scholarly journals On quasi-affinity and reducing subspaces of multiplication operator on a certain closed subspace

2020 ◽  
Vol 44 (5) ◽  
pp. 1534-1543
Author(s):  
Yucheng LI ◽  
Lina SONG ◽  
Wenhua LAN
Keyword(s):  
Closed Subspace ◽  
Multiplication Operator ◽  
Reducing Subspaces

scholarly journals Reducing subspaces for multiplication operators on the Dirichlet space through local inverses and Riemann surfaces

2017 ◽  
Vol 4 (1) ◽  
pp. 84-119 ◽  
Author(s):  
Caixing Gu ◽  
Shuaibing Luo ◽  
Jie Xiao
Keyword(s):  
Bergman Space ◽  
Blaschke Product ◽  
Riemann Surfaces ◽  
Dirichlet Space ◽  
Multiplication Operator ◽  
Multiplication Operators ◽  
Finite Blaschke Product ◽  
Full Characterization ◽  
Reducing Subspaces

AbstractThis paper gives a full characterization of the reducing subspaces for the multiplication operator Mϕ on the Dirichlet space with symbol of finite Blaschke product ϕ of order 5I 6I 7. The reducing subspaces of Mϕ on the Dirichlet space and Bergman space are related. Our strategy is to use local inverses and Riemann surfaces to study the reducing subspaces of Mϕ on the Bergman space. By this means, we determine the reducing subspaces of Mϕ on the Dirichlet space and answer some questions of Douglas-Putinar-Wang in [6].

scholarly journals On Similarity and Reducing Subspaces of the n-Shift plus Certain Weighted Volterra Operator

2017 ◽  
Vol 2017 ◽  
pp. 1-8
Author(s):  
Yucheng Li ◽  
Hao Chen ◽  
Wenhua Lan
Keyword(s):  
Hilbert Space ◽  
Bergman Space ◽  
Volterra Operator ◽  
Multiplication Operator ◽  
Degree Polynomial ◽  
Reducing Subspaces

Let g(z) be an n-degree polynomial (n≥2). Inspired by Sarason’s result, we introduce the operator T1 defined by the multiplication operator Mg plus the weighted Volterra operator Vg on the Bergman space. We show that the operator T1 is similar to Mg on some Hilbert space Sg2(D). Then for g(z)=zn, by using matrix manipulations, the reducing subspaces of the corresponding operator T2 on the Bergman space are characterized.

scholarly journals Classification of Reducing Subspaces of a Class of Multiplication Operators on the Bergman Space via the Hardy Space of the Bidisk

2010 ◽  
Vol 62 (2) ◽  
pp. 415-438 ◽  
Author(s):  
Shunhua Sun ◽  
Dechao Zheng ◽  
Changyong Zhong
Keyword(s):  
Hardy Space ◽  
Unit Disk ◽  
Bergman Space ◽  
Blaschke Product ◽  
Multiplication Operator ◽  
Multiplication Operators ◽  
Reducing Subspaces

AbstractIn this paper we obtain a complete description of nontrivial minimal reducing subspaces of the multiplication operator by a Blaschke product with four zeros on the Bergman space of the unit disk via the Hardy space of the bidisk.

Reducing subspaces for the product of a forward and a backward operator-weighted shifts

2021 ◽  
Vol 501 (2) ◽  
pp. 125206
Author(s):  
Xu Tang ◽  
Caixing Gu ◽  
Yufeng Lu ◽  
Yanyue Shi
Keyword(s):  
Weighted Shifts ◽  
Reducing Subspaces

scholarly journals In what spaces is every closed normal cone regular?

1970 ◽  
Vol 17 (2) ◽  
pp. 121-125 ◽  
Author(s):  
C. W. McArthur
Keyword(s):  
Banach Space ◽  
Convex Space ◽  
Unconditional Basis ◽  
Normal Cone ◽  
Closed Subspace ◽  
Locally Convex Space ◽  
Regular Part ◽  
Fréchet Space ◽  
Sequential Completeness ◽  
Locally Convex

It is known (13, p. 92) that each closed normal cone in a weakly sequentially complete locally convex space is regular and fully regular. Part of the main theorem of this paper shows that a certain amount of weak sequential completeness is necessary in order that each closed normal cone be regular. Specifically, it is shown that each closed normal cone in a Fréchet space is regular if and only if each closed subspace with an unconditional basis is weakly sequentially complete. If E is a strongly separable conjugate of a Banach space it is shown that each closed normal cone in E is fully regular. If E is a Banach space with an unconditional basis it is shown that each closed normal cone in E is fully regular if and only if E is the conjugate of a Banach space.

scholarly journals On Spectral Properties of Compact Toeplitz Operators on Bergman Space with Logarithmically Decaying Symbol and Applications to Banded Matrices

2021 ◽  
Author(s):  
Mahamet Koïta ◽  
Stanislas Kupin ◽  
Sergey Naboko ◽  
Belco Touré
Keyword(s):  
Spectral Analysis ◽  
Continuous Function ◽  
Bergman Space ◽  
Orthogonal Projection ◽  
Spectral Properties ◽  
Toeplitz Operators ◽  
Closed Subspace ◽  
Jacobi Matrices ◽  
Banded Matrices ◽  
Eigen Values

Abstract Let $L^2({{\mathbb{D}}})$ be the space of measurable square-summable functions on the unit disk. Let $L^2_a({{\mathbb{D}}})$ be the Bergman space, that is, the (closed) subspace of analytic functions in $L^2({{\mathbb{D}}})$. $P_+$ stays for the orthogonal projection going from $L^2({{\mathbb{D}}})$ to $L^2_a({{\mathbb{D}}})$. For a function $\varphi \in L^\infty ({{\mathbb{D}}})$, the Toeplitz operator $T_\varphi : L^2_a({{\mathbb{D}}})\to L^2_a({{\mathbb{D}}})$ is defined as $$\begin{align*} & T_\varphi f=P_+\varphi f, \quad f\in L^2_a({{\mathbb{D}}}). \end{align*}$$The main result of this article are spectral asymptotics for singular (or eigen-) values of compact Toeplitz operators with logarithmically decaying symbols, that is, $$\begin{align*} & \varphi(z)=\varphi_1(e^{i\theta})\, (1+\log(1/(1-r)))^{-\gamma},\quad \gamma>0, \end{align*}$$where $z=re^{i\theta }$ and $\varphi _1$ is a continuous (or piece-wise continuous) function on the unit circle. The result is applied to the spectral analysis of banded (including Jacobi) matrices.

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