Results 11 to 20 of about 99,725 (136)
A criterion for Hill operators to be spectral operators of scalar type [PDF]
Journal d'Analyse Mathématique, 2009 We derive necessary and sufficient conditions for a Hill operator (i.e., a one-dimensional periodic Schr dinger operator) $H=-d^2/dx^2+V$ to be a spectral operator of scalar type. The conditions show the remarkable fact that the property of a Hill operator being a spectral operator is independent of smoothness (or even analyticity) properties of the ...
Gesztesy, Fritz, Trachenko, Vadim
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Algebras of unbounded scalar-type spectral operators [PDF]
Pacific Journal of Mathematics, 1987 The main result of the paper is as follows. Let P:\(\Sigma\to L(X)\) be a closed spectral measure on the quasicomplete locally convex space X and T a densely defined linear operator on X with domain invariant under each operator of the form \(\int_{\Omega}fdP\), where f is a complex bounded \(\Sigma\)-measurable function.
Dodds, P.G. (author) +1 more
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Analysis of non scalar control problems for parabolic systems by the block moment method
Comptes Rendus. Mathématique, 2023 This article deals with abstract linear time invariant controlled systems of parabolic type. In [9], with A. Benabdallah, we introduced the block moment method for scalar control operators.
Boyer, Franck, Morancey, Morgan
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On the characterization of scalar type spectral operators [PDF]
Studia Mathematica, 2008 The paper is concerned with conditions guaranteeing that a bounded operator in a reflexive Banach space is a scalar type spectral operator. The cases where the spectrum of the operator lies on the real axis and on the unit circle are studied separately.
P. A. Cojuhari, A. M. Gomilko
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The mixed Yamabe problem for harmonic foliations [PDF]
, 2015 The mixed scalar curvature of a foliated Riemannian manifold, i.e., an averaged mixed sectional curvature, has been considered by several geometers. We explore the Yamabe type problem: to prescribe the constant mixed scalar curvature for a foliation by a
Rovenski, Vladimir, Zelenko, Leonid
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On the Non-Hypercyclicity of Normal Operators, Their Exponentials, and Symmetric Operators
Mathematics, 2019 We give a simple, straightforward proof of the non-hypercyclicity of an arbitrary (bounded or not) normal operator A in a complex Hilbert space as well as of the collection e t A t ≥ 0 of its exponentials, which, under a certain ...
Marat V. Markin, Edward S. Sichel
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Properties which normal operators share with normal derivations and related operators [PDF]
, 1975 Let $S$ and $T$ be (bounded) scalar operators on a Banach space $\scr X$ and let $C(T,S)$ be the map on $\scr B(\scr X)$, the bounded linear operators on $\scr X$, defined by $C(T,S)(X)=TX-XS$ for $X$ in $\scr B(\scr X)$.
Ciprian Poia, Joel Anderson, Let S
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OPERATOR METHOD IN THE SCALAR WAVE DIFFRACTION BY AXIALLY-SYMMETRIC DISCONTINUITIES IN THE SCREEN
Radio Physics and Radio Astronomy, 2018 Purpose: The scalar wave diffraction by the annular slot in an infinitely thin screen is considered in case of Dirichlet and Neumann boundary conditions. Diffraction problem by a flat ring is also considered as a dual one.
M. E. Kaliberda +2 more
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Spinning AdS Loop Diagrams: Two Point Functions [PDF]
, 2018 We develop a systematic approach to evaluating AdS loop amplitudes based on the spectral (or "split") representation of bulk-to-bulk propagators, which re-expresses loop diagrams in terms of spectral integrals and higher-point tree diagrams. In this work
Giombi, Simone +2 more
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A Dark Sector Extension of the Almost-Commutative Standard Model [PDF]
, 2013 We consider an extension of the Standard Model within the frame work of Noncommutative Geometry. The model is based on an older model [St09] which extends the Standard Model by new fermions, a new U(1)-gauge group and, crucially, a new scalar field which
Stephan, Christoph A.
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