TRS: { a__from(X) -> cons(mark(X), from(s(X))), a__sel(0(), cons(X, Y)) -> mark(X), a__sel(s(X), cons(Y, Z)) -> a__sel(mark(X), mark(Z)), mark(from(X)) -> a__from(mark(X)), mark(sel(X1, X2)) -> a__sel(mark(X1), mark(X2)), mark(cons(X1, X2)) -> cons(mark(X1), X2), mark(s(X)) -> s(mark(X)), mark(0()) -> 0(), a__from(X) -> from(X), a__sel(X1, X2) -> sel(X1, X2)} Fail