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预框架算子是算子理论应用于框架理论研究中的一个重要算子.在本文中我们将讨论预框架算子在Hilbert空间的框架构造以及框架变换和对偶框架方面的一些应用.特别地,我们得到了Hilbert空间上两框架之和是和空间上的框架以及保持框架与对偶框架某些性质的变换的算子论刻画. 相似文献
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本文研究了可分的Hilbert空间H中带符号广义框架,利用算子理论方法,给出了H中一族向量{hm}m∈M是一个带符号广义框架当且仅当带符号广义框架的框架算子的正部S 和负部S-是有界线性算子,讨论了H中带符号广义框架的框架算子S的可逆性,并且得到了H中每个向量f关于带符号广义框架{hm}m∈M和其对偶带符号广义框架{~hm}m∈M的表示式. 相似文献
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研究了算子子空间的渐近自反性问题,渐近自反子空间的遗传斯近自反性以及某些单个算子的渐近自反性.我们也讨论了投影网类的浙近自反性。 相似文献
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李岚 《纯粹数学与应用数学》2008,24(2)
算子框架是广义的框架,它包括框架序列和子空间框架.本文分别讨论了在Bessel算子列和算子框架的扰动下,其对偶框架的稳定性.得到了一些新结果,这些结果是序列框架稳定性的推广. 相似文献
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具有Gauss测度的Sobolev空间上的函数逼近 总被引:1,自引:0,他引:1
本文讨论了具有Gauss测度的Sobolev空间上的一元周期函数被三角多项式子空间的最佳逼近及被Fourier部分和算子,Vallée—Poussin算子,Ceshxo算子,Abel算子和Jackson算子的逼近,得到了平均误差估计.证明了在平均框架下,在Lq(1≤q〈∞)空间尺度下三角多项式子空间是渐进最优的子空间,但是在L∞空间尺度下,三角多项式子空间不是渐进最优的子空间.还证明了,Fourier部分和算子和Vallée-Poussin算子在Lq(1≤q≤∞)空间尺度下是渐进最优的线性算子.注意到在平均框架以及Lq(1≤q〈∞)空间尺度下,渐进最优的线性算子,如Fourier部分和算子及Vallée—Poussin算子,与最优的非线性算子的逼近效果一样好. 相似文献
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研究了算子空间的原子性.证明了算子空间V是原子当且仅当V是正合且有限内射; V内的任意一个有限维算子子空间是原子当且仅当V是原子且V内任意有限维算子子空间足V的完全补.因此作为推论,得到了无限维箅子空间V的任意有限维子空间是原子,则V是1-Hilbertian和1-齐次. 相似文献
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We first present a formula for the supremum cosine angle between two closed subspaces of a separable Hilbert space under the assumption that the ‘generators’ form frames for the subspaces. We then characterize the conditions that the sum of two, not necessarily finitely generated, shift-invariant subspaces of L2(Rd) be closed. If the fibers of the generating sets of the shift-invariant subspaces form frames for the fiber spaces a.e., which is satisfied if the shift-invariant subspaces are finitely generated or if the shifts of the generating sets form frames for the respective subspaces, then the characterization is given in terms of the norms of possibly infinite matrices. In particular, if the shift-invariant subspaces are finitely generated, then the characterization is given wholly in terms of the norms of finite matrices. 相似文献
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Mariano A. Ruiz Demetrio Stojanoff 《Journal of Mathematical Analysis and Applications》2008,343(1):366-378
We study the relationship among operators, orthonormal basis of subspaces and frames of subspaces (also called fusion frames) for a separable Hilbert space H. We get sufficient conditions on an orthonormal basis of subspaces E={Ei}i∈I of a Hilbert space K and a surjective T∈L(K,H) in order that {T(Ei)}i∈I is a frame of subspaces with respect to a computable sequence of weights. We also obtain generalizations of results in [J.A. Antezana, G. Corach, M. Ruiz, D. Stojanoff, Oblique projections and frames, Proc. Amer. Math. Soc. 134 (2006) 1031-1037], which relate frames of subspaces (including the computation of their weights) and oblique projections. The notion of refinement of a fusion frame is defined and used to obtain results about the excess of such frames. We study the set of admissible weights for a generating sequence of subspaces. Several examples are given. 相似文献
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ON THE STABILITY OF FUSION FRAMES (FRAMES OF SUBSPACES) 总被引:1,自引:0,他引:1
Mohammad Sadegh Asgari 《数学物理学报(B辑英文版)》2011,31(4):1633-1642
A frame is an orthonormal basis-like collection of vectors in a Hilbert space, but need not be a basis or orthonormal. A fusion frame (frame of subspaces) is a frame-like collection of subspaces in a Hilbert space, thereby constructing a frame for the whole space by joining sequences of frames for subspaces. Moreover the notion of fusion frames provide a framework for applications and providing efficient and robust information processing algorithms.In this paper we study the conditions under which removing an element from a fusion frame, again we obtain another fusion frame. We give another proof of [5, Corollary 3.3(iii)] with extra information about the bounds. 相似文献
