TRS:
 {f(g(x), y, y) -> g(f(x, x, y))}
 POP* + Boolean Semantic Labelling:
  Normal positions:
  pi(f_sl=1) = [1,2,3], pi(f_sl=0) = [1,2,3]
  
Safe positions:
   pi(g_sl=1) = [1], pi(g_sl=0) = [1]
  
Precedence:
   f_sl=1 > f_sl=0, 
   f_sl=1 > g_sl=0
   empty
  
Interpretation:
   g^(1):
   0 | 0
   1 | 0
   f^(3):
   000 | 0
   001 | 0
   010 | 0
   011 | 0
   100 | 0
   101 | 0
   110 | 0
   111 | 0
   
  
Labelling:
   g^(1):
   0 | 0
   1 | 0
   f^(3):
   000 | 1
   001 | 0
   010 | 0
   011 | 1
   100 | 0
   101 | 0
   110 | 0
   111 | 0
   
  
Labelled predicative System:
   {f_sl=1(g_sl=0(;x),y,y;) -> g_sl=0(;f_sl=1(x,x,y;)),
    f_sl=1(g_sl=0(;x),y,y;) -> g_sl=0(;f_sl=0(x,x,y;)),
    f_sl=1(g_sl=0(;x),y,y;) -> g_sl=0(;f_sl=0(x,x,y;)),
    f_sl=1(g_sl=0(;x),y,y;) -> g_sl=0(;f_sl=0(x,x,y;))}
  

  Qed