MAYBE
21.62/10.18	MAYBE
21.62/10.18	
21.62/10.18	Problem:
21.62/10.18	 f(y,f(x,y)) -> f(f(a(),y),f(a(),x))
21.62/10.18	
21.62/10.18	Proof:
21.62/10.18	 Open
21.62/10.18	EOF