digraph abbildung5 {
{
A,B,C,D,E,F,G,H,I [shape=circle]
}
A -> {B,D} [dir=none, penwidth=5];
C -> {A,B,D} [dir=none];
E -> {B,D} [dir=none];
E -> {C,G,H,I} [dir=none, penwidth=5];
F -> {B,H,I} [dir=none, penwidth=5];
H -> {G,I} [dir=none];
}