MAYBE
139.09/55.36	MAYBE
139.09/55.36	
139.09/55.36	Problem:
139.09/55.36	 a(a(b(b(x1)))) -> b(b(b(a(x1))))
139.09/55.36	 b(a(x1)) -> a(a(a(a(x1))))
139.09/55.36	
139.09/55.36	Proof:
139.09/55.36	 Open
139.09/55.36	EOF