MAYBE MAYBE TRS: { dbl(X) -> n__dbl(X), dbl(0()) -> 0(), dbl(s(X)) -> s(n__s(n__dbl(activate(X)))), s(X) -> n__s(X), activate(X) -> X, activate(n__s(X)) -> s(X), activate(n__dbl(X)) -> dbl(activate(X)), activate(n__dbls(X)) -> dbls(activate(X)), activate(n__sel(X1, X2)) -> sel(activate(X1), activate(X2)), activate(n__indx(X1, X2)) -> indx(activate(X1), X2), activate(n__from(X)) -> from(X), dbls(X) -> n__dbls(X), dbls(nil()) -> nil(), dbls(cons(X, Y)) -> cons(n__dbl(activate(X)), n__dbls(activate(Y))), sel(X1, X2) -> n__sel(X1, X2), sel(0(), cons(X, Y)) -> activate(X), sel(s(X), cons(Y, Z)) -> sel(activate(X), activate(Z)), indx(X1, X2) -> n__indx(X1, X2), indx(nil(), X) -> nil(), indx(cons(X, Y), Z) -> cons(n__sel(activate(X), activate(Z)), n__indx(activate(Y), activate(Z))), from(X) -> cons(activate(X), n__from(n__s(activate(X)))), from(X) -> n__from(X), dbl1(0()) -> 01(), dbl1(s(X)) -> s1(s1(dbl1(activate(X)))), sel1(0(), cons(X, Y)) -> activate(X), sel1(s(X), cons(Y, Z)) -> sel1(activate(X), activate(Z)), quote(0()) -> 01(), quote(dbl(X)) -> dbl1(X), quote(s(X)) -> s1(quote(activate(X))), quote(sel(X, Y)) -> sel1(X, Y) } DUP: We consider a duplicating system. Trs: { dbl(X) -> n__dbl(X), dbl(0()) -> 0(), dbl(s(X)) -> s(n__s(n__dbl(activate(X)))), s(X) -> n__s(X), activate(X) -> X, activate(n__s(X)) -> s(X), activate(n__dbl(X)) -> dbl(activate(X)), activate(n__dbls(X)) -> dbls(activate(X)), activate(n__sel(X1, X2)) -> sel(activate(X1), activate(X2)), activate(n__indx(X1, X2)) -> indx(activate(X1), X2), activate(n__from(X)) -> from(X), dbls(X) -> n__dbls(X), dbls(nil()) -> nil(), dbls(cons(X, Y)) -> cons(n__dbl(activate(X)), n__dbls(activate(Y))), sel(X1, X2) -> n__sel(X1, X2), sel(0(), cons(X, Y)) -> activate(X), sel(s(X), cons(Y, Z)) -> sel(activate(X), activate(Z)), indx(X1, X2) -> n__indx(X1, X2), indx(nil(), X) -> nil(), indx(cons(X, Y), Z) -> cons(n__sel(activate(X), activate(Z)), n__indx(activate(Y), activate(Z))), from(X) -> cons(activate(X), n__from(n__s(activate(X)))), from(X) -> n__from(X), dbl1(0()) -> 01(), dbl1(s(X)) -> s1(s1(dbl1(activate(X)))), sel1(0(), cons(X, Y)) -> activate(X), sel1(s(X), cons(Y, Z)) -> sel1(activate(X), activate(Z)), quote(0()) -> 01(), quote(dbl(X)) -> dbl1(X), quote(s(X)) -> s1(quote(activate(X))), quote(sel(X, Y)) -> sel1(X, Y) } Fail