module main {
  type boolean_t = boolean;
  input x2 : boolean_t;
  var y1, r1, y2, r2 : boolean_t;

  init {
    r1 = false;
    y1 = false;
    r2 = false;
    y2 = false;
  }

  next {
    y1 = r1;
    r1 = !r1;
    y2 = x2 | r2;
    r2 = x2 | r2;
  }

  control {
    check;
    print_results;
  }
}
