Results 1 to 10 of about 694 (64)
REMARKS ON EMBEDDABLE SEMIGROUPS IN GROUPS AND A GENERALIZATION OF SOME CUTHBERT'S RESULTS
International Journal of Mathematics and Mathematical Sciences, Volume 2003, Issue 22, Page 1421-1431, 2003., 2003 Let (U(t))t≥0 be a C0-semigroup of bounded linear operators on a Banach space X. In this paper, we establish that if, for some t0 > 0, U(t0) is a Fredholm (resp., semiFredholm) operator, then (U(t))t≥0 is a Fredholm (resp., semi-Fredholm) semigroup ...
K. Latrach, Abdelkader Dehici
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Closedness of ranges of unbounded upper triangular operator matrices
Operators and Matrices, 2021 This paper deals with the closed range property of operator matrices. The necessary and sufficient condition is given for an unbounded upper triangular partial operator matrix to have a closed range completion.
Y. Qi, J. Huang, Alatancang Chen
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Global Perturbation of Nonlinear Eigenvalues
Advanced Nonlinear Studies, 2021 This paper generalizes the classical theory of perturbation of eigenvalues up to cover the most general setting where the operator surface 𝔏:[a,b]×[c,d]→Φ0(U,V){\mathfrak{L}:[a,b]\times[c,d]\to\Phi_{0}(U,V)}, (λ,μ)↦𝔏(λ,μ){(\lambda,\mu)\mapsto\mathfrak ...
López-Gómez Julián +1 more
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Generalized lower characteristic involving measures of non-strict singularity
Topological Algebra and its Applications, 2023 This work establishes a connection between the class of generalized lower characteristic operators and [⋅]a{\left[\cdot ]}_{a} acting on a Banach space involving measures of non-strict singularity.
Baraket Sami +2 more
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On (m, P)-expansive operators: products, perturbation by nilpotents, Drazin invertibility
Concrete Operators, 2021 A generalisation of m-expansive Hilbert space operators T ∈ B(ℋ) [18, 20] to Banach space operators T ∈ B(𝒳) is obtained by defining that a pair of operators A, B ∈ B(𝒳) is (m, P)-expansive for some operator P ∈ B(𝒳) if Δ A,Bm(P)= (I-LARB)m(P)=∑j=0m(-1)j(
Duggal B.P.
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Structure of n-quasi left m-invertible and related classes of operators
Demonstratio Mathematica, 2020 Given Hilbert space operators T,S∈B(ℋ)T,S\in B( {\mathcal H} ), let Δ\text{Δ} and δ∈B(B(ℋ))\delta \in B(B( {\mathcal H} )) denote the elementary operators ΔT,S(X)=(LTRS−I)(X)=TXS−X{\text{Δ}}_{T,S}(X)=({L}_{T}{R}_{S}-I)(X)=TXS-X and δT,S(X)=(
Duggal Bhagwati Prashad, Kim In Hyun
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A Trace Formula for the Dirac Operator [PDF]
, 2004 The theory of the spectral shift function is extended to the case where only the difference of some powers of the resolvents of self‐adjoint operators belongs to the trace class. As an example, a pair of Dirac operators is considered.
D. Yafaev
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PT Symmetric Schr\"odinger Operators: Reality of the Perturbed Eigenvalues [PDF]
, 2010 We prove the reality of the perturbed eigenvalues of some PT symmetric Hamiltonians of physical interest by means of stability methods. In particular we study 2-dimensional generalized harmonic oscillators with polynomial perturbation and the one ...
Caliceti, Emanuela +2 more
core +5 more sources
Perturbation of eigenvalues of matrix pencils and optimal assignment problem [PDF]
, 2004 We consider a matrix pencil whose coefficients depend on a positive parameter $\epsilon$, and have asymptotic equivalents of the form $a\epsilon^A$ when $\epsilon$ goes to zero, where the leading coefficient $a$ is complex, and the leading exponent $A ...
Baccelli +13 more
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Spectral perturbation bounds for selfadjoint operators I [PDF]
, 2007 We give general spectral and eigenvalue perturbation bounds for a selfadjoint operator perturbed in the sense of the pseudo-Friedrichs extension. We also give several generalisations of the aforementioned extension.
K. Veselic
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