MODULE main
VAR
	wantp : boolean;
	wantq : boolean;
  procp : process user(wantp, wantq);
  procq : process user(wantq, wantp);
ASSIGN
	init(wantp) := FALSE;
	init(wantq) := FALSE;
--SPEC
  --AG (proc1.state = entering -> AF proc1.state = critical)

MODULE user(wantp, wantq)
VAR
  state : {p1,p2,p3,p4,p5};
ASSIGN
  init(state) := p1;
  next(state) := 
    case 
      state = p1 : {p1,p2};
      state = p2 & wantq = FALSE : p3;
      state = p3 : p4;
      state = p4 : p5;
			state = p5 : p1;
      TRUE : state;
    esac;
  next(wantp) := 
    case
      next(state) = p4 : TRUE;
			next(state) = p1 & state = p5 : FALSE;
      TRUE : wantp;
    esac;
FAIRNESS
  running