The spring layout is "accidentally" finding the normal subgroup
{+/-1}. If we look at a smaller subgraph, the problem should be
apparent.
G= SL(2, ZZ)
S, T= G.gens(); ST= S*T
L= [S^i*ST^j for i in range(4) for j in range(3)]
els= Set([ a*b for a in L for b in L])
gr= G.cayley_graph(generators = [
i think i see what is going on. By reducing the number of vertices
plotted, it appears that the "double edges" are really little clusters
of four edges!
On 13 mar, 21:27, Pierre wrote:
> Dear Tom,
>
> Thanks for your answer! I get the empty set, too. I really wonder what
> is going on with the pi
Dear Tom,
Thanks for your answer! I get the empty set, too. I really wonder what
is going on with the picture though... if one cannot "rely on the
picture", then it pretty much defeats the purpose when it comes to
Cayley graphs, doesn't it?
and i mean, there *is* a double arrow on some edges.
th
