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