MAYBE
0.09/0.18	MAYBE
0.09/0.18	
0.09/0.18	Problem:
0.09/0.18	 dfib(s(s(x)),y) -> dfib(s(x),dfib(x,y))
0.09/0.18	
0.09/0.18	Proof:
0.09/0.18	 Open
0.09/0.18	EOF