Hilbert空间中的紧K-框架

K-框架是框架的一种推广.本文在Hilbert空间将紧框架推广到K-框架上,引入紧K-框架的概念.通过紧K-框架的算子K和合成算子给出紧K-框架的算子刻画,并利用紧K-框架的算子K给出紧K-框架成为紧框架的一个充要条件.还讨论紧K-框架的构造以及两个紧K-框架集的包含与涉及的算子K的相互关系.     

Hilbert空间中的广义K-框架

通过引入广义K-框架和广义K-原子系统给出了Hilbert空间上有界线性算子K的值域的一种新的重构方式.广义K-框架是Hilbert空间中广义框架和K-框架概念的一种新的推广.为了建立基于广义K-框架的元素重构理论,广义K-对偶对和广义逼近K-对偶对的概念被引入.此外,广义K-框架和广义K-原子系统之间的关系,广义K-...     

K-框架和紧K-框架的算子扰动的稳定性

该文在Hilbert 空间中讨论K-框架和紧K-框架在算子扰动中的稳定性.首先给出K-框架经过有界线性算子T 扰动后为K-框架的充要条件,其次讨论了用两个Bessel 序列或者两个K-框架构造新的K-框架的方法,最后给出用两个Bessel 序列构造紧K-框架的充要条件.这些结果推广和改进了由Christensen和Ca...     

Hilbert空间中的K-g-框架的性质

在复Hilbert空间中定义了K-g-框架与K-g-Riesz基,探讨K-g-框架与g-框架的一些性质差别,并给出了K-g-Riesz基的等价刻画.利用分析与框架理论上的方法和技巧,研究了复Hilbert空间中K-g-框架与K-g-Riesz基扰动的稳定性,得到了K-g-框架与K-g-Riesz基满足扰动稳定性的充分条件.     

Hilbert空间中连续K-对偶的性质

文章引入Hilbert空间连续K-对偶,连续K-对偶对的概念,应用算子论的方法,讨论了Hilbert空间H上连续K-对偶和连续K-对偶对的若干性质及稳定性,并对已有文献的相关结论进行了推广.     

Hilbert K-模上酉群的框架表示

本文主要研究了Hilbert K-模上酉群的框架表示的一些基本性质，联系框架的强不相交性，得到了Hilbert K-模上酉群的框架表示的重数是有限的．     

Hilbert K-模上的广义框架变换和正交投影

本文引入了Hilbert K-模上的广义框架,广义框架变换和正交投影等概念,研究了广义标准正交基,广义(正规)紧框架(广义Bessel序列)的分解,得到了广义框架变换和正交投影之间的关系.     

Hilbert空间中的g-Riesz框架

g-框架作为Hilbert空间中的推广框架最近被提出,它们有许多和框架类似的性质,但并不是所有的性质都是相似的.Christensen已指出了每个Riesz框架都包含一个Riesz基.本文指出并不是所有的g-Riesz框架都包含一个g-Riesz基,但我们得到了每个g-Riesz框架都包含一个无冗g-框架,同时给出了H...     

Hilbert空间中的g-Besselian框架和拟g-Riesz基

在Hilbert空间中,g-框架作为框架的推广,具有许多类似于框架的性质,但并非所有的结论都类似.比如Besselian框架等价于拟Riesz基,但g-Besselian框架与拟g-Riesz基不等价.该文刻画了g-Besselian框架与拟g-Riesz基在一定条件下的等价关系;得到g-Besselian框架与拟g-Riesz基的对偶性结论;并在Hilbert空间中讨论g-Besselian框架与拟g-Riesz基的稳定性.     

K-非常凸空间

本文引入了一种新的K凸空间K-非常凸空间,及其对偶空间K-非常光滑空间,它们分别是非常凸空间和非常光滑空间的推广但又严格弱于非常凸空间和非常光滑空间,因此它们又有许多独特的性质.本文讨论了它们的一些特性及与其它K凸性和K光滑性的关系,推广了[3]、[6]、[7]、[8]中的一些结果.     

Some Properties of K-Frames in Hilbert Spaces

K-frames were recently introduced by G?vru?a in Hilbert spaces to study atomic systems with respect to a bounded linear operator. From her discussions there are many differences between K-frames and ordinary frames, so in this paper we further discuss the interchangeability of two Bessel sequences with respect to a K-frame, where K is a bounded linear operator with closed range. We also give several methods to construct K-frames. In the end we discuss the stability of a more general perturbation for K-frame.     

Scalar Derivatives in Hilbert Spaces

Computational formulae for scalar derivatives of mappings and pairs of mappings in the direction of a set will be given. These formulae are very important for explicitly verifying conditions of existence for fixed point theorems, surjectivity theorems, integral equations, variational inequalities and complementarity problems under additional differentiability conditions. To emphasize this idea at the end of the paper we give an application to complementarity problems. Some theorems which extend the correspondence between monotone mappings and scalar derivatives from Euclidean spaces to Hilbert spaces will also be given.     

Uncertainty Principles in Hilbert Spaces

In this article we provide several generalizations of inequalities bounding the commutator of two linear operators acting on a Hilbert space which relate to the Heisenberg uncertainty principle and time/frequency analysis of periodic functions. We develop conditions that ensure these inequalities are sharp and apply our results to concrete examples of importance in the literature.     

Feedback stabilizability in Hilbert Spaces

This paper is divided in four sections. In the first one, we recall the main notions related to the infinite dimensional control system such as the controllability and stability notions. The second section is devoted to a brief survey of the literature relevant to this paper. In the third section, we concentrate on the weak stabilizability of semigroups which are similar to contraction semigroups. The result presented here, which is believed to be new is that: IfA generates a semigroup which is similar to aC ₀ contraction semigroup, the system is weakly stabilizable if and only if the weakly unstable states of the system are approximately controllable. Finally, in the last section, we present two counterexamples showing the limitations of the weak stabilizability approach and discuss its possible extensions in view of some other fundamental problems.This research was supported in part by the United States Air Force Office of Scientific Research, Applied Mathematics Division, under Grant 73-2492     

Penalty Algorithms in Hilbert Spaces

We analyze the classical penalty algorithm for nonlinear programming in Hilbert spaces and obtain global convergence results, as well as asymptotic superlinear convergence order. These convergence results generalize similar results obtained for finite-dimensional problems. Moreover, the nature of the algorithms allows us to solve the unconstrained subproblems in finite-dimensional spaces.     

Finite-Dimensional Bicomplex Hilbert Spaces

This paper is a detailed study of finite-dimensional modules defined on bicomplex numbers. A number of results are proved on bicomplex square matrices, linear operators, orthogonal bases, self-adjoint operators and Hilbert spaces, including the spectral decomposition theorem. Applications to concepts relevant to quantum mechanics, like the evolution operator, are pointed out.     

Uniqueness for Integro-PDE in Hilbert Spaces

The paper deals with fully nonlinear integro-PDE of Hamilton-Jacobi-Bellman type with unbounded terms in infinite dimensional Hilbert spaces. A notion of viscosity solution is introduced for such integro-PDE and a general comparison theorem is proved.     

Hilbert空间中的斜对偶g-框架

在Hilbert空间中把斜对偶原理推广到更一般的g-框架.我们给出了{A_j:j∈J}是g-框架{F_j:j∈J}的一个斜对偶g-框架的等价条件,还给出了一个斜对偶g-框架对是对称的充分条件.最后,在不同的条件下构造了几对斜对偶g-框架.