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JOURNALS // Matematicheskii Sbornik // Archive

Mat. Sb., 2021 Volume 212, Number 6, Pages 73–108 (Mi sm9398)

This article is cited in 2 papers

Multivariate Haar systems in Besov function spaces

P. Oswald

Institute for Numerical Simulation, University of Bonn, Bonn, Germany

Abstract: We determine all cases for which the $d$-dimensional Haar wavelet system $H^d$ on the unit cube $I^d$ is a conditional or unconditional Schauder basis in the classical isotropic Besov function spaces ${B}_{p,q,1}^s(I^d)$, $0<p,q<\infty$, $0\le s < 1/p$, defined in terms of first-order $L_p$-moduli of smoothness. We obtain similar results for the tensor-product Haar system $\widetilde{H}^d$, and characterize the parameter range for which the dual of ${B}_{p,q,1}^s(I^d)$ is trivial for $0<p<1$.
Bibliography: 31 titles.

Keywords: Haar system, Besov spaces, Schauder bases in quasi-Banach spaces, unconditional convergence, piecewise-constant approximation.

UDC: 517.518.34+517.982.254

MSC: Primary 42C40, 46E35; Secondary 41A15, 41A63

Received: 28.02.2020 and 13.02.2021

DOI: 10.4213/sm9398


 English version:
Sbornik: Mathematics, 2021, 212:6, 810–842

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© Steklov Math. Inst. of RAS, 2026