#contents
http://www.graphviz.org/Documentation/dotguide.pdf
dot -Tgif -o output.gif input.dot
* 単純な有向グラフ
digraph G
{
// 横方向ならLR
rankdir=TB;
from -> to;
}
* 同列に並べる
digraph G
{
from -> to1;
from -> to2;
to1 -> to2;
{rank = same; to1; to2;}
}
* 矢印を消す
digraph G
{
from -> to [arrowhead = none];
}