MAYBE
147.11/55.54	MAYBE
147.11/55.54	
147.11/55.54	Problem:
147.11/55.54	 a(a(x1)) -> b(b(x1))
147.11/55.54	 c(c(b(x1))) -> d(c(a(x1)))
147.11/55.54	 a(x1) -> d(c(c(x1)))
147.11/55.54	 c(d(x1)) -> b(c(x1))
147.11/55.54	
147.11/55.54	Proof:
147.11/55.54	 Open
147.11/55.55	EOF