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

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

assert(!buchiIsEmpty(net));