POINTS OF STRONG SUBDIFFERENTIABILITY IN DUAL SPACES

摘要

In this paper, motivated by a classical results of Franchetti and Paya [5] on points of strong subdifferentiability, we exhibit several naturally occurring situations when the property of being strongly subdifferentiable can be lifted from a subspace to the entire space. Our methods rely on the deep analysis of strongly proximinal subspaces of finite codimension obtained by Godefroy and Indumathi and techniques from the theory of M-ideals.