Generalized second-order derivatives of convex functions in reflexive Banach spaces
Chi Ngoc Do · Transactions of the American Mathematical Society · 1992
Generalized second-order derivatives introduced by Rockafellar in finite-dimensional spaces are extended to convex functions in reflexive Banach spaces. Parallel results are shown in the infinite-dimensional case. A result that plays an important role in applications is that the generalized second-order differentiability is preserved under the integral sign.