MAYBE
220.71/56.00	MAYBE
220.71/56.00	
220.71/56.00	Problem:
220.71/56.00	 c(a(a(x1))) -> a(c(x1))
220.71/56.00	 a(c(b(x1))) -> a(d(b(x1)))
220.71/56.00	 a(d(x1)) -> d(a(a(a(x1))))
220.71/56.00	 b(d(x1)) -> b(c(x1))
220.71/56.00	
220.71/56.00	Proof:
220.71/56.00	 Open
220.71/56.00	EOF