TRS:
 {     g(a()) -> g(b()),
          b() -> f(a(), a()),
  f(a(), a()) -> g(d())}
 POP* + Boolean Semantic Labelling:
  Normal positions:
  pi(f_sl=1) = [1,2], pi(f_sl=0) = [1,2], pi(g_sl=1) = [1]
  
Safe positions:
   pi(g_sl=0) = [1]
  
Precedence:
   f_sl=0 > g_sl=0, 
   f_sl=0 > d_sl=0, 
   g_sl=1 > g_sl=0, 
   g_sl=1 > b_sl=0, 
   b_sl=0 > f_sl=0, 
   b_sl=0 > a_sl=0
   empty
  
Interpretation:
   g^(1):
   0 | 1
   1 | 1
   b^(0):
    | 1
   a^(0):
    | 0
   f^(2):
   00 | 1
   01 | 0
   10 | 0
   11 | 0
   d^(0):
    | 1
   
  
Labelling:
   g^(1):
   0 | 1
   1 | 0
   b^(0):
    | 0
   a^(0):
    | 0
   f^(2):
   00 | 0
   01 | 0
   10 | 0
   11 | 0
   d^(0):
    | 0
   
  
Labelled predicative System:
   {         g_sl=1(a_sl=0();) -> g_sl=0(;b_sl=0()),
                      b_sl=0() -> f_sl=0(a_sl=0(),a_sl=0();),
    f_sl=0(a_sl=0(),a_sl=0();) -> g_sl=0(;d_sl=0())}
  

  Qed