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H中G-框架等式

框架已获得广泛的应用,g-框架是框架的推广.本文运用算子理论方法,根据Hilbert空间H中的g-框架和g-框架算子的性质,得到有关g-框架的几个等式,给出一些有意义的结果.     

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.     

Hilbert C~*-模上的广义g-框架

本文主要研究了Hilbert C~*-模上广义g-框架.给出了Hilbert C~*-模上的广义g-框架,广义g-框架算子,广义典则对偶g-框架及广义交错对偶g-框架的定义,并证明了有关广义g-框架的一些结果.     

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.     

Hilbert C~*-模中g-框架的一些性质

本文运用算子理论方法,给出Hilbert C~*-模中g-框架的一些性质并讨论g-框架的扰动性,得到g-框架的和的一些刻画,所得结果推广和改进了已有的结果.     

Hilbert空间中g-Parseval框架的一些性质

在Hilbert空间中讨论g-Parseval框架的一些性质,得到g-Parseval框架的一些恒等式和不等式.     

K-g-框架与子空间对偶g-框架

在Hilbert空间中定义K-g-框架,探讨K-g-框架与g-框架的一些本质差别.利用特殊闭子空间的对偶g-框架来刻画K-g-框架,给出构造特殊闭子空间对偶g-框架的一种方法,并介绍相关的K-g-框架的一些性质.     

g-框架的一些新性质

考虑了g-框架的一些新性质.首先把有关框架的投影方法推广到g-框架,并且建立了一个类似的该方法对g-框架有效的充分必要条件.然后研究了包含g-Riesz基的g-框架,得到了在某些条件下g-Riesz框架一定包含g-Riesz基.我们提出了具有子g-框架性质的g-框架的概念,证明了在某些条件下具有子g-框架性质的g-框架一定包含一个g-Riesz基.最后得到了一些g-框架与其诱导出的框架之间的在某些限制条件下的等价性质.     

广义框架的一些等式和不等式

广义框架是框架的推广,它包含了Hilbert空间中通常框架的最近各种拓广.建立广义框架的一些等式和不等式.所得结果推广和改进了Balan R.,Casazza P G.,Edidin D.和Kutyniok G.的结果.特别地,说明了不等式中的界是最佳的.     

Exact g-frames in Hilbert spaces

G-frames, which were considered recently as generalized frames in Hilbert spaces, have many properties similar to those of frames, but not all the properties are similar. For example, exact frames are equivalent to Riesz bases, but exact g-frames are not equivalent to g-Riesz bases. In this paper, we firstly give a characterization of an exact g-frame in a complex Hilbert space. We also obtain an equivalent relation between an exact g-frame and a g-Riesz basis under some conditions. Lastly we consider the stability of an exact g-frame for a Hilbert space under perturbation. These properties of exact g-frames for Hilbert spaces are not similar to those of exact frames.     

On sum and stability of g-frames in Hilbert spaces

In this paper, we give some new results on sum and stability of g-frames in Hilbert spaces. Since the finite sum of g-frames may not be a g-frame for the Hilbert space, we give a necessary and sufficient condition and some sufficient conditions for the finite sum of g-frames to be a g-frame. We also show that every g-sequence in Hilbert space can be expanded to a tight g-frame by adding a linear bounded operator. Moreover, we obtain some sufficient conditions under which g-frames (and the finite sum of g-frames) are stable under small perturbations.     

Stability of g-frames

g-Frames are natural generalizations of frames which cover many other recent generalizations of frames, e.g., bounded quasi-projectors, frames of subspaces, outer frames, oblique frames, pseudo-frames and a class of time-frequency localization operators. Moreover, it is known that g-frames are equivalent to stable space splittings. In this paper, we study the stability of g-frames. We first present some properties for g-Bessel sequences. Then we prove that g-frames are stable under small perturbations. We also study the stability of dual g-frames.     

Approximate duality of g-frames in Hilbert spaces

In this article, we introduce and characterize approximate duality for g-frames. We get some important properties and applications of approximate duals. We also obtain some new results in approximate duality of frames, and generalize some of the known results in approximate duality of frames to g-frames. We also get some results for fusion frames, and perturbation of approximately dual g-frames. We show that approximate duals are stable under small perturbations and they are useful for erasures and reconstruction.     

APPROXIMATE DUALITY OF g-FRAMES IN HILBERT SPACES

In this article, we introduce and characterize approximate duality for g-frames. We get some important properties and applications of approximate duals. We also obtain some new results in approximate duality of frames, and generalize some of the known results in approximate duality of frames to g-frames. We also get some results for fusion frames, and perturbation of approximately dual g-frames. We show that approximate duals are stable under small perturbations and they are useful for erasures and reconstruction.     

SOME PROPERTIES OF OPERATOR-VALUED FRAMES

Operator-valued frames(or g-frames) are generalizations of frames and fusion frames and have been used in packets encoding, quantum computing, theory of coherent states and more. In this article, we give a new formula for operator-valued frames for finite dimensional Hilbert spaces. As an application, we derive in a simple manner a recent result of A. Najati concerning the approximation of g-frames by Parseval ones. We obtain also some results concerning the best approximation of operator-valued frames by its alternate duals,with optimal estimates.     

Hilbert 空间中的广义正交基

广义正交基是Hilbert 空间中正交基的一个自然推广. 本文首先给出一个广义正交基存在的较弱的充要条件; 然后研究广义正交基的性质, 特别地, 得到广义正交基版本的一些有关正交基的经典性质, 如广义正交基的Bessel 等式和不等式等. 作为广义正交基的一个应用, 本文给出广义Riesz 基的一些新刻画. 最后本文讨论广义框架的冗余问题.     

G-frames and g-Riesz bases

G-frames are generalized frames which include ordinary frames, bounded invertible linear operators, as well as many recent generalizations of frames, e.g., bounded quasi-projectors and frames of subspaces. G-frames are natural generalizations of frames and provide more choices on analyzing functions from frame expansion coefficients. We give characterizations of g-frames and prove that g-frames share many useful properties with frames. We also give a generalized version of Riesz bases and orthonormal bases. As an application, we get atomic resolutions for bounded linear operators.