UNBOUNDED COMPLEX SYMMETRIC TOEPLITZ OPERATORS

In this paper,we study unbounded complex symmetric Toeplitz operators on the Hardy space H²(D) and the Fock space g².The technique used to investigate the complex symmetry of unbounded Toeplitz operators is different from that used to investigate the complex symmetry of bounded Toeplitz operators.     

COMPLEX SYMMETRIC TOEPLITZ OPERATORS ON THE UNIT POLYDISK AND THE UNIT BALL

In this article, we study complex symmetric Toeplitz operators on the Bergman space and the pluriharmonic Bergman space in several variables. Surprisingly, the necessary and sufficient conditions for Toeplitz operators to be complex symmetric on these two spaces with certain conjugations are just the same. Also, some interesting symmetry properties of complex symmetric Toeplitz operators are obtained.     

Bergman空间上具有无界符号的迹类Toeplitz算子

本文研究了Bergman空间上具有无界符号的迹类Toeplitz算子的问题.利用构造的方法,获得了L2(Un,dA)中的函数φ,φ在Tn中每一点的任何邻域内都是无界的,并且使得Tφ是Bergman空间Lα2(Un,dA)上的迹类算子的结果.     

COMPLEX SYMMETRY OF TOEPLITZ OPERATORS OVER THE BIDISK

In this paper,we investigate the complex symmetric structure of Toeplitz operators T_φ on the Hardy space over the bidisk.We first characterize the weighted composition operators,W_u,v which are J-symmetric and unitary.As a consequence,we characterize conjugations of the form A_u,v.In addition,a class of conjugations of the form C_λ,a is introduced.We show that the class of conjugations C_λ,a coincides with the class of conjugations A_u,v     

多复变量Toeplitz算子的交换性

本文刻画了C~n中单位球和多圆盘Bergman空间上一些Toeplitz算子的换位。首先,对双圆盘Bergman空间,刻画了什么时候 Toeplitz算子T_f和T_g交换,这里 f=f1+,g=g1+,fi,gi∈H~∞(D~2)(i=1,2)。其次,如果表示由多复变量 Toeplitz算子生成的赋范闭子代数,证明了对每个正整数m,{T_z_1~m,…,T_z_n~m}′∩是所有解析Toeplitz算子的集合,这里z_i(i=1,…,n)是坐标函数。     

多复变量Toeplitz算子的交换性

本文刻画了Cn中单位球和多圆盘Bergman空间上一些Toeplitz算子的换位.首先,对双圆盘Bergman空间,刻画了什么时候Toeplitz算子Tf和Tg交换,这里f=f1+-f2,g=g1+-g2,fi,gi∈H∞(D2)(i=1,2).其次,如果R表示由多复变量Toeplitz算子生成的赋范闭子代数,证明了对每个正整数m,{Tzm,…,Tzmn}'∩R是所有解析Toeplitz算子的集合,这里zi(i=1,…,n)是坐标函数.     

TOEPLITZ OPERATORS ON HEISENBERG GROUP

Denote by Ω the Siegel domain in Cn, n 〉 1. In this paper, we study the essential spectra of Toeplitz operators defined on the Hardy space H2（а↓Ω）. In addition, the characteristic equation of analytic Toeplitz operators iааs obtained.     

TOEPLITZ OPERATORS AND ALGEBRAS ON DIRICHLET SPACES

The automorphism group of the Toeplitz C-algebra,J(C~1),generated by Toeplitz op-erators with C~1-symbols on Dirichlet space D is discussed;the K_0,X_1-groups and the firstcohomology group of J(C~1)are computed.In addition,the author provs that the spectraof Toeplitz operators with C~1-symbols are always connected,and discusses the algebraic prop-erties of Toeplitz operators.In particular,it is proved that there is no nontrivial selfadjointToeplitz operator on D and T_φ~*=T_φ if and only if T_φ is a scalar operator.     

有界多连通域的Schatten类Toeplitz算子

本文讨论了多连通域的Bergman空间上的以正测度为符号的Toeplitz算子.用符号测度的Berezin 变换和平均函数刻画了Toeplitz算子为Schatten类算子的充要条件.     

有界多连通域的Schatten类Toeplitz算子

本文讨论了多连通域的Bergman空间上的以正测度为符号的Toeplitz算子.用符号测度的Berezin变换和平均函数刻画了Toeplitz算子为Schatten类算子的充要条件.     

加权Dirichlet空间上具有无界符号的Toeplitz算子(英文)

本文研究了加权Dirichlet空间上一类Toeplitz性质的问题.利用构造单位圆盘D上一类无界函数的方法,获得了以它为符号的Toeplitz算子是紧的结果.同时也通过构造一类L2(?)上的函数,使得它们在单位圆周上每一点的任何一个邻域都无界的方法,获得了以这些函数为符号的Toeplitz算子是迹类算子的结果.     

