A strong Bishop-Phelps property and a new class of Banach spaces with the property $(A)$ of Lindenstrauss

Abstract

We give a class of bounded closed sets $C$ in a Banach space satisfying a generalized and stronger form of the Bishop-Phelps property studied by Bourgain in \cite{Bj} for dentable sets. A version of the {\it ``Bishop-Phelps-Bollob\'as"} theorem will be also given. The density and the residuality of bounded linear operators attaining their maximum on $C$ (known in the literature) will be replaced, for this class of sets, by being the complement of a $\sigma$-porous set. The result of the paper is applicable for both linear operators and non-linear mappings. When we apply our result to subsets (from this class) whose closed convex hull is the closed unit ball, we obtain a new class of Banach spaces involving property $(A)$ introduced by Lindenstrauss. We also establish that this class of Banach spaces is stable under $\ell_1$-sum when the spaces have a same ``modulus". Applications to norm attaining bounded multilinear mappings and Lipschitz mappings will also be given.