Results 61 to 70 of about 8,503 (184)
Riesz bases of exponentials on unbounded multi-tiles [PDF]
Proceedings of the American Mathematical Society, 2018 We prove the existence of Riesz bases of exponentials of L 2 ( Ω ) L^2(\Omega ) , provided that Ω ⊂ R d \Omega \subset \mathbb {R}^d is a measurable set of finite and positive measure, not ...
Cabrelli, Carlos +1 more
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Pseudo-Duals of Frames and Modular Riesz Bases in Hilbert $C^\ast$-Modules [PDF]
Sahand Communications in Mathematical AnalysisIn the present article, duals, approximate duals and pseudo-duals (generated by bounded and not necessarily adjointable operators) of a frame in a Hilbert $C^\ast$-module are characterized and some of their properties are obtained.
Morteza Mirzaee Azandaryani
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Degree theory for 4‐dimensional asymptotically conical gradient expanding solitons
Communications on Pure and Applied Mathematics, Volume 79, Issue 5, Page 1151-1298, May 2026.Abstract We develop a new degree theory for 4‐dimensional, asymptotically conical gradient expanding solitons. Our theory implies the existence of gradient expanding solitons that are asymptotic to any given cone over S3$S^3$ with non‐negative scalar curvature. We also obtain a similar existence result for cones whose link is diffeomorphic to S3/Γ$S^3/\
Richard H. Bamler, Eric Chen
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The Steklov spectrum of spherical cylinders
Mathematika, Volume 72, Issue 2, April 2026.Abstract The Steklov problem on a compact Lipschitz domain is to find harmonic functions on the interior whose outward normal derivative on the boundary is some multiple (eigenvalue) of their trace on the boundary. These eigenvalues form the Steklov spectrum of the domain.
Spencer Bullent
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Decompositions of g-Frames and Duals and Pseudoduals of g-Frames in Hilbert Spaces
Journal of Function Spaces, 2015 Firstly, we study the representation of g-frames in terms of linear combinations of simpler ones such as g-orthonormal bases, g-Riesz bases, and normalized tight g-frames.
Xunxiang Guo
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Exponential Riesz bases, discrepancy of irrational rotations and BMO
, 2011 We study the basis property of systems of exponentials with frequencies belonging to 'simple quasicrystals'. We show that a diophantine condition is necessary and sufficient for such a system to be a Riesz basis in L^2 on a finite union of intervals. For
Kozma, Gady, Lev, Nir
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Duality for Evolutionary Equations With Applications to Null Controllability
Mathematical Methods in the Applied Sciences, Volume 49, Issue 5, Page 4144-4166, 30 March 2026.ABSTRACT We study evolutionary equations in exponentially weighted L2$$ {\mathrm{L}}^2 $$‐spaces as introduced by Picard in 2009. First, for a given evolutionary equation, we explicitly describe the ν$$ \nu $$‐adjoint system, which turns out to describe a system backwards in time. We prove well‐posedness for the ν$$ \nu $$‐adjoint system. We then apply
Andreas Buchinger, Christian Seifert
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Indian Journal of Pure and Applied MathematicsWe start by introducing and studying the definition of a Riesz basis in a Krein space $(\mathcal{K},[.,.])$, along with a condition under which a Riesz basis becomes a Bessel sequence. The concept of biorthogonal sequence in Krein spaces is also introduced, providing an equivalent characterization of a Riesz basis.
Jahan, Shah, Johnson, P. Sam
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PERTURBATION OF WAVELET FRAMES AND RIESZ BASES I [PDF]
Communications of the Korean Mathematical Society, 2004 Summary: Suppose that \(\psi\in L^2(\mathbb{R})\) generates a wavelet frame (resp. Riesz basis) with bounds \(A\) and \(B\). If \(\phi\in L^2(\mathbb{R})\) satisfies \(|\widehat{\psi}(\xi)- \widehat{\phi}(\xi)| < \lambda \frac{|\xi|^\alpha } { ( 1 + | \xi | )^\gamma} \) for some positive constants \(\alpha , \gamma , \lambda\) such that \(1< 1+\alpha <
Lee, Jin, Ha, Young-Hwa
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Karpatsʹkì Matematičnì Publìkacìï, 2018 We study a problem with periodic boundary conditions for a $2n$-order differential equation whose coefficients are non-self-adjoint operators. It is established that the operator of the problem has two invariant subspaces generated by the involution ...
Ya.O. Baranetskij +3 more
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