digraph "Fork–join" {
    rankdir=LR;

    { node[style=invis] start end; }
    { node[label="join"] join1 join2; }

    start -> "fork g(1)"        [label="f(1, 2)"];
    "fork g(1)" -> join1        [label="1 × 2"];

    "fork g(1)" -> "fork g(2)"  [label="h(2)"];
    "fork g(2)" -> join2        [label="2 × 2"];

    "fork g(2)" -> join2        [label="2 + 1"];

    join2 -> join1              [label="4 + 3"];

    join1 -> end                [label="2 + 7"];
}