Dear GAP Forum,

Franz G"ahler wrote:

I would like to suggest an other solution here, which might be provided
as a further option. The Hasse diagram would often be greatly simplified
if vertices belonging to the same conjugacy class of subgroups could be
merged. Vertices would then correspond to conjugacy classes of subgroups,

Goetz Pfeiffer has an experimental version to display the table
of marks, but it requires some changes to make it compatible with
version 1.3 of XGAP.

The main task which has to be done is to update and extend "gatlist.g",
which - as you have remarked - is neither in the manual nor yet finished.
I want to make some functions which will allow you to define your
own "type" of lattice and set of functions to manipulate the vertices.
It would then be rather easy to adapt Goetz's TOM lattice.

If this is not feasible in the present version, I hope that at least
in some future version I can type something like

GraphicLattice(g, "ConjugacyClasses");

and, perhaps,

InteractiveLattice(g, "ConjugacyClasses");

At least the table of marks lattice should be ready in one or two month.
I cannot say how long it will take to finish "glatlist.g" and make it
an offical part of XGAP.

best wishes
Frank