Iryna Banakh, Taras Banakh, Elena Riss
On $r$-reflexive Banach spaces

Comment.Math.Univ.Carolin. 50,1 (2009) 61-74.

Abstract:A Banach space $X$ is called {$r$-reflexive} if for any cover $\Cal U$ of $X$ by weakly open sets there is a finite subfamily $\Cal V\subset \Cal U$ covering some ball of radius 1 centered at a point $x$ with $\|x\|\leq r$. We prove that an infinite-dimensional separable Banach space $X$ is $\infty $-reflexive ($r$-reflexive for some $r\in \Bbb N$) if and only if each $\varepsilon $-net for $X$ has an accumulation point (resp., contains a non-trivial convergent sequence) in the weak topology of $X$. We show that the quasireflexive James space $J$ is $r$-reflexive for no $r\in \Bbb N$. We do not know if each $\infty $-reflexive Banach space is reflexive, but we prove that each separable $\infty $-reflexive Banach space $X$ has Asplund dual. As a by-product of the proof we obtain a covering characterization of the Asplund property of Banach spaces.

Keywords: reflexive Banach space, $r$-reflexive Banach space, Asplund Banach space
AMS Subject Classification: 46A25, 46B10, 46B22