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Local Spectral Multiplicity of Selfadjoint Couplings with General Interface Conditions
We consider selfadjoint operators obtained by pasting a finite number of boundary relations with one-dimensional boundary space. A typical example of...
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Multilevel local defect-correction method for the non-selfadjoint Steklov eigenvalue problems
In this paper, we design a multilevel local defect-correction method to solve the non-selfadjoint Steklov eigenvalue problems. Since the computation...
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Linear preservers of m-selfadjoint operators and high-order isometries
Let H be a complex infinite-dimensional Hilbert space. Given a positive integer m , a bounded linear operator T on H is called m -selfadjoint if
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Functional Models of Symmetric and Selfadjoint Operators
Let A be a closed simple symmetric operator with equal defect numbers acting in a Hilbert space, and let...
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On the Work by Serguei Naboko on the Similarity to Unitary and Selfadjoint Operators
We review Serguei Naboko’s criteria for similarity of an operator to unitary or selfadjoint one, their relation to his functional model, applications...
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About the Limit Spectra of Some Unbounded Selfadjoint Integral Operators
We establish sufficient conditions for the zero to belong to the limit spectra of some unbounded selfadjoint integral operator.
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Improved Approximations of Resolvents in Homogenization of Higher Order Operators. The Selfadjoint Case
For selfadjoint elliptic operators in divergence form with ε -periodic coefficients of even order 2 m ≥ 4 we approximate the resolvent in the energy...
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Norm Estimates for Selfadjoint Toeplitz Operators on the Fock Space
An estimate for the norm of selfadjoint Toeplitz operators with a radial, bounded and integrable symbol is obtained. This emphasizes the fact that...
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Operator Estimates for Planar Domains with Irregularly Curved Boundary. The Dirichlet and Neumann Conditions
We consider a general nonselfadjoint second order scalar operator in a planar domain such that one of the boundary components is obtained by an...
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First Order Selfadjoint Differential Operators with Involution
AbstractIn this paper, certain spectral properties related with the first order linear differential-operator expression with involution in the...
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Selfadjoint Operators Under General Boundary Conditions
Let \(({\mathcal M}, g)\) be a...
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Real Structure in Operator Spaces, Injective Envelopes and G-spaces
We present some more foundations for a theory of real structure in operator spaces and algebras, in particular concerning the real case of the theory...
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Resolvent of a Schrödinger Operator on a Model Graph with Small Loops
We consider a Schrödinger operator on a model graph with small loops assuming the violation of the typical nonresonance condition which guarantees...
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On positive operator-valued measures generated by a family of one-dimensional projectors
We study positive operator-valued measures generated by projections on one-dimensional subspaces. A special attention is paid to the case in which...
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Improvement of Menshov’s Theorem on Upper Estimate for the Norm of Maximal Operator
We study the problem of estimating the majorant of partial sums of a series with respect to an orthogonal system. D. E. Menshov established that the...
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The Livšic function of a homogeneous symmetric operator and the multiplication theorem
This paper presents a solution to the Jørgensen–Muhly problem for a homogeneous symmetric operator with deficiency indices (1, 1) that does not admit ...
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Spectral Shift Function and Eigenvalues of the Perturbed Operator
In the space of square integrable functions on the positive semi-axis, two positive self-adjoint operators generated by a one-dimensional free...