@startdot digraph associative { rankdir = RL; node [fontsize = 11 ]; s1 [label="A"]; s2 [label="B"]; s3 [label="C"]; s4 [label="D"]; s1 -> s2 [label="f"] s2 -> s3 [label="g"] s3 -> s4 [label="h"] s1 -> s3 [label="g∘f"] s2 -> s4 [label="h∘g"] } @enddot