TRS: { a__f(0()) -> cons(0(), f(s(0()))), a__f(s(0())) -> a__f(a__p(s(0()))), a__p(s(0())) -> 0(), mark(f(X)) -> a__f(mark(X)), mark(p(X)) -> a__p(mark(X)), mark(0()) -> 0(), mark(cons(X1, X2)) -> cons(mark(X1), X2), mark(s(X)) -> s(mark(X)), a__f(X) -> f(X), a__p(X) -> p(X)} Fail