MAYBE MAYBE TRS: { activate(X) -> X, activate(n__filter(X1, X2, X3)) -> filter(X1, X2, X3), activate(n__sieve(X)) -> sieve(X), activate(n__nats(X)) -> nats(X), filter(X1, X2, X3) -> n__filter(X1, X2, X3), filter(cons(X, Y), 0(), M) -> cons(0(), n__filter(activate(Y), M, M)), filter(cons(X, Y), s(N), M) -> cons(X, n__filter(activate(Y), N, M)), sieve(X) -> n__sieve(X), sieve(cons(0(), Y)) -> cons(0(), n__sieve(activate(Y))), sieve(cons(s(N), Y)) -> cons(s(N), n__sieve(filter(activate(Y), N, N))), nats(X) -> n__nats(X), nats(N) -> cons(N, n__nats(s(N))), zprimes() -> sieve(nats(s(s(0())))) } DUP: We consider a duplicating system. Trs: { activate(X) -> X, activate(n__filter(X1, X2, X3)) -> filter(X1, X2, X3), activate(n__sieve(X)) -> sieve(X), activate(n__nats(X)) -> nats(X), filter(X1, X2, X3) -> n__filter(X1, X2, X3), filter(cons(X, Y), 0(), M) -> cons(0(), n__filter(activate(Y), M, M)), filter(cons(X, Y), s(N), M) -> cons(X, n__filter(activate(Y), N, M)), sieve(X) -> n__sieve(X), sieve(cons(0(), Y)) -> cons(0(), n__sieve(activate(Y))), sieve(cons(s(N), Y)) -> cons(s(N), n__sieve(filter(activate(Y), N, N))), nats(X) -> n__nats(X), nats(N) -> cons(N, n__nats(s(N))), zprimes() -> sieve(nats(s(s(0())))) } Fail