FACTORIZATION OF UNBOUNDED THIN AND COTHIN OPERATORS

Abstract

Let X and Y be normed spaces and T: D(T) ? X → Y a linear operator. Following R.D. Neidingcr [N1] we recall the Davis, Figiel, Johnson, Pelczynski factorization of T corresponding to a parameter p (1 ≤ p ≤ ∞) and apply the corresponding factorization result in [N1] to unbounded thin operators. Properties equivalent to ubiquitous thinness arc derived. Defining an operator T to be cothin if its adjoint is thin, a dual factorization result for cothin operators is obtained, where for each 1 < p < ∞, the intermediate space in the factorization is cohereditarily l_p. This result is shown to hold more generally for the cases when T is either partially continuous or closable; in particular, such operators are strictly cosingular. A condition for a closable weakly compact operator to be strictly cosingular follows as a corollary.     

IDENTIFICATION OF EXTRAPOLATION SPACES FOR UNBOUNDED OPERATORS

Abstract

Abstract extrapolation spaces for strongly continuous semigroups of linear operators on Banach spaces have been constructed by various methods (see, e.g., [Am (1988)], [DaP-Gr (1984)], [Na (1983)], [Ne (1992)], [Wa (1986)]). Usually they appear as “artefacts” used in some intermediate step in order to solve the Cauchy problem on the original space. Only in a few cases (see the papers by the Dutch school on X ^⊙*, e.g., [Ne (1992)]), and in sharp contrast to the situation for interpolation spaces (see, e.g., [Gr (1969)], [DiB (1991)], [Lu (1985)], [Ac-Te (1987)]), the extrapolation spaces have been identified in a concrete way. It is our intention to fill this gap and subsequently to give an application of the extrapolation method to a perturbation problem.     

对称Toeplitz系统的快速W变换基预条件子

１．引言考虑下列Ｎ阶线性方程组其中T_N=(t_i,j)　是Ｎ×Ｎ阶实对称正定（ＳＰＤ）Ｔｏｅｐｌｉｔｚ矩阵,即０,１,…,Ｎ－１）且Ｔ_Ｎ的所有特征值为正数．Ｔｏｅｐｌｉｔｚ系统已广泛应用于数字信号处理,时间序列分析（参见［１］）以及微分方程的数值解（参见［２１］等领域．八十年代以前,考虑到Ｔｏｅｐｌｉｔｚ矩阵的特殊性,人们主要用Ｌｅｖｉｎｓｏｎ递推技术及其变形或者分而治之思想直接求解方程组（１．１）,计算复杂性为Ｏ（Ｎ~（２））或Ｏ（ＮｌｏｇＮ~（２））（参见［３］）;比Ｇａｕｓｓ法运算量级Ｏ（Ｎ~（３）…     

TOEPLITZ OPERATORS ASSOCIATED WITH SEMIFINITE VON NEUMANN ALGEBRA

Let H2(M) be a noncommutative Hardy space associated with semifinite von Neumann algebra M, we get the connection between numerical spectrum and the spectrum of Toeplitz operator Tt acting on H2(M), and the norm of Toeplitz operator Tt is equivalent to ||t|| when t is hyponormal operator in M.     

加权Bergman空间上的Toeplitz算子和Hankel算子

西方给出了Ｃ＾ｎ中单位球上的带权的Ｂｅｒｇｍａｎ空间上具一般符号的Ｔｏｅｐｌｉｔｚ算子和Ｈａｎｋｅｌ算子为紧的充要条件。     

Toeplitz算子Fredholm性质的局部化描述

利用Banach代数中的局部化定理描述Bergman空间上Toeplitz算子的Fredholm性质,证明了类似于Hardy空间上的一个局部化定理．讨论了L∞（D）的极大理想空间的一些性质．     

对称正定Toeplitz方程组的多级迭代求解

二级迭代法亦称内外迭代法. 多级迭代法由多个二级迭代嵌套而成.这些方法特别适合于并行计算,同时可以理解为古典迭代法的延伸或共轭梯度法的预处理子.本文讨论了对称正定Toeplitz线性方程组多级迭代法. 首先,基于Toeplitz矩阵的结构, 我们给出了多级块Jacobi分裂,然后证明了每一级分裂均为P-正则分裂, 并证明了当每一级内迭代次数均为偶数时,迭代法的收敛性. 最后通过数值实例验证了此方法的有效性.     

NOTE ON SOME CHARACTERISATIONS OF UNBOUNDED WEAKLY COMPACT OPERATORS

Abstract

Some well known properties of bounded weakly compact operators in Banach spaces are shown to be valid for arbitrary operators in normed spaces.     

HYPONORMALITY OF BLOCK TOEPLITZ OPERATORS ON THE WEIGHTED BERGMAN SPACES

In this paper we consider the block Toeplitz operators T_Φ on the weighted Bergman space A_α~2(D,C~n) and we give a necessary and sufficient condition for the hyponormality of block Toeplitz operators with symbol in the class of functions Φ=F+G* with matrix-valued polynomial functions F and G with degree 2.