scholarly journals DOMINATION BY POSITIVE WEAK DUNFORD–PETTIS OPERATORS ON BANACH LATTICES

2014 ◽  
Vol 90 (2) ◽  
pp. 311-318 ◽  
Author(s):  
JIN XI CHEN ◽  
ZI LI CHEN ◽  
GUO XING JI

AbstractRecently, H’michane et al. [‘On the class of limited operators’, Acta Math. Sci. (submitted)] introduced the class of weak$^*$ Dunford–Pettis operators on Banach spaces, that is, operators which send weakly compact sets onto limited sets. In this paper, the domination problem for weak$^*$ Dunford–Pettis operators is considered. Let $S, T:E\to F$ be two positive operators between Banach lattices $E$ and $F$ such that $0\leq S\leq T$. We show that if $T$ is a weak$^{*}$ Dunford–Pettis operator and $F$ is $\sigma $-Dedekind complete, then $S$ itself is weak$^*$ Dunford–Pettis.

1977 ◽  
Vol 29 (5) ◽  
pp. 963-970 ◽  
Author(s):  
Mark A. Smith

In a Banach space, the directional modulus of rotundity, δ (ϵ, z), measures the minimum depth at which the midpoints of all chords of the unit ball which are parallel to z and of length at least ϵ are buried beneath the surface. A Banach space is uniformly rotund in every direction (URED) if δ (ϵ, z) is positive for every positive ϵ and every nonzero element z. This concept of directionalized uniform rotundity was introduced by Garkavi [6] to characterize those Banach spaces in which every bounded subset has at most one Čebyšev center.


2002 ◽  
Vol 65 (2) ◽  
pp. 223-230 ◽  
Author(s):  
Marián Fabian ◽  
Vicente Montesinos ◽  
Václav Zizler

Two smoothness characterisations of weakly compact sets in Banach spaces are given. One that involves pointwise lower semicontinuous norms and one that involves projectional resolutions of identity.


2010 ◽  
Vol 201 (2) ◽  
pp. 155-166 ◽  
Author(s):  
Lixin Cheng ◽  
Qingjin Cheng ◽  
Zhenghua Luo

1968 ◽  
Vol 88 (1) ◽  
pp. 35 ◽  
Author(s):  
D. Amir ◽  
J. Lindenstrauss

Author(s):  
KEVIN BEANLAND ◽  
RYAN M. CAUSEY

Abstract For 0 ≤ ξ ≤ ω1, we define the notion of ξ-weakly precompact and ξ-weakly compact sets in Banach spaces and prove that a set is ξ-weakly precompact if and only if its weak closure is ξ-weakly compact. We prove a quantified version of Grothendieck’s compactness principle and the characterisation of Schur spaces obtained in [7] and [9]. For 0 ≤ ξ ≤ ω1, we prove that a Banach space X has the ξ-Schur property if and only if every ξ-weakly compact set is contained in the closed, convex hull of a weakly null (equivalently, norm null) sequence. The ξ = 0 and ξ= ω1 cases of this theorem are the theorems of Grothendieck and [7], [9], respectively.


1993 ◽  
Vol 36 (4) ◽  
pp. 407-413 ◽  
Author(s):  
Jonathan M. Borwein ◽  
Simon Fitzpatrick

AbstractWe show that L1(μ) has a weak Hadamard differential)le renorm (i.e. differentiable away from the origin uniformly on all weakly compact sets) if and only if μ is sigma finite. As a consequence several powerful recent differentiability theorems apply to subspaces of L1.


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