模糊星形数空间在L_p度量下的紧集刻画

1990年,P.Diamond首次给出了由全体相对于原点的模糊星形数构成的空间在Lp度量下的紧集刻画。后来,Congxin Wu和Zhitao Zhao通过一个反例指出了P.Diamond的刻画是不正确的,并给出了一种正确的刻画。在这篇文章中,我们将进一步推广这个结论,得到了全体模糊星形数空间在Lp度量下的紧集刻画。     

空间（Lμ^p）^m的弱Banach-Saks性质

证明了由m个Lμp空间产生的Banach向量空间（Lμp）m的弱Banach-Saks性质,其中m是自然数, 1 p 〈＋∞.当m= 1时,这就是著名的Banach-Saks-Szlenk定理.运用该性质,还给出了定义在向量空间Rm的一个凸集上的非负连续凸函数与取值在空间（Lpμ）m的一个弱紧子集中的向量值函数的复合函数的积分不等式.当这些向量值函数属于由m个Lμ∞空间产生的积空间（Lμ∞）m的一个弱＊紧子集时,类似的积分不等式还是成立的.     

板几何中具完全反射边界条件的迁移方程

在Lp（1≤p〈∞）空间上研究了板几何中具完全反射边界条件下各向异性、连续能量、非均匀介质的迁移方程.证明了其迁移算子产生C0群和该群的Dyson-Phillips展开式的二阶余项在Lp（1≤p〈∞空间上是紧的及在L^1空间上是弱紧的,从而得到了该迁移算子的谱在区域Г中仅由有限个具有限代数重数的离散本征值组成和占优本征值的存在性等结果．     

板几何中具反射边界条件的迁移算子的谱分析

在Lp(1 p<∞)空间上研究了板几何中具反射边界条件下各向异性、连续能量、非均匀介质的迁移方程,证明了该迁移算子产生C0半群的Dyson-Phillips展开式的二阶余项在Lp(1相似文献   

L-拓扑空间中的几乎超紧L-子集

在L-拓扑空间中定义了L-子集的几乎超紧性,讨论了几乎超紧L-子集的性质以及L-子集的几乎超紧性与超紧性、近似超紧性及几乎良紧性之间的关系,给出了几乎超紧L-子集的网式及滤子刻画并证明了L-拓扑空间的几乎超紧性是几乎紧性的“L-推广”.     

Rotenberg模型中迁移半群的本质谱

在Lp（1（≤）p＜＋∞）空间中,本文运用半群理论研究了Rotenberg模型中具光滑边界条件的迁移半群的本质谱.采用半群方法和比较算子等方法,证明了对任意的t＞0,s＞0,算子[UH（t）-U0（t）]U0（s）[UH（t）-U0（t）]在Lp（1＜p＜＋∞）在空间中紧和在L1空间弱紧,得到迁移半群VH（t）与V0（t）有相同的本质谱型.     

Musielak—Orlicz空间L^p（x）（Ω）的若干凸性

本文研究了一类特殊的Musielak-Orlicz空间Lp(x)(Ω)赋予Luxemburg范数时的严格凸性,局部一致凸性,弱局部一致凸性,中点局部一致凸性与一致凸性.利用Banach空间几何学中刻画凸性的一般方法,并结合一般Musielak-Orlicz空间凸性的判别准则,获得了用p(x)刻画空间Lp(x)(Ω)赋予Luxemburg范数时,上述几种凸性的充分必要条件.     

p-仿紧空间

本文研究了p-仿紧空间和p-可数仿紧空间的相关问题.利用预开集和覆盖性质理论,得到了p-仿紧空间和p-可数仿紧空间的定义、等价刻画及αp-仿紧子集的性质,推广了一般拓扑学中仿紧空间的部分结果.     

FC-度量空间中的R-KKM定理及其对变分不等式和不动点的应用

引入了FC-度量空间,建立了非紧FC-度量空间中的R-KKM定理.作为应用,研究了非紧FC-度量空间中的变分不等式的解集、相交点集、Ky Fan截口和极大元集的性质,获得了FC-度量空间中的Fan-Browder不动点定理.     

L_Δ-闭包空间的Δ-仿紧性

在L_Δ-闭包空间中借助于L_α-Δ-开覆盖、α-局部有限集族、α--局部有限集族引入了Δ-仿紧性.证明了它对Δ-闭集是遗传的、Δ-紧的L_Δ-闭包空间和Δ-仿紧空间的积空间是Δ-仿紧的重要性质.     

HORMANDER MULTIPLIER THEOREM ON SU(2)

ＨＲＡＮＤＥＲＭＵＬＴＩＰＬＩＥＲＴＨＥＯＲＥＭＯＮＳＵ（２）￥ＦＡＮＤＡＳＨＡＮ；ＸＵＺＥＮＧＦＵ（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｈｅｍａｔｉｃｓ，ＡｕｈｕｉＵｎｉｖｅｒｓｉｔｙｔＨｅｆｅｉ２３００３９，Ｃｈｉｎａ．）Ａｂｓｔｒａｃｔ：Ａｂｏｕｎｄ...     

James sequences and Dependent Choices

We prove James's sequential characterization of (compact) reflexivity in set‐theory ZF + DC , where DC is the axiom of Dependent Choices. In turn, James's criterion implies that every infinite set is Dedekind‐infinite, whence it is not provable in ZF . Our proof in ZF + DC of James' criterion leads us to various notions of reflexivity which are equivalent in ZFC but are not equivalent in ZF . We also show that the weak compactness of the closed unit ball of a (simply) reflexive space does not imply the Boolean Prime Ideal theorem : this solves a question raised in [6]. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

二元尺度函数的正交性

本文从非诱导的二维正交滤波的一类零点出发，构造紧集Ｋ，利用Ｃｏｈｅｎ准则，得到非诱导滤波对应的（Ａ，ｈ）尺度函数正交的一个充分条件，并构造二维正交滤波的例子说明其应用．     

Strictly positive definite functions on the unit circle

We study strictly positive definite functions on the unit circle in the Euclidean space of dimension two. We develop several conditions pertaining to the determination of such functions. The major result is obtained by considering the set of real numbers as a vector space over the field of rational numbers and then applying the Kronecker approximation theorem and Weyl's criterion on equidistributions.

     

A viability theorem for set-valued states in a Hilbert space

Applications in robust control problems and shape evolution motivate the mathematical interest in control problems whose states are compact (possibly non-convex) sets rather than vectors. This leads to evolutions in a basic set which can be supplied with a metric (like the well-established Pompeiu–Hausdorff distance), but it does not have an obvious linear structure. This article extends differential inclusions with state constraints to compact-valued states in a separable Hilbert space H. The focus is on sufficient conditions such that a given constraint set (of compact subsets) is viable a.k.a. weakly invariant. Our main result extends the tangential criterion in the well-known viability theorem (usually for differential inclusions in a vector space) to the metric space of non-empty compact subsets of H.     

Average cost Markov decision processes under the hypothesis of Doeblin

Average cost Markov decision processes (MDPs) with compact state and action spaces and bounded lower semicontinuous cost functions are considered. Kurano [7] has treated the general case in which several ergodic classes and a transient set are permitted for the Markov process induced by any randomized stationary policy under the hypothesis of Doeblin and showed the existence of a minimum pair of state and policy. This paper considers the same case as that discussed in Kurano [7] and proves some new results which give the existence theorem of an optimal stationary policy under some reasonable conditions.     

Subseries Convergence and Unconditionally Convergence of Compact Operator Series

Let(E,r)bealocallyconvexHausdorfftopologicalvectorspace.AseriesZxiinEissaidtobesubseriesr-convergent(-s.c.),ifforeachstrictlyincreasingsequence{n,}inN,theseriesZx"'isT-convergent.TheseriesZx,issaidtobeunconditionallyr-convergent(r-u.c.),ifforeachpermutationffofN,theseriesZx,<,,ls.,r-convergence.rheseriesZx,issaidtobesubseriesunconditional1yT-convergent(r-s.u.c.)ifforeachstrictlyincreasingseqtience{n,}inN,theseriesZx.,isunconditionallyr-convergent.If(E,r)isasequentiallycompletespace,thenT…     

Return times theorem for amenable groups

We extend Bourgain’s return times theorem to arbitrary locally compact second countable amenable groups. The proof is based on a version of the Bourgain-Furstenberg-Katznelson-Ornstein orthogonality criterion.     

A Generalized Fejér’s Theorem for Locally Compact Groups

The classical Fejér’s theorem is a criterion for pointwise convergence of Fourier series on the unit circle. We generalize it to locally compact groups.