MAYBE
0.09/0.17	MAYBE
0.09/0.17	
0.09/0.17	Problem:
0.09/0.17	 r(xs,ys,zs,nil()) -> xs
0.09/0.17	 r(xs,nil(),zs,cons(w,ws)) -> r(xs,xs,cons(succ(zero()),zs),ws)
0.09/0.17	 r(xs,cons(y,ys),nil(),cons(w,ws)) -> r(xs,xs,cons(succ(zero()),nil()),ws)
0.09/0.17	 r(xs,cons(y,ys),cons(z,zs),cons(w,ws)) -> r(ys,cons(y,ys),zs,cons(succ(zero()),cons(w,ws)))
0.09/0.17	
0.09/0.17	Proof:
0.09/0.17	 Open
0.09/0.18	EOF