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Wavelet frames for (not necessarily reducing) affine subspaces II: The structure of affine subspaces
This is a continuation of the investigation into the theory of wavelet frames for general affine subspaces. The main focus of this paper is on the structural properties of affine subspaces. We show that every affine subspace is the orthogonal direct sum of at most three purely non-reducing subspaces, while every reducing subspace (with respect to the dilation and translation operators) is the orthogonal direct sum of two purely non-reducing ones. This result is obtained through considering the basic question as to when the orthogonal complement of an affine subspace in another one is still affine. Motivated by the fundamental question as to whether every affine subspace is singly-generated, and by a recent result that every singly generated purely non-reducing subspace admits a singly generated wavelet frame, we prove that every affine subspace can be decomposed into the direct sum of a singly generated affine subspace and some space of “small size”. As a consequence we establish a connection between the above mentioned two questions. 相似文献
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本给出并证明了若干个子空间的并以及两个子空间的基构成子空间的充要条件,从而本质地揭示了除子空间的交与和是构造新的予空间的方法外,集合的其它运算不能构造新的子空间,最后分析了子空间直和的两种不同定义的优缺点,指出了张禾瑞教材中子空间直和定义推广时应注意的一个问题。 相似文献
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A general approach based on polyphase splines, with analysis in the frequency domain, is developed for studying wavelet frames of periodic functions of one or higher dimensions. Characterizations of frames for shift-invariant subspaces of periodic functions and results on the structure of these subspaces are obtained. Starting from any multiresolution analysis, a constructive proof is provided for the existence of a normalized tight wavelet frame. The construction gives the minimum number of wavelets required. As an illustration of the approach developed, the one-dimensional dyadic case is further discussed in detail, concluding with a concrete example of trigonometric polynomial wavelet frames. 相似文献
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GUO Hui 《中国科学A辑(英文版)》2000,43(1):47-58
A new kind of subspaces of the universal Teichmüller space is introduced. Some characterizations of the subspaces are given in terms of univalent functions, Beltrami coefficients and quasisymmetric homeomorphisms of the boundary of the unit disc. 相似文献
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Somantika Datta 《Linear and Multilinear Algebra》2016,64(8):1484-1497
Lower bounds on the maximal cross correlation between vectors in a set were first given by Welch and then studied by several others. In this work, this is extended to obtaining lower bounds on the maximal cross correlation between subspaces of a given Hilbert space. Two different notions of cross correlation among spaces have been considered. The study of such bounds is done in terms of fusion frames, including generalized fusion frames. In addition, results on the expectation of the cross correlation among random vectors have been obtained. 相似文献
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In a wide class of weighted Bergman spaces, we construct invertible non-cyclic elements. These are then used to produce z-invariant subspaces of index higher than one. In addition, these elements generate non-trivial bilaterally invariant subspaces in anti-symmetrically weighted Hilbert spaces of sequences. 相似文献