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61.
Let M be a finite von Neumann algebra acting on a Hilbert space H and A be a transitive algebra containing M′. In this paper we prove that if A is 2-fold transitive, then A is strongly dense in B(H). This implies that if a transitive algebra containing a standard finite von Neumann algebra (in the sense of [U. Haagerup, The standard form of von Neumann algebras, Math. Scand. 37 (1975) 271-283]) is 2-fold transitive, then A is strongly dense in B(H). Non-selfadjoint algebras related to free products of finite von Neumann algebras, e.g., LFn and , are studied. Brown measures of certain operators in are explicitly computed. 相似文献
62.
As pointed out in [4] the paper [2], authored by G. Bennett, J. Boos and T. Leiger, contains a nontrivial gap in the argumentation
of the proof of Theorem 5.2 which is one of main results of that paper and has been applied three times. Till now neither
the gap is closed nor a counterexample has been stated. That is why the authors have examined in [4] the situation around
the ‘gap’ aiming to a better understanding for the gap. The aim of this paper is to prove the mentioned applications of the
theorem in doubt by using gliding hump arguments (quite similar to the classical proofs of the Theorems of Schur and Hahn
in the first case (cf. [3]) and a very technical and artful construction, being of independent mathematical interest, in the
second case).
Research of T. Leiger supported by Estonian Science Foundation Grant 5376. 相似文献
63.
On best simultaneous approximation in quotient spaces 总被引:1,自引:1,他引:0
M. Iranmanesh H. Mohebi 《分析论及其应用》2007,23(1):35-49
We assume that X is a normed linear space, W and M are subspaces of X. We develop a theory of best simultaneous approximation in quotient spaces and introduce equivalent assertions between the subspaces W and W + M and the quotient space W/M. 相似文献
64.
R. Srinivasan Puri Denise Morrey Andrew J. Bell John F. Durodola Evgenii B. Rudnyi Jan G Korvink 《Applied Mathematical Modelling》2009
A reduced order model is developed for low frequency, undamped, fully coupled structural–acoustic analysis of interior cavities backed by flexible structural systems. The reduced order model is obtained by applying a projection of the coupled system matrices, from a higher dimensional to a lower dimensional subspace, whilst preserving essential properties of the coupled system. The basis vectors for projection are computed efficiently using the Arnoldi algorithm, which generates an orthogonal basis for the Krylov Subspace containing moments of the original system. The key idea of constructing a reduced order model via Krylov Subspaces is to remove the uncontrollable, unobservable and weakly controllable, observable parts without affecting the transfer function of the coupled system. Three computational test cases are analyzed, and the computational gains and the accuracy compared with the direct inversion method in ANSYS. 相似文献
65.
利用伪辛空间上一类子空间m维(m,0,0,0)型子空间的性质构作了d~e析取矩阵M_q(2v+1,m,d),并利用子空间的计数定理计算了它的参数.通过研究N(m,0,0,0;2v+1)的单调性,得到了矩阵M_q(2v+1,m,d)的最优值. 相似文献
66.
We use the Weierstrass σ-function associated with a lattice in the complex plane to construct finite dimensional zero-based subspaces and quasi-invariant subspaces of given index in the Bargmann-Fock space. 相似文献
67.
城市综合实力增长的比较 总被引:7,自引:1,他引:6
本文基于多个总体的主成分分析方法,对城市综合实力增长的比较进行一些探索性的研究。对我国十八个大城市1994年、1995年和1996年的八个指标用多个总体的主成分分析方法进行分析,通过检验和计算,得到这三个总体的公共主成分子空间。取公共主成分子空间的一正交基作为这三个总体的新的主成分PRIN1的系数,此主成分即表示城市综合实力。计算出各城市任意两年间的综合实力差值,以此作为城市综合实力增长的度量,对城市综合实力增长再作主成分分析,即得到有效的城市综合实力增长的比较方法 相似文献
68.
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
69.
J. I. Aliaga D. L. Boley R. W. Freund V. Herná ndez. 《Mathematics of Computation》2000,69(232):1577-1601
Given a square matrix and single right and left starting vectors, the classical nonsymmetric Lanczos process generates two sequences of biorthogonal basis vectors for the right and left Krylov subspaces induced by the given matrix and vectors. In this paper, we propose a Lanczos-type algorithm that extends the classical Lanczos process for single starting vectors to multiple starting vectors. Given a square matrix and two blocks of right and left starting vectors, the algorithm generates two sequences of biorthogonal basis vectors for the right and left block Krylov subspaces induced by the given data. The algorithm can handle the most general case of right and left starting blocks of arbitrary sizes, while all previously proposed extensions of the Lanczos process are restricted to right and left starting blocks of identical sizes. Other features of our algorithm include a built-in deflation procedure to detect and delete linearly dependent vectors in the block Krylov sequences, and the option to employ look-ahead to remedy the potential breakdowns that may occur in nonsymmetric Lanczos-type methods.
70.
This paper studies the structure of shift-invariant spaces. A characterization for the univariate shift-invariant spaces of tempered distributions is given. In Lp case, an inclusive relation in terms of Fourier transform is established. 相似文献