On a certain class of Banach spaces

Using a strengthening of the concept of K σ δ set, introduced in this paper, we study a certain subclass of the class of K σ δ Banach spaces; the so-called strongly K σ δ Banach spaces. This class of spaces includes subspaces of strongly weakly compactly generated (SWCG) as well as Polish Banach spaces and it is related to strongly weakly K -analytic (SWKA) Banach spaces as the known classes of K σ δ and weakly K -analytic (WKA) Banach spaces are related.