关于算子组Taylor谱的定义

给出了关于算子组Taylor谱的另一种定义及ε-联合伪谱的定义,并讨论了它的一些性质以及关于交叉交换算子组在这几种定义下的一些结果.     

联合半亚正常算子组的Taylor联合谱

本文定义了非重交换的联合半亚正常算子组,证明了谱分割定理和谱投影定理,提示了半亚正常算子组的 Taylor 联合谱与它们的记号算子组的 Taylor 联合谱之间的关系.     

投影算子组的联合谱

本文研究Hilbert空间H上投影算子组的联合谱.首先通过计算给出正则投影对的联合谱,进而给出一般的投影算子对的联合谱.本文还对两个投影算子的和与差的可逆性给出一些等价刻画.特别地,当P和Q为正则投影对时,本文通过计算算子组[I,P,Q]的联合谱来给出σ(P+Q)和σ(P-Q)的具体刻画.反过来,本文证明两类具有特定形...     

拟相似算子近似点谱的连通分支

讨论了Banach空间X上两个算子T，S拟相似时，近似点谱σα(T)的每一个连通分支与σα（S）以及σs(S)的相交关系，证明了σα(T)的每一个连通分支与σs(S)的交非空，并且给出了σα（T）的连通分支与σα（S）交非空的充要条件。     

算子的算子点谱的判定

本文讨论了算子Ａ∈Ｂ（Ｈ）_Ｎ为算子Ｔ∈Ｂ（Ｈ）的算子点谱的判定条件,特别得到：当Ｔ为亚正常算子时,Ａ为Ｔ的算子点谱的判定条件,另外还得到ｋｅｒτ^ｎ_Ｔ,Ａ＝ｋｅｒτ_Ｔ,Ａ成立的充分条件     

一类无穷维Hamilton算子的谱

研究了一类无穷维Hamilton算子的近似点谱及本质谱.进而通过无穷维Hamilton算子内部元素的乘积的谱对整体谱进行了刻画,最后证明了结论的正确性.     

算子的算子点谱的判定

本文讨论了算子A∈B(H)     

关于2n-算子组(LA,RB)的Taylor谱

设A=(A_1,……,A_n)与B=(B₁,……,B_n)为Hilbert空间H上的交换算子,L_A=(LA₁),……,LA_n))当R_B=(R(B₁,……,RB_n)分别为对应的B(H)中的左乘和右乘算子组。本文的主要结果是它们的Taylor谱有 Sp(L_A,R_B)=Sp(A)×Sp(B),
Sp_e(L_A,R_B)=Sp_e(A)×Sp(B)USp(A)×SP_e(B), 而且当A,B为Fredholm时,成立ind(L_A,R_B)=ind(A)·ind(B*)。我们用解算子方程的方法来证明上述命题,而且对Banach空间时,也作了一些讨论。     

拟绝对-*-κ-仿正规算子的谱性质

引入了拟绝对-*-k-仿正规算子,获得了拟绝对-*-k-仿正规算子的一个充要条件.并证明了拟绝对-*-k-仿正规算子在0≤k≤1上是有限上升的,作为此性质的应用,证明了若T是拟绝对-*-k-仿正规算子,其中0≤k≤1,则Weyl谱和本质近似点谱的谱映射定理成立.最后证明了若T是拟绝对-*-k-仿正规算子,其中0≤k≤1,则σ_(ja)(T)\{0}=σ_a(T)\{0}.     

k-拟-*-A算子的谱性质及其应用

主要给出k-拟-*-A算子的谱性质及其应用,若T是k-拟-*-A算子且N(T)■N(T~*),则Weyl谱的谱映射定理及本质近似点谱的谱映射定理成立;若T是k-拟-*-A算子,N(T)■N(T~*)且S～T,则a-Browder's定理对f(S)成立,其中f∈H(σ(S)).     

Right Spectrum and Trace Formula of Subnormal Tuples of Operators of Finite Type

This paper studies pure subnormal k-tuples of operators with finite rank of self-commutators. It determines the substantial part of the conjugate of the joint point spectrum of which is the union of domains in Riemann surfaces in some algebraic varieties in The concrete form of the principal current [4] related to is also determined. Besides, some operator identities are found for      

On Subnormality and Formal Subnormality for Tuples of Unbounded Operators

We introduce the notion of (joint) formal normality for a collection of unbounded linear operators on a separable Hilbert space H which is, in some sense, a natural generalization of the notion of formal normality for a single operator. We give some relations between this new notion and (joint) subnormality and hyponormality. We adapt, in particular, a proof of Stochel and Szafraniec to give necessary and sufficient conditions for a tupleof unbounded operators with invariant domain to be (jointly) subnormal.     

Absolute Equivalence and Dirac Operators of Commuting Tuples of Operators

In this paper we define an equivalence relation of operators on Hilbert spaces which we call absolute equivalence. Two operators are called absolutely equivalent if both the absolute value of the operators and their adjoints are unitarily equivalent. We then use the properties of this equivalence relation to study the Koszul complex of a commuting tuple of operators through the Dirac operator of the tuple.     

On the Spectrum of Invertible Semi-hyponormal Operators

It is known that for a semi-hyponormal operator, the spectrum of the operator is equal to the union of the spectra of the general polar symbols of the operator. The original proof of this theorem involves the so-called singular integral model. The purpose of this paper is to give a different proof of the same theorem for the case of invertible semi-hyponormal operators without using the singular integral model.      

On the Spectrum of the Product of Closed Operators

In this note we study the connection between the spectra of the products AB and BA of unbounded closed operators A and B acting in Banach spaces. Under the condition that the resolvent sets of these products are not empty we show that the spectra of AB and BA coincide away from zero and prove the commutation relation 𝕀 . Further, we prove statements concerning the relationship between the spectra of the operator AB and the block operator matrix .     

m-Isometric Commuting Tuples of Operators on a Hilbert Space

We consider a generalization of isometric Hilbert space operators to the multivariable setting. We study some of the basic properties of these tuples of commuting operators and we explore several examples. In particular, we show that the d-shift, which is important in the dilation theory of d-contractions (or row contractions), is a d-isometry. As an application of our techniques we prove a theorem about cyclic vectors in certain spaces of analytic functions that are properly contained in the Hardy space of the unit ball of .     

On the Spectrum of Frobenius–Perron Operators

We prove more results on the spectrum of the Frobenius–Perron operator P: L¹ → L¹ associated with a nonsingular transformation S: X → X on a σ-finite measure space (X, Σ, μ).     

On the Isolated Points of the Spectrum of Paranormal Operators

For paranormal operator T on a separable complex Hilbert space we show that (1) Weyl’s theorem holds for T, i.e., σ(T) \ w(T) = π₀₀(T) and (2) every Riesz idempotent E with respect to a non-zero isolated point λ of σ(T) is self-adjoint (i.e., it is an orthogonal projection) and satisfies that ranE = ker(T − λ) = ker(T − λ)^*.