, from the header file

the first version is:

GAP4, Version: 4r2 fix6 of 26-January-2001

The second is version:

GAP4, Version: 4r2 fix3 of 18-May-2000

Perhaps it is an error which has been addded as as a side effect of the

bug fix. I know of simillar problems with other applications.

I have the current version: GAP4, Version: 4r2 fix8 of 7-June-2001

Running on my system, and when I try your problem I get:

gap> g:=SmallGroup(144,32);

<pc group of size 144 with 6 generators>

gap> lat:=LatticeSubgroups(g);

<subgroup lattice of <pc group of size 144 with 6 generators>, 25 classes,

142 subgroups>

Which is the expected answer.

In short try installing the latest bug fixes, to get to this current

version, and you may find your problem is solved. These fixes can be found

at:

http://www-gap.dcs.st-and.ac.uk/~gap/Info4/bugfixes.html

Let me know how you get on.

Karen

On Wed, 15 Aug 2001, Kurt Ewald wrote:

Forum

I have tried the same and it worked:

Loading the library. Please be patient, this may take a while.

GAP4, Version: 4r2 fix3 of 18-May-2000, i586-pc-cygwin-gcc

Components: small, small2, small3, small4, small5, small6, small7,

small8, id2, id3, id4, id5, id6, trans, prim, tbl,

tom installed.

gap> g:=SmallGroup(144,32);

<pc group of size 144 with 6 generators>

gap> lat:=LatticeSubgroups(g);

<subgroup lattice of <pc group of size 144 with 6 generators>, 25 classes,

142 subgroups>

gap>Mit freundlichen Grüßen / best regards

Kurt Ewald

-----Ursprüngliche Nachricht-----

Von: GAP-Forum-Sender@dcs.st-and.ac.uk

[mailto:GAP-Forum-Sender@dcs.st-and.ac.uk]Im Auftrag von Gordon Royle

Gesendet: Mittwoch, 15. August 2001 06:03

An: Multiple recipients of list

Betreff: LatticeSubgroups problemI am trying to determine if a given graph on 72 vertices is a

Cayley graph; its full automorphism group is "SmallGroup(144,32)" and

so I need to know if this has a subgroup of order 72.But if I simply ask for the subgroup lattice, then it crashes

with a mysterious error....---------------------------------------------------------------------ading the library. Please be patient, this may take a while.

GAP4, Version: 4r2 fix6 of 26-January-2001, i686-pc-linux-gnu-gcc

Components: small, small2, small3, small4, small5, small6, small7,

small8, id2, id3, id4, id5, id6, trans, prim, tbl,gap> g := SmallGroup(144,32);

<pc group of size 144 with 6 generators>

gap> l := LatticeSubgroups(g);

Error <obj> is not an element of the parent of <G> at

Error( "<obj> is not an element of the parent of <G>" );

ClosureSubgroup( Pu, i ) called from

ActionSubspacesElementaryAbelianGroup( f, n ) called from

SubgroupsSolvableGroup( G, rec(

retnorm := true ) ) called from

<function>( <arguments> ) called from read-eval-loop

Entering break read-eval-print loop, you can 'quit;' to quit to outer loop,

or you can return to continue

brk>

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