218.01/50.71	MAYBE
218.01/50.71	
218.01/50.71	Problem:
218.01/50.71	 a(b(c(x1))) -> c(b(a(x1)))
218.01/50.71	 a(c(x1)) -> a(a(d(a(x1))))
218.01/50.71	 d(a(b(x1))) -> b(a(d(x1)))
218.01/50.71	 d(a(c(x1))) -> b(c(c(x1)))
218.01/50.71	
218.01/50.71	Proof:
218.01/50.71	 Open
218.33/50.71	EOF