关于含渐近等距于$l^{beta}(0

智琛  宋眉眉 《数学研究与评论》2010,30(6):1032-1038

两个$l^{p}(Gamma,E)$型空间的单位球面间满等距映射的表现定理及等距延拓

本文得到两个实的$l^{p}(Gamma,E)$型空间单位球面之间满等距映射的表现定理(这里,$1leq p< +infty,pneq 2$, $E$为内积空间),并导出上述映射可延拓为全空间上的实线性等距算子.     

Asymptotically Isometric Copy of lβ (0 ＜β ＜ 1) in Spaces of Bounded Linear Operators

Assume X is a normed space, every x* ∈ S(X*) can reach its norm at some point in B(X), and Y is a β-normed space. If there is a quotient space of Y which is asymptotically isometric to lβ, then L(X, Y) contains an asymptotically isometric copy of lβ. Some sufficient conditions are given under which L(X, Y) fails to have the fixed point property for nonexpansive mappings on closed bounded β-convex subsets of L(X, Y).     

关于含渐近等距于l_1或c_0子空间的Banach空间(英)

Ｐ．Ｎ．Ｄｏｗｌｉｎｇ和Ｃ．Ｊ．Ｌｅｎｎａｒｄ证明了含渐近等距于ｌ_１子空间的Ｂａｎａｃｈ空间不具有不动点性质．本文以对偶形式给出了Ｂａｎａｃｈ空间合渐近等距于ｌ_１或ｃ_０子空间的充分必要条件,并证明了当一个Ｂａｎａｃｈ空间含有渐近等距于ｌ_∞子空间时它必含有渐近等于ｌ_１子空间．     

关于巴拿赫格中的l∞渐进等距拷贝

In this paper, we show that any σ-complete Banach lattice, with a σ-order semicontinuous but not σ-order continuous norm, contains an asymptotically isometric copy of l∞.We also get that the Fenchel-Orlicz space with the Orlicz norm may not contain an asymptotically isometric copy of l∞.     

关于巴拿赫格中的$l^infty$渐进等距拷贝

本文证明了具有$sigma$-序半连续但非$sigma$-序连续范数的$sigma$-完备巴拿赫格包含$l^infty$的渐进等距拷贝.并且证明了具有Orlicz范数的Fenchel-Orlicz空间不一定含有$l^infty$的渐进等距拷贝.     

β-范空间中l_β(β<1)的渐进等距Copy问题的研究

我们给出了赋β-范空间X包含lβ(β<1)的一个渐进等距copy的定义,并且得到:若一个β-范空间X包含lβ(β<1)的一个渐进等距copy,则在X的闭有界β-凸子集上的非扩张映射没有不动点.还得到了一个β-范空间包含lβ(β<1)的渐进等距copy的某些充分必要条件.注意:本章所有的β满足β<1.     

On Asymptotically Isometric Copies of lβ (0 《β《1)

We get the characterizations of the family of all nonnegative,subadditive,β-absolutely homogeneous and continuous functionals defined on X,when the β-normed space X contains an asymptotically isometric copy of lβ.Moreover,it is proved that if a closed bounded β-convex subset K of a β-normed space contains an asymptotically isometric lβ-basis,then K contains a closed β-convex subset C which fails the fixed point property.     

Every nonreflexive subspace of fails the fixed point property

The main result of this paper is that every nonreflexive subspace of fails the fixed point property for closed, bounded, convex subsets of and nonexpansive (or contractive) mappings on . Combined with a theorem of Maurey we get that for subspaces of , is reflexive if and only if has the fixed point property. For general Banach spaces the question as to whether reflexivity implies the fixed point property and the converse question are both still open.

     

Cesàro function spaces fail the fixed point property

The Cesàro sequence spaces , are reflexive but they have the fixed point property. In this paper we prove that in contrast to these sequence spaces the corresponding Cesàro function spaces on both and for are not reflexive and they fail to have the fixed point property.