// Author: schuessf@informatik.uni-freiburg.de
// Date: 2023-05-10

PetriNet net = (
  alphabet = {a b c d},
  places = {p1 p2 p3 p4 p5 p6},
  transitions = {
    ({p1} a {p2 p3 p4})  
    ({p2 p3 p4} b {p5 p6})  
    ({p5 p6} c {p2 p3})  
    ({p6} d {p4})  
  },
  initialMarking = {p1},
  acceptingPlaces = {p5}
);

assert(buchiIsEmpty(net));