MAYBE
0.19/0.20	MAYBE
0.19/0.20	
0.19/0.20	Problem:
0.19/0.20	 active(filter(cons(X,Y),0(),M)) -> mark(cons(0(),filter(Y,M,M)))
0.19/0.20	 active(filter(cons(X,Y),s(N),M)) -> mark(cons(X,filter(Y,N,M)))
0.19/0.20	 active(sieve(cons(0(),Y))) -> mark(cons(0(),sieve(Y)))
0.19/0.20	 active(sieve(cons(s(N),Y))) -> mark(cons(s(N),sieve(filter(Y,N,N))))
0.19/0.20	 active(nats(N)) -> mark(cons(N,nats(s(N))))
0.19/0.20	 active(zprimes()) -> mark(sieve(nats(s(s(0())))))
0.19/0.20	 active(filter(X1,X2,X3)) -> filter(active(X1),X2,X3)
0.19/0.20	 active(filter(X1,X2,X3)) -> filter(X1,active(X2),X3)
0.19/0.20	 active(filter(X1,X2,X3)) -> filter(X1,X2,active(X3))
0.19/0.20	 active(cons(X1,X2)) -> cons(active(X1),X2)
0.19/0.20	 active(s(X)) -> s(active(X))
0.19/0.20	 active(sieve(X)) -> sieve(active(X))
0.19/0.20	 active(nats(X)) -> nats(active(X))
0.19/0.20	 filter(mark(X1),X2,X3) -> mark(filter(X1,X2,X3))
0.19/0.20	 filter(X1,mark(X2),X3) -> mark(filter(X1,X2,X3))
0.19/0.20	 filter(X1,X2,mark(X3)) -> mark(filter(X1,X2,X3))
0.19/0.20	 cons(mark(X1),X2) -> mark(cons(X1,X2))
0.19/0.20	 s(mark(X)) -> mark(s(X))
0.19/0.20	 sieve(mark(X)) -> mark(sieve(X))
0.19/0.20	 nats(mark(X)) -> mark(nats(X))
0.19/0.20	 proper(filter(X1,X2,X3)) -> filter(proper(X1),proper(X2),proper(X3))
0.19/0.20	 proper(cons(X1,X2)) -> cons(proper(X1),proper(X2))
0.19/0.20	 proper(0()) -> ok(0())
0.19/0.20	 proper(s(X)) -> s(proper(X))
0.19/0.20	 proper(sieve(X)) -> sieve(proper(X))
0.19/0.20	 proper(nats(X)) -> nats(proper(X))
0.19/0.20	 proper(zprimes()) -> ok(zprimes())
0.19/0.20	 filter(ok(X1),ok(X2),ok(X3)) -> ok(filter(X1,X2,X3))
0.19/0.20	 cons(ok(X1),ok(X2)) -> ok(cons(X1,X2))
0.19/0.20	 s(ok(X)) -> ok(s(X))
0.19/0.20	 sieve(ok(X)) -> ok(sieve(X))
0.19/0.20	 nats(ok(X)) -> ok(nats(X))
0.19/0.20	 top(mark(X)) -> top(proper(X))
0.19/0.20	 top(ok(X)) -> top(active(X))
0.19/0.20	
0.19/0.20	Proof:
0.19/0.20	 Open
0.19/0.20	EOF