{ Petri net generated by APT for net exercise 1.4 net C } PLACE s1, s2, s3, s4; MARKING s1 : 1, s4 : 1; TRANSITION t1 CONSUME s1 : 1; PRODUCE s3 : 1, s2 : 1; TRANSITION t2 CONSUME s4 : 1, s2 : 1; PRODUCE s1 : 1; TRANSITION t3 CONSUME s2 : 1; PRODUCE s4 : 1; TRANSITION t4 CONSUME s4 : 1, s3 : 1; PRODUCE s1 : 1;