TRS: { a__nats() -> a__adx(a__zeros()), a__zeros() -> cons(0(), zeros()), a__incr(cons(X, Y)) -> cons(s(X), incr(Y)), a__adx(cons(X, Y)) -> a__incr(cons(X, adx(Y))), a__hd(cons(X, Y)) -> mark(X), a__tl(cons(X, Y)) -> mark(Y), mark(nats()) -> a__nats(), mark(adx(X)) -> a__adx(mark(X)), mark(zeros()) -> a__zeros(), mark(incr(X)) -> a__incr(mark(X)), mark(hd(X)) -> a__hd(mark(X)), mark(tl(X)) -> a__tl(mark(X)), mark(cons(X1, X2)) -> cons(X1, X2), mark(0()) -> 0(), mark(s(X)) -> s(X), a__nats() -> nats(), a__adx(X) -> adx(X), a__zeros() -> zeros(), a__incr(X) -> incr(X), a__hd(X) -> hd(X), a__tl(X) -> tl(X)} Fail