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。     

Best Interpolatory Approximation in Normed Linear Spaces

A theory of best approximation with interpolatory contraints from a finite-dimensional subspaceMof a normed linear spaceXis developed. In particular, to eachxX, best approximations are sought from a subsetM(x) ofMwhichdependson the elementxbeing approximated. It is shown that this “parametric approximation” problem can be essentially reduced to the “usual” one involving a certainfixedsubspaceM₀ofM. More detailed results can be obtained when (1) Xis a Hilbert space, or (2) Mis an “interpolating subspace” ofX(in the sense of [1]).     

On the Best Approximation in Non-Archimedean Normed Linear Spaces

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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.     

Approximation Numbers of Identity Operators between Symmetric Sequence Spaces

We prove asymptotic formulas for the behavior of approximation quantities of identity operators between symmetric sequence spaces. These formulas extend recent results of Defant, Masty o, and Michels for identities l_pⁿF_n with an n-dimensional symmetric normed space F_n with p-concavity conditions on F_n and 1p2. We consider the general case of identities E_nF_n with weak assumptions on the asymptotic behavior of the fundamental sequences of the n-dimensional symmetric spaces E_n and F_n. We give applications to Lorentz and Orlicz sequence spaces, again considerably generalizing results of Pietsch, Defant, Masty o, and Michels.     

模糊赋范线性空间中准齐性算子族的等度连续性

在模糊赋范线性空间中研究点态模糊有界的准齐性算子族的等度连续性, 并且建立点态模糊半有界与点态非模糊无界的准齐性算子族的共鸣定理.作为其推论, 得到了经典的赋范线性空间和Menger概率赋范线性空间中相应的结论.     

赋范线性空间上有界线性泛函的一般形式

1968年,N.E.Gretsky求得了Banach函数空间上有界线性泛函的一般形式。1977年,G.D.Faulkner对自反的Banach空间解决了这个问题。又本文作者对一类无限多个Banach空间解决了有界线性泛函的表示问题。 本文对一般的赋范线性空间给出了有界线性泛函的表达式和共轭空间的等距同构表现。     

On the Compactness and Approximation Numbers of Hardy-Type Integral Operators in Lorentz Spaces

We characterize the mapping properties such as the boundedness,compactness and measure of noncompactness for those real weightfunctions , , u0, v0, for which the Hardy-type integral operatorof the form acts from to , when the parameters are restricted to the range 1 < max (r,s) min (p, q) < and the kernel k(x, y) 0 satisfies theOinarov condition (see (2) below). For the case k(x, y) = 1,we obtain lower and upper estimates of the approximation numbers,extending the result of [5].     

赋范线性空间中的Hilbert型积分不等式

基于利用一个积分恒等式的新技巧,建立了赋范线性空间中新的Hilbert型积分不等式.这些新的结果包含了n维欧氏空间中n重积分的Hilbert型积分不等式作为其特殊情形.     

The Approximation Numbers of Hardy-Type Operators on Trees

The Hardy operator T_a on a tree is defined by Properties of T_a as a map from L^p() into itselfare established for 1 p . The main result is that, with appropriateassumptions on u and v, the approximation numbers a_n(T_a) ofT_a satisfy for a specified constant _p and 1 p < . This extends results of Naimark, Newmanand Solomyak for p = 2. Hitherto, for p 2, (*) was unknowneven when is an interval. Also, upper and lower estimates forthe l^q and weak-l^q norms of a_n(T_a) are determined. 2000 MathematicalSubject Classification: 47G10, 47B10.     

About Approximation Numbers in Function Spaces

Sharp estimates for the approximation numbers of embeddings between the function spacesB^s_pqandF^s_pqon domains are given in a case not thoroughly studied by Edmunds and Triebel. Corresponding sharp estimates are also obtained for the counterparts of that case in the weighted function space setting.     

Local Solarity of Suns in Normed Linear Spaces

The paper is concerned with solarity of intersections of suns with bars (in particular, with closed balls and extreme hyperstrips) in normed linear spaces. A sun in a finite-dimensional (BM)-space (in particular, in ? ¹(n)) is shown to be monotone path connected. A nonempty intersection of an m-connected set (in particular, a sun in a two-dimensional space or in a finite-dimensional (BM)-space) with a bar is shown to be a monotone path-connected sun. Similar results are obtained for boundedly compact subsets of infinite-dimensional spaces. A nonempty intersection of a monotone path-connected subset of a normed space with a bar is shown to be a monotone path-connected α-sun.     

关于线性赋范空间的三个几何参数

In this paper we introduce the following definitions. Definition 3. For normed liner spaces X (dim X≥2), a mapping φ:X→φ(x)∈R is said to be an abstract parameter if φ(X)=φ(Y) whenever X and Y are isome-trically isomorphic normed linear spaces.     

赋范线性空间的第二对偶空间

Theorem. A mapping x^** of X^* into sealar field Φ is a linear functional if and only if there exists a μ∈ba(S) such that X^**(X^*)=∫_sx^*(s)μ(ds),x^*∈X^* Theorem. F∈ba(S.Σ)^* if and only if there exists a λ∈ba (T) (T is the closed unit sphere of the space B(S,Σ))such that F(μ)=∫(∫_st(s)μ(ds))λ(dt),μ∈ba(S,Σ).     

Angles of Norm ed Linear Spaces and Characterizations of Inner Product Spaces

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Approximation and Extension in Normed Spaces of Infinitely Differentiable Functions

We consider questions of rational and polynomial approximation,and related extension questions, for various normed spaces ofinfinitely differentiable functions on perfect compact subsetsof the complex plane C and the real line R. We obtain an approximationtheorem for compact planar sets which are, in a precise sense,locally radially self-absorbing. All smoothly-bounded compactsets are of this type. We give a variety of results and counterexampleson extension, mainly in the one-dimensional case. We also provepolynomial approximation theorems for totally-disconnected sets,linear sets, and some others.     

实赋范空间上的某些类连续线性泛函

在实赋范空间上通过范数导数（左、右两个）引进一种广义内积（上、下两个），并用它们对实赋范空间上的线性连续泛函给出上、下估计式。本文主要结果揭示了实赋范空间上的如下三类连续线性泛函的统一性。第一类连续线性泛函是指其中每一个ｆ都在闭单位球上取到其范数值ｆ。第二类连续线性泛函是指其中第一个ｆ的核Ｋｅｒ（ｆ）与另一空间元素之间的最佳逼近元存在。第三类连续性泛函是指其中每一个ｆ的上限和下限分别可用上、下两种