protocon/examplespec/ColorTorus.prot at trunk · ProtocolConvergence/protocon · GitHub

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// Coloring protocol on a torus.
// There are M rows and N columns in the torus.

// Try with:
//   protocon -x ColorTorus.prot -def M 2 -def N 2
// or
//   protocon -x ColorTorus.prot -def M 3 -def N 2
// Do not put the -def flags before the -x flag
// since actions will not be enumerated properly.

constant M := 3;
constant N := 3;

variable x[(M*N)] < 5;

process P[id < (M*N)]
{
  let i := id / N;
  let j := id % N;

  let id_N := ((i+1)%M)*N + j;
  let id_S := ((i-1)%M)*N + j;
  let id_E := i*N + (j+1)%N;
  let id_W := i*N + (j-1)%N;

  symmetric id_adj <- {# id_N, id_S, id_E, id_W #}
  {
    read: x[id_adj];
  }
  write: x[id];

  (future & silent)
    (   x[id]!=x[id_N]
     && x[id]!=x[id_S]
     && x[id]!=x[id_E]
     && x[id]!=x[id_W]
    );

  // Only allow the search to choose actions that can achieve convergence.
  permit:
    ( x[id_N]!=0 && x[id_S]!=0 && x[id_E]!=0 && x[id_W]!=0 && x[id]!=0 --> x[id]:=0; )
    ( x[id_N]!=1 && x[id_S]!=1 && x[id_E]!=1 && x[id_W]!=1 && x[id]!=1 --> x[id]:=1; )
    ( x[id_N]!=2 && x[id_S]!=2 && x[id_E]!=2 && x[id_W]!=2 && x[id]!=2 --> x[id]:=2; )
    ( x[id_N]!=3 && x[id_S]!=3 && x[id_E]!=3 && x[id_W]!=3 && x[id]!=3 --> x[id]:=3; )
    ( x[id_N]!=4 && x[id_S]!=4 && x[id_E]!=4 && x[id_W]!=4 && x[id]!=4 --> x[id]:=4; )
    ;
}