197.89/50.72	MAYBE
197.89/50.72	
197.89/50.72	Problem:
197.89/50.72	 c(a(a(x1))) -> a(c(x1))
197.89/50.72	 a(c(b(x1))) -> a(d(b(x1)))
197.89/50.72	 a(d(x1)) -> d(a(a(a(x1))))
197.89/50.72	 b(d(x1)) -> b(c(x1))
197.89/50.72	
197.89/50.72	Proof:
197.89/50.72	 Open
198.13/50.72	EOF