typedef unsigned(1) token;

place i1 token: 1;
place w1 token;
place c1 token;
place i2 token: 1;
place w2 token;
place c2 token;
place sem token: 1;

trans req1
in { place i1: 1; }
out { place w1: 1; };

trans in1
in { place w1: 1; 
      place sem: 1;}
out { place c1: 1; };

trans out1
in { place c1: 1; }
out { place i1: 1; 
        place sem: 1};

trans req2
in { place i2: 1; }
out { place w2: 1; };

trans in2
in { place w2: 1; 
      place sem: 1;}
out { place c2: 1; };

trans out2
in { place c2: 1; }
out { place i2: 1; 
        place sem: 1};