Proof of Theorem 4. We proceed by induction on n, the number of building block functions. For the purpose of this proof only, we denote the function V : (S 1 ) n → R whose domain is the n-dimensional torus by V n ; we note that the formula for V n certainly depends not only on the dimension n but also on the building blocks associated with the rotational axes. Nevertheless, the structure of this proof is independent of which building blocks appear.