共查询到20条相似文献,搜索用时 15 毫秒
1.
利用算子分块方法研究了具有一般定义域的形式Hamilton算子的可逆性和可逆补,还进一步给出了无穷维Hamilton算子的相关结论. 相似文献
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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. 相似文献
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Donald Sarason 《Integral Equations and Operator Theory》2008,61(2):281-298
This partly expository article develops the basic theory of unbounded Toeplitz operators on the Hardy space H
2, with emphasis on operators whose symbols are not square integrable. Unbounded truncated Toeplitz operators on coinvariant
subspaces of H
2 are also studied.
In memory of Paul R. Halmos 相似文献
6.
Dr. Mohammed Hichem Mortad 《Integral Equations and Operator Theory》2009,64(3):399-408
We give a spectral analysis of some unbounded normal product HK of two self-adjoint operators H and K (which appeared in [7]) and we say why it is not self-adjoint even if the spectrum of one of the operators is sufficiently
“asymmetric”. Then, we investigate the self-adjointness of KH (given it is normal) for arbitrary self-adjoint H and K by giving a counterexample and some positive results and hence finishing off with the whole question of normal products of
self-adjoint operators (appearing in [1, 7, 12]).
The author was supported in part by CNEPRU: B01820070020 (Ministry of Higher Education, Algeria). 相似文献
7.
W. Timmermann 《Mathematische Nachrichten》1979,91(1):347-355
The closure of the set of finite dimensional operators of ??+?? with respect to different topologies is considered. The obtained ideals have many properties similar to those of the ideal of completely continuous operators on HILBERT space. For example, under some appropriate assumptions all continuous functionals are normal, irreducible representations are equivalent to the identical representation and so on. 相似文献
8.
Zenon Jan Jabłoński Il Bong Jung Jan Stochel 《Integral Equations and Operator Theory》2014,79(1):135-149
Various characterizations of unbounded closed densely defined operators commuting with the spectral measures of their moduli are established. In particular, Kaufman’s definition of an unbounded quasinormal operator is shown to coincide with that given by the third-named author and Szafraniec. Examples demonstrating the sharpness of results are constructed. 相似文献
9.
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. 相似文献
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Sherwin Kouchekian 《Integral Equations and Operator Theory》2003,45(3):319-342
The unbounded Bergman operator, the operator of multiplication
by on an unbounded open subset of the plane, is considered. We give a complete
answer regarding the density problem of unbounded Bergman operators
in terms of its equivalence to the problem of bounded point evaluations for the
Bergman spaces. Using this equivalence and the notion of Wiener capacity, we
obtain simple geometric conditions that classify almost those open subsets of
the plane for which the corresponding Bergman operators are densely defined.
With the aid of an analytic approach, we are also able to give condition for a
large collection of open subsets of the plane for which all the positive integer
powers of the corresponding Bergman operators are densely defined.
Submitted: December 14, 2001? Revised: January 14, 2001. 相似文献
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D. R. Yafaev 《Integral Equations and Operator Theory》2016,84(2):289-300
This note presents a matricial generalization of the concept of rigid functions in the Hardy space H1, and a spectral characterization of complete non-determinacy for multivariate stationary processes. 相似文献
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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
. 相似文献
16.
W. Timmermann 《Mathematische Nachrichten》1979,92(1):99-110
A general procedure is given to get ideals in algebras of unbounded operators starting with ideals in ??(??). Algebraical and topological properties of ideals obtained in this manner from the well-known symmetrically-normed ideals S?(??) are described. 相似文献
17.
Vladimir V. Kisil Enrique Ramírez de Arellano 《Mathematical Methods in the Applied Sciences》1997,20(9):745-757
We extend the recently developed Riesz–Clifford monogenic functional calculus (based on Clifford analysis) for a set of unbounded non-commuting operators. Connections with quantum mechanics are discussed. © 1997 by B. G. Teubner Stuttgart–John Wiley & Sons Ltd. 相似文献
18.
In this paper, the authors investigate the spectral inclusion properties of the quadratic numerical range for unbounded Hamiltonian operators. Moreover, some examples are presented to illustrate the main results. 相似文献
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Daoxing Xia 《Integral Equations and Operator Theory》2006,55(3):439-452
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
相似文献