共查询到20条相似文献,搜索用时 15 毫秒
1.
《Journal of Functional Analysis》2023,284(5):109801
In this paper we study the boundedness of composition operators on the weighted Bergman spaces and the Hardy space over the polydisc . Studying the volume of sublevel sets we show for which n the necessary conditions obtained by Bayart are sufficient. For arbitrary polydisc we prove the rank sufficiency theorem which, in particular, provides us with a simple criterion describing boundedness of composition operators on the spaces over the bidisc. Such a consistent characterization is obtained for the classical Bergman space over the tridisc. 相似文献
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We study multivariate approximation of periodic functions in the worst case setting with the error measured in the norm. We consider algorithms that use standard information consisting of function values or general linear information consisting of arbitrary continuous linear functionals. We investigate equivalences of various notions of algebraic and exponential tractability for and under the absolute or normalized error criterion, and show that the power of is the same as the one of for various notions of algebraic and exponential tractability. Our results can be applied to weighted Korobov spaces and Korobov spaces with exponential weights. This gives a special solution to Open Problem 145 as posed by Novak and Woźniakowski (2012) [40]. 相似文献
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Joachim Toft 《Applied and Computational Harmonic Analysis》2019,46(1):154-176
We extend Feichtinger's minimality property on the smallest non-trivial time-frequency shift invariant Banach space, to the quasi-Banach case. Analogous properties are deduced for certain matrix spaces.We use these results to prove that the pseudo-differential operator is a Schatten-q operator from to and r-nuclear operator from to when for suitable p, q and r in . 相似文献
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《Indagationes Mathematicae》2019,30(5):930-942
We extend the notions of -convexity and -concavity for Banach ideals of measurable functions following an asymptotic procedure. We prove a representation theorem for the spaces satisfying both properties as the one that works for the classical case: each almost -convex and almost -concave space is order isomorphic to an almost--space. The class of almost--spaces contains, in particular, direct sums of (infinitely many) -spaces with different norms, that are not in general -convex – nor -concave –. We also analyze in this context the extension of the Maurey–Rosenthal factorization theorem that works for -concave operators acting in -convex spaces. In this way we provide factorization results that allow to deal with more general factorization spaces than -spaces. 相似文献
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Bhargav Bhatt 《Journal of Pure and Applied Algebra》2019,223(5):1940-1945
Given a commutative ring A and a finitely generated ideal I, we prove that -torsion A-modules that are also I-adically complete (or merely derived I-complete) must have bounded -torsion, i.e., they are killed by for some . 相似文献
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For a closed symplectic manifold with compatible Riemannian metric g we study the Sobolev geometry of the group of all diffeomorphisms on M which preserve the symplectic structure. We show that, for sufficiently large s, the metric admits globally defined geodesics and the corresponding exponential map is a non-linear Fredholm map of index zero. Finally, we show that the metric carries conjugate points via some simple examples. 相似文献
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Cédric Arhancet 《Journal of Functional Analysis》2019,276(7):2279-2314
We prove that any weak* continuous semigroup of factorizable Markov maps acting on a von Neumann algebra M equipped with a normal faithful state can be dilated by a group of Markov ?-automorphisms analogous to the case of a single factorizable Markov operator, which is an optimal result. We also give a version of this result for strongly continuous semigroups of operators acting on noncommutative -spaces and examples of semigroups to which the results of this paper can be applied. Our results imply the boundedness of the McIntosh's functional calculus of the generators of these semigroups on the associated noncommutative -spaces generalising some previous work from Junge, Le Merdy and Xu. Finally, we also give concrete dilations for Poisson semigroups which are even new in the case of . 相似文献
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In this paper, we introduce the Fock space on and obtain an isomorphism between the Fock space on and Bose-Fock space. Based on this isomorphism, we obtain representations of some operators on the Bose-Fock space and answer a question in [2]. As a physical application, we study the Gibbs state. 相似文献
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《Journal of Functional Analysis》2023,284(6):109828
This paper is twofold. The first part aims to study the long-time asymptotic behavior of solutions to the heat equation on Riemannian symmetric spaces of noncompact type and of general rank. We show that any solution to the heat equation with bi-K-invariant initial data behaves asymptotically as the mass times the fundamental solution, and provide a counterexample in the non bi-K-invariant case. These answer problems recently raised by J.L. Vázquez. In the second part, we investigate the long-time asymptotic behavior of solutions to the heat equation associated with the so-called distinguished Laplacian on . Interestingly, we observe in this case phenomena which are similar to the Euclidean setting, namely asymptotic convergence with no bi-K-invariance condition and strong convergence. 相似文献
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In this paper, we construct new families of flag-transitive linear spaces with points and points on each line that admit a one-dimensional affine automorphism group. We achieve this by building a natural connection with permutation polynomials of of a particular form and following the scheme of Pauley and Bamberg in (2008) [14]. 相似文献
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Hai Q. Dinh Xiaoqiang Wang Hongwei Liu Songsak Sriboonchitta 《Discrete Mathematics》2019,342(11):3062-3078
Let be an odd prime, and be a nonzero element of the finite field . The -constacyclic codes of length over are classified as the ideals of quotient ring in terms of their generator polynomials. Based on these generator polynomials, the symbol-pair distances of all such -constacyclic codes of length are obtained in this paper. As an application, all MDS symbol-pair constacyclic codes of length over are established, which produce many new MDS symbol-pair codes with good parameters. 相似文献
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A new a priori estimate for solutions to Navier–Stokes equations is derived. Uniqueness and existence of these solutions in for all is proved in a class of solutions locally differentiable in time with values in , where is the Sobolev space. By the solution a solution to an integral equation is understood. No smallness restrictions on the data are imposed. 相似文献