Bs. Mordukhovich et Yg. Shao, EXTREMAL CHARACTERIZATIONS OF ASPLUND SPACES, Proceedings of the American Mathematical Society, 124(1), 1996, pp. 197-205
We prove new characterizations of Asplund spaces through certain extre
mal principles in nonsmooth analysis and optimization. The latter prin
ciples provide necessary conditions for extremal points of set systems
in terms of Frechet normals and epsilon-normals.