共查询到20条相似文献,搜索用时 375 毫秒
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本文对B(X,Y)的自反子空间及渐近自反子空间上的映射(或映射组),分别给出了一些判别它们的图象(或联合图象)仍为自反及渐近自反的方法。 相似文献
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关于非交换子空间格代数的超自反性 总被引:1,自引:0,他引:1
利用Arveson关于自反代数超自反的特征,给出Hilbert空间上一类非交换格自反代数超自反常数的一个估计,证明了一些非交换子空间格自反代数的超自反性. 相似文献
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自反Banach空间上算子代数的超自反性 总被引:4,自引:0,他引:4
本文引入自发Banach空间上算子代数A的超自反定义,讨论了A超自反的充要条件,超自反常数的估计以及超自反在代数同构下的不变性。 相似文献
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定义了子空间格代数的(弱闭双边)模,对有限维Hilbert空间的强自反子空间格代数的模及原子Boolean格代数的模中的有限秩算子进行了讨论,得到有限秩算子一定可以表示为秩1算子的和. 相似文献
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Hassan Yousefi 《Journal of Functional Analysis》2006,237(1):321-337
We prove some new results on Hadwin's general version of reflexivity that reduce the study of E-reflexivity (or E-hyperreflexivity) of a linear subspace to a smaller linear subspace. By applying our abstract results, we present a simple proof of D. Hadwin's theorem, which states that every C∗-algebra is approximately hyperreflexive. We also prove that the image of any C∗-algebra under any bounded unital homomorphism into the operators on a Banach space is approximately reflexive. We introduce a new version of reflexivity, called approximate algebraic reflexivity, and study its properties. 相似文献
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This paper extends the theory of reflexivity triples by extending notions and results in the theory of dual operator algebras to this more general setting. In addition, a complete and simple characterization is given for the reflexivity of two-dimensional pattern spaces of finite matrices. 相似文献
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This paper extends the theory of reflexivity triples by extending notions and results in the theory of dual operator algebras to this more general setting. In addition, a complete and simple characterization is given for the reflexivity of two-dimensional pattern spaces of finite matrices. 相似文献
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In this paper, we study two types of approximate solutions for a vector optimization problem in Banach space setting. Our main concern is to define two new concepts of approximate saddle points and relate them to the above solution concepts. As a result, a dual is formulated, and duality results are established. 相似文献
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In this paper, we introduce the concept of approximate solutions for set-valued mappings and provide a sufficient condition
for the existence of approximate solutions of set-valued mappings. We obtain an approximate variational principle for set-valued
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Revised version received November 1997 相似文献
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Solution of large linear systems encountered in computational fluid dynamics often naturally leads to some form of domain decomposition, especially when it is desired to use parallel machines. It has been proposed to use approximate solvers to obtain fast but rough solutions on the separate subdomains. In this paper approximate solutions via (1) an inner preconditioned GMRES iteration to fixed tolerance, and (2) incomplete factorization (RILU, restricted to the diagonal) are considered. Numerical experiments for a fundamental test problem are included which show speedups obtained on a cluster of workstations as well as on a distributed memory parallel computer. Additionally, the parallel implementation of GCR is addressed, with particular focus on communication costs associated with orthogonalization processes. This consideration brings up questions concerning the use of Householder reflections with GCR. 相似文献
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Amer Kaebi Asghar Kerayechian Faezeh Toutounian 《Applied mathematics and computation》2005,170(2):638-1076
This paper presents a new method for obtaining a matrix M which is an approximate inverse preconditioner for a given matrix A, where the eigenvalues of A all either have negative real parts or all have positive real parts. This method is based on the approximate solution of the special Sylvester equation AX + XA = 2I. We use a Krylov subspace method for obtaining an approximate solution of this Sylvester matrix equation which is based on the Arnoldi algorithm and on an integral formula. The computation of the preconditioner can be carried out in parallel and its implementation requires only the solution of very simple and small Sylvester equations. The sparsity of the preconditioner is preserved by using a proper dropping strategy. Some numerical experiments on test matrices from Harwell–Boing collection for comparing the numerical performance of the new method with an available well-known algorithm are presented. 相似文献
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A comparative study of approximate symmetry and approximate homotopy symmetry to a class of perturbed nonlinear wave equations is performed. First, complete infinite-order approximate symmetry classification of the equation is obtained by means of the method originated by Fushchich and Shtelen. An optimal system of one-dimensional subalgebras is derived and used to construct general formulas of approximate symmetry reductions and similarity solutions. Second, we study approximate homotopy symmetry of the equation and construct connections between the two symmetry methods for the first-order and higher-order cases, respectively. The series solutions derived by the two methods are compared. 相似文献
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1.引言为了用有限维常微分方程来研究Navier七lobes(N七)方程的长时间动力学行为,Foias,Sell和Temaml]引入了耗散系统惯性流形的概念.但惯性流形存在的一个相当苛刻的条件一谱间隔条件一是包括N习方程在内的很多耗散系统无法满足的.因此,Foias,Manlea和TemamZ]随后又提出了近似惯性流形的概念.近似惯性流形也是一个光滑的Lipschitz流形,所有原方程的解在时间充分大时,将被吸引进入该流形的一个三邻域中.因其存在性不需要谱间隔条件来保证,从而可证明包括N-S方程在内的一大类耗散系统存在近似惯性流形.利用近似惯性… 相似文献
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基于命题逻辑公式之间相似度的概念,在经典命题逻辑系统中提出了两种近似推理模式,得到了它们的一些基本性质。讨论了这两种推理模式与经典推理模式之间的关系。此外,当理论Γ有限时,本文分别给出Γ在α程度上近似推出公式A和理论Σ的充要条件。最后,我们给出公式A与有限理论Γ的结论集D(Γ)之间距离的计算公式。 相似文献