notes/school/di-ma/uebung/08/08_2_1.dot

digraph {
    node [ shape="circle" ];
    {
        rank=same;
        1;
        2;
    }

    {
        rank=same;
        3;4;
    }
    1 -> 3 -> 4 -> 2 -> 1;
    2 -> 3;
    1 -> 4;
}