ℱLp(T) is the algebra of
Fourier transforms of functions in Lp of the circle. It is shown that if F is defined on
the plane and the composition F ∘ ϕ ∈ℱL1 whenever ϕ ∈ℱLp then for all
𝜖 > 0,F(z) = P(z,z) + O(|z|q∕2−𝜖) where P is a polynomial in z and z and
p−1+ q−1= 1(1 < p < 2).