R = ID
G = True
{ x = 0 }
< x := x + 1 > || < x := x + 2 >
{ x = 3 }



R = x(0, 2) x(1,3)
G = x(0, 1), x(2, 3)
{ x = 0 \/ x = 2 }
x := x + 1
{ x = 1 \/ x = 3 }

R = x(0, 1) x(2,3)
G = x(0, 2), x(1, 3)
{ x = 0 \/ x = 1 }
x := x + 2
{ x = 2 \/ x = 3 }



===========================================


c := false
d := false
((while not c do skip); d := true) || ((while not d do skip); c := true)