> < ^ Date: Wed, 19 Jan 2000 12:46:22 GMT
> < ^ From: Leonard Soicher <l.h.soicher@qmul.ac.uk >
> ^ Subject: LatticeByCyclicExtension

Dear Forum,

Using GAP 4.1, I have found LatticeByCyclicExtension very useful to
construct certain small subgroups of a given group (to test as
possible groups of automorphisms of experimental designs with
certain properties). My problem is that even though the groups I
require are all soluble, I get the following sort of error:

gap> LatticeByCyclicExtension(SymmetricGroup(10),IsSolvable);
Error the perfect residuum is too large at
Error( "the perfect residuum is too large" );
RepresentativesPerfectSubgroups( G ) 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

One small additional point: it appears that the trivial subgroup is
always included in the lattice computed by LatticeByCyclicExtension(G,f),
whether it satisfies the function f or not (is this correct?).
If so, this "feature" should be documented.

Regards, Leonard.

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