I 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>

Miles-Receive-Header: reply