digraph {
    subgraph cluster_0 {
      label="device 0";
      T_1 [label="T_1(A^W)"];
      T_2 [label="T_2(A^R, B^W)"];
    }
    subgraph cluster_1 {
      label="device 1";
      T_3 [label="T_3(A^R, C^W)"];
      T_4 [label="T_4(B^R, C^R, D^W)"];
    }
    T_1 -> T_2 [label="A"];
    T_1 -> T_3 [label="A"];
    T_2 -> T_4 [label="B"];
    T_3 -> T_4 [label ="C"];
}