Results 1 to 10 of about 95 (87)
On One Method of Studying Spectral Properties of Non‐selfadjoint Operators
Abstract and Applied Analysis, Volume 2020, Issue 1, 2020., 2020 In this paper, we explore a certain class of Non‐selfadjoint operators acting on a complex separable Hilbert space. We consider a perturbation of a nonselfadjoint operator by an operator that is also nonselfadjoint. Our consideration is based on known spectral properties of the real component of a nonselfadjoint compact operator.
Maksim V. Kukushkin, Jose L. Gracia
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Investigating Predictors of Differential Trajectories of Suicidal Desire Across an Intensive Longitudinal Design. [PDF]
Suicide Life Threat BehavABSTRACT Objective To understand the evolution of suicide risk, repeated assessments of suicide‐related symptoms are necessary. Though previous studies have examined sample‐level effects, there is a dearth of research examining possible differential risk trajectories, including vulnerable subgroups, and how subgroup differences may produce distinct ...
Rogers ML, Robison M, Tran JH, Mitaj D.
europepmc +2 more sources
Norms on complex matrices induced by complete homogeneous symmetric polynomials
Bulletin of the London Mathematical Society, Volume 54, Issue 6, Page 2078-2100, December 2022., 2022 Abstract We introduce a remarkable new family of norms on the space of n×n$n \times n$ complex matrices. These norms arise from the combinatorial properties of symmetric functions, and their construction and validation involve probability theory, partition combinatorics, and trace polynomials in non‐commuting variables.
Konrad Aguilar +3 more
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Exterior products of operators and superoptimal analytic approximation
Transactions of the London Mathematical Society, Volume 8, Issue 1, Page 299-412, December 2021., 2021 Abstract We give a new algorithm for the construction of the unique superoptimal analytic approximant of a given continuous matrix‐valued function on the unit circle, using exterior powers of operators in preference to spectral or Wiener–Masani factorizations.
Dimitrios Chiotis +2 more
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Bilinear Localization Operators on Modulation Spaces
Journal of Function Spaces, Volume 2018, Issue 1, 2018., 2018 We introduce a class of bilinear localization operators and show how to interpret them as bilinear Weyl pseudodifferential operators. Such interpretation is well known in linear case whereas in bilinear case it has not been considered so far.
Nenad Teofanov, Kasso A. Okoudjou
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Functions of self‐adjoint operators in ideals of compact operators
Journal of the London Mathematical Society, Volume 95, Issue 1, Page 157-176, February 2017., 2017 Abstract For self‐adjoint operators A,B, a bounded operator J, and a function f:R→C, we obtain bounds in quasi‐normed ideals of compact operators for the difference f(A)J−Jf(B) in terms of the operator AJ−JB. The focus is on functions f that are smooth everywhere except for finitely many points. A typical example is the function f(t)=|t|γ with γ∈(0,1).
Alexander V. Sobolev
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Perturbations of Polynomials with Operator Coefficients
Journal of Complex Analysis, Volume 2013, Issue 1, 2013., 2013 We consider polynomials whose coefficients are operators belonging to the Schatten‐von Neumann ideals of compact operators in a Hilbert space. Bounds for the spectra of perturbed pencils are established. Applications to differential and difference equations are also discussed.
Michael Gil′, Janne Heittokangas
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The Calderón Reproducing Formula Associated with the Heisenberg Group Hd
Mathematical Problems in Engineering, Volume 2010, Issue 1, 2010., 2010 We establish the Calderón reproducing formula for functions in L2 on the Heisenberg group Hd. Also, we develop this formula in Lp(Hd) with 1 < p < ∞.
Jinsen Xiao, Jianxun He, Victoria Vampa
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Scattering theory for difference equations with operator coefficients
Journal of the London Mathematical Society, Volume 113, Issue 3, March 2026.Abstract We investigate a class of second‐order difference equations featuring operator‐valued coefficients with the aim of approaching problems of stationary scattering theory. We focus on various compact perturbations of the discrete Laplacian given in a Hilbert space of bi‐infinite square‐summable sequences with entries from a fixed Hilbert space ...
David Sher +3 more
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Maximal Regularity for Flexible Structural Systems in Lebesgue Spaces
Mathematical Problems in Engineering, Volume 2010, Issue 1, 2010., 2010 We study abstract equations of the form λu′′′(t) + u′′(t) = c2Au(t) + c2μAu′(t) + f(t), 0 < λ < μ which is motivated by the study of vibrations of flexible structures possessing internal material damping. We introduce the notion of (α; β; γ)‐regularized families, which is a particular case of (a; k)‐regularized families, and characterize maximal ...
Claudio Fernández +3 more
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