digraph G { style=bold; subgraph cluster_outer { Act_1 -> Act_21; Act_1 -> Act_23; Act_25 -> Act_3; subgraph cluster_inner { label = " Act_2"; {Act_21 -> Act_22 [minlen=2]; rank=same;} Act_22 -> Act_23; Act_22 -> Act_24; {Act_23 -> Act_24 [minlen=2]; rank=same;} Act_23 -> Act_25; Act_24 -> Act_25; } } Ext_1 -> Act_1; Act_3 -> Ext_2; Ext_3 -> Act_24; }