We consider termination of the STRS with no additional rule schemes: Signature: dom :: N -> N -> N -> N eval :: N -> N -> N fun :: (N -> N) -> N -> N -> N o :: N s :: N -> N Rules: eval(fun(F, X, Y), Z) -> F(dom(X, Y, Z)) dom(s(X), s(Y), s(Z)) -> s(dom(X, Y, Z)) dom(o, s(Y), s(Z)) -> s(dom(o, Y, Z)) dom(X, Y, o) -> X dom(o, o, Z) -> o The system does not satisfy the preconditions to apply static dependency pairs: it is not accessible function passing. No HORPO proof could be found.