概率赋范空间上的线性算子

本文提出了概率赋范空间上各类线性算子的概念,并仔细研究了它们之间的关系。     

概率线性赋范空间与随机算子

本文进一步研究概率线性赋范空间中随机算子的理论,本文的结果改进和发展了最近林熙[1],以及[4]中的某些主要结果。     

赋范线性空间中的列收敛

本文证明了Ｓｃｈｕｒ空间与有限维Ｂａｎａｃｈ空间的两个特征定理，并对赋范线性空间中的列收敛进行了讨论，得到了一些有趣的结果。     

概率赋范空间中的一致凸性

该文在概率赋范空间中引进了“单位球”和“一致凸”的概念,证明了“最佳近似元”的存在性和唯一性。     

概率赋准范空间中的连续算子

运用概率度量的思想在PQN空间下讨论连续算子,研究了连续算子的有界性.主要得出了两个研究结论:1)在一定条件下,两个PQN空间之间的连续算子构成一个拓扑线性空间.2) PQN空间中算子的连续性和有界性(拓扑有界)不等价,在一定条件下,算子的连续性可以推导出其有界性(拓扑有界),但是反之不成立.     

概率赋范线性空间的不动点定理

概率度量空间(简称 PM 空间)是1942年 Menger[1]首先提出的,它是用一个分布函数表示任意两点间距离的空间.由于在许多情况下,集合中两元间距离具有随机性,这时用概率度量(即用一个分布函数表示距离)比用通常的度量(即用一个实数表示距离)更符合客观实际,因此研究 PM 空间具有重要意义。基于类似的思想,1963年 Serstnev[2]提出了概率赋范线性空间([2]中称为随机赋范空间)的概念,后来,Bocsan[3],Dumitrescu[4]等也做了一些研究工作,但和概率     

概率赋范空间的线性拓扑性质

本文首先扩充了概率赋范空间(probabilistic normed space,简记为PNS)的定义,然后着重研究了它们的线性拓扑性质,所得到的结果不仅包含[3]和[4]中的结果为特例,而且较为彻底地阐明了PNS与赋准范空间、赋B_0型准范空间、以及赋范空间的关系。     

关于PN空间上线性算子的概率范数

本文提出PN空间上线性算子的概率范数的新定义,并用它对算子有界性进行刻划,还讨论了算子空间的完备性.     

关于线性算子的概率范数与算子空间

由于满足(PN-5)条件的PN空间(E,F)就是MangerPN空间(E,F,min),因此,肖建中等给出的关于PN空间上线性算子概率范数的结果有较大的局限性.本文中,在较一般的MengerPN空间上研究有关线性算子的概率范数和算子空间的问题,改进和推广了肖建中等的结果.     

On Uniform Convergence of Sequences of Certain Linear Operators

The paper is devoted to the study of the uniform convergence of -summations of Fourier series and discrete Fourier series. We show that by choosing different parameters of these operators different orders of the uniform convergence can be attained on the space C ₂.     

Statistically Relatively Uniform Convergence of Positive Linear Operators

In this paper we define a new type of statistical convergence by using the notions of the natural density and the relatively uniform convergence. We study its use in the Korovkin-type approximation theory. Then, we construct an example such that our new approximation result works but its classical and statistical cases do not work. We also compute the rates of statistically relatively uniform convergence of sequences of positive linear operators.     

Approximation Numbers of Operators on Normed Linear Spaces

In [1], B?ttcher et. al. showed that if T is a bounded linear operator on a separable Hilbert space H, {e_j}_j=1^￥H, \{e_{j}\}_{j=1}^{\infty} is an orthonormal basis of H and P_n is the orthogonal projection onto the span of {e_j}_j=1ⁿ\{e_{j}\}_{j=1}^{n}, then for each k ? \mathbbNk \in {\mathbb{N}}, the sequence {s_k(P_nTP_n)}\{s_{k}(P_{n}TP_{n})\} converges to s_k(T), where for a bounded operator A on H, s_k(A) denotes the kth approximation number of A, that is, s_k(A) is the distance from A to the set of all bounded linear operators of rank at most k − 1. In this paper we extend the above result to more general cases. In particular, we prove that if T is a bounded linear operator from a separable normed linear space X to a reflexive Banach space Y and if {P_n} and {Q_n} are sequences of bounded linear operators on X and Y, respectively, such that ||P_n|| ||Q_n|| ￡ 1\|P_n\| \|Q_n\| \leq 1 for all n ? \mathbbNn \in {\mathbb{N}} and {Q_nTP_n} converges to T under the weak operator topology, then {s_k(Q_nTP_n)}\{s_{k}(Q_{n}TP_{n})\} converges to s_k(T). We also obtain a similar result for the case of any normed linear space Y which is the dual of some separable normed linear space. For compact operators, we give this convergence of s_k(Q_nTP_n)s_{k}(Q_{n}TP_{n}) to s_k(T) with separability assumptions on X and the dual of Y. Counter examples are given to show that the results do not hold if additional assumptions on the space Y are removed. Under separability assumptions on X and Y, we also show that if there exist sequences of bounded linear operators {P_n} and {Q_n} on X and Y respectively such that (i) Q_nTP_nQ_{n}TP_{n} is compact, (ii) ||P_n|| ||Q_n|| ￡ 1\|P_{n}\| \|Q_{n}\| \leq 1 and (iii) {Q_nTP_n}\{Q_{n}TP_{n}\} converges to T in the weak operator topology, then {s_k(Q_nTP_n)}\{s_k(Q_{n}TP_{n})\} converges to s_k(T) if and only if s_k(T) = s_k(T￠)s_{k}(T) = s_{k}(T^\prime). This leads to a generalization of a result of Hutton [3], proved for compact operators between normed linear spaces.     

On The Spaces of Linear Operators Acting Between Asymmetric Cone Normed Spaces

An asymmetric norm is a positive sublinear functional p on a real vector space X satisfying \(x=\theta _X\) whenever \(p(x)=p(-x)=0\). Since the space of all lower semi-continuous linear functionals of an asymmetric normed space is not a linear space, the theory is different in the asymmetric case. The main purpose of this study is to define bounded and continuous linear operators acting between asymmetric cone normed spaces. After examining the differences with symmetric case, we give some results related to Baire’s characterization of completeness in asymmetric cone normed spaces.     

Geometric Properties Characteristic of Normed Linear Space

This paper provides new characterizations of arbitrary, not necessarily rotund, normed linear spaces, using triangle median properties and weakened forms of associativity and the consistent midpoint property. Connections are explored between the methods used here and a characterization announced by ARONSZAJN in 1935.     

关于赋范线性空间中增生算子方程的逼近问题

研究了赋范线性空间中强增生映射和一致增生映射的零点的最速下降法迭代逼近问题,修正了Chidume的一个定理,改进和推广了Chidume和周海云等近期的相应结果.