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We use the Bellman function method to give an elementary proof of a sharp weighted estimate for the Haar shifts, which is linear in the $A_2$ norm of the weight and in the complexity of the shift. Together with the representation of a…

Classical Analysis and ODEs · Mathematics 2011-05-12 Sergei Treil

We investigate the weighted bounds for multilinear maximal functions and Calder\'on-Zygmund operators from $L^{p_1}(w_1)\times...\times L^{p_m}(w_m)$ to $L^{p}(v_{\vec{w}})$, where $1<p_1,...,p_m<\infty$ with $1/{p_1}+...+1/{p_m}=1/p$ and…

Classical Analysis and ODEs · Mathematics 2017-08-01 Kangwei Li , Kabe Moen , Wenchang Sun

Shifted variants of (dyadic) Hardy-Littlewood maximal function and Stein's square function have played a significant role in the study of many important operators such as Calderon commutators, (bilinear) Hilbert transforms, multilinear…

Classical Analysis and ODEs · Mathematics 2024-02-01 Bae Jun Park

In this paper, we consider the boundedness properties of multilinear $\theta$-type Calder\'on--Zygmund operators $T_\theta$ recently introduced in the literature. First, we prove strong type and weak type estimates for multilinear…

Classical Analysis and ODEs · Mathematics 2023-02-14 Xia Han , Hua Wang

It is shown that multilinear Calder\'on-Zygmund operators are bounded on products of Hardy spaces.

Functional Analysis · Mathematics 2007-05-23 Loukas Grafakos , Nigel Kalton

We obtain weighted mixed inequalities for operators associated to a critical radius function. We consider Schr\"odinger Calder\'on-Zygmund operators of $(s,\delta)$ type, for $1<s\leq \infty$ and $0<\delta \leq 1$. We also give estimates of…

Analysis of PDEs · Mathematics 2022-08-10 Fabio Berra , Gladis Pradolini , Pablo Quijano

In this paper, starting with a relatively simple observation that the variational estimates of the commutators of the standard Calder\'on-Zygmund operators with the BMO functions can be deduced from the weighted variational estimates of the…

Classical Analysis and ODEs · Mathematics 2017-09-12 Yanping Chen , Yong Ding , Guixiang Hong , Honghai Liu

We prove quadratic estimates for complex perturbations of Dirac-type operators, and thereby show that such operators have a bounded functional calculus. As an application we show that spectral projections of the Hodge--Dirac operator on…

Spectral Theory · Mathematics 2009-11-10 Andreas Axelsson , Stephen Keith , Alan McIntosh

In this paper, we develop a comprehensive weighted theory for a class of Banach-valued multilinear bounded oscillation operators on measure spaces, which merges multilinear Calder\'{o}n-Zygmund operators with a quantity of operators beyond…

Classical Analysis and ODEs · Mathematics 2024-03-26 Mingming Cao , Gonzalo Ibañez-Firnkorn , Israel P. Rivera-Ríos , Qingying Xue , Kôzô Yabuta

We give a new proof of the sharp weighted $L^2$ inequality ||T||_{L^2(w)} \leq c [w]_{A_2} where $T$ is the Hilbert transform, a Riesz transform, the Beurling-Ahlfors operator or any operator that can be approximated by Haar shift…

Classical Analysis and ODEs · Mathematics 2014-05-14 David Cruz-Uribe , Jose Maria Martell , Carlos Perez

We consider local weak solutions of the Poisson equation for the p--Laplace operator. We prove a higher differentiability result, under an essentially sharp condition on the right-hand side. The result comes with a local scaling invariant a…

Analysis of PDEs · Mathematics 2016-07-25 Lorenzo Brasco , Filippo Santambrogio

In this paper we study weighted estimates for the multi-frequency $\omega-$Calder\'{o}n-Zygmund operators $T$ associated with the frequency set $\Theta=\{\xi_1,\xi_2,\dots,\xi_N\}$ and modulus of continuity $\omega$ satisfying the usual…

Classical Analysis and ODEs · Mathematics 2023-08-15 Saurabh Shrivastava , K. S. Senthil Raani

We prove necessary and sufficient conditions for a Calder\'on-Zygmund operator to be compact at the endpoint from $L^{1}(\mathbb R^{d})$ into $L^{1,\infty}(\mathbb R^{d})$.

Classical Analysis and ODEs · Mathematics 2015-12-18 Jan-Fredrik Olsen , Paco Villarroya

In this paper we establish mixed weak inequalities of Fefferman-Stein type for Calder\'on-Zygmund operators and their commutators, improving some previous results known in the literature. The main estimates also generalize the classical…

Classical Analysis and ODEs · Mathematics 2025-11-20 Rocío Ayala , Fabio Berra , Gladis Pradolini

We obtain a complete characterization of the weak-type $(1,1)$ for Haar shift operators in terms of generalized Haar systems adapted to a Borel measure $\mu$ in the operator-valued setting. The main technical tool in our method is a…

Classical Analysis and ODEs · Mathematics 2014-12-17 José M. Conde-Alonso , Luis Daniel López-Sánchez

We give a self-contained proof of the $A_2$ conjecture, which claims that the norm of any Calderon-Zygmund operator is bounded by the first degree of the $A_2$ norm of the weight. The original proof of this result by the first author relied…

Classical Analysis and ODEs · Mathematics 2010-12-09 Tuomas Hytönen , Carlos Pérez , Sergei Treil , Alexander Volberg

This note is devoted to the study of Hyt\"{o}nen's extrapolation theorem of compactness on weighted Lebesgue spaces. Two criteria of compactness of linear operators in the two-weight setting are obtained. As applications, we obtain…

Analysis of PDEs · Mathematics 2021-06-08 Shenyu Liu , Huoxiong Wu , Dongyong Yang

We prove the matrix $A_2$ conjecture for the dyadic square function, that is, a norm estimate of the matrix weighted square function, where the focus is on the sharp linear dependence on the matrix $A_2$ constant in the estimate. Moreover,…

Classical Analysis and ODEs · Mathematics 2019-04-02 Tuomas Hytönen , Stefanie Petermichl , Alexander Volberg

We demonstrate and develop dyadic-probabilistic methods in connection with non-homogeneous bilinear operators, namely singular integrals and square functions. We develop the full non-homogeneous theory of bilinear singular integrals using a…

Classical Analysis and ODEs · Mathematics 2018-10-19 Henri Martikainen , Emil Vuorinen

We present a framework based on modified dyadic shifts to prove multiple results of modern singular integral theory under mild kernel regularity. Using new optimized representation theorems we first revisit a result of Figiel concerning the…

Classical Analysis and ODEs · Mathematics 2020-09-28 Emil Airta , Henri Martikainen , Emil Vