MAYBE
41.88/11.18	MAYBE
41.88/11.18	
41.88/11.18	Problem:
41.88/11.18	 a(b(x1)) -> x1
41.88/11.18	 a(c(x1)) -> c(c(b(b(x1))))
41.88/11.18	 b(c(x1)) -> a(a(x1))
41.88/11.18	
41.88/11.18	Proof:
41.88/11.18	 Open
41.88/11.18	EOF