ASYMPTOTIC SMOOTHNESS AND UNIVERSALITY IN BANACH SPACES

For 1 < p <= infinity, we study the complexity and the existence of universal spaces for two classes of separable Banach spaces, denoted Ap and Np, and related to asymptotic smoothness in Banach spaces. We show that each of these classes is Borel in the class of separable Banach spaces. Then we build small families of Banach spaces that are both injectively and surjectively universal for these classes. Finally, we prove the optimality of this universality result, by showing in particular that none of these classes admits a universal space.