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arXiv · 1609.08225

The Haar system as a Schauder basis in spaces of Hardy-Sobolev type

Gustavo Garrigós·Andreas Seeger·Tino Ullrich
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Abstract

We show that, for suitable enumerations, the multivariate Haar system is a Schauder basis in the classical Sobolev spaces on $\mathbb R^d$ with integrability $1<p<\infty$ and smoothness $1/p-1<s<1/p$. This complements earlier work by the last two authors on the unconditionality of the Haar system and implies that it is a {conditional} Schauder basis for a nonempty open subset of the $(1/p,s)$-diagram. The results extend to (quasi-)Banach spaces of Hardy-Sobolev and Triebel-Lizorkin type in the range of parameters $\frac{d}{d+1}<p<\infty$ and $\max\{d(1/p-1),1/p-1\}<s<\min\{1,1/p\}$, which is optimal except perhaps at the end-points.

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Gustavo Garrigós, Andreas Seeger, Tino Ullrich. 2016-09-27. The Haar system as a Schauder basis in spaces of Hardy-Sobolev type. https://arxiv.org/abs/1609.08225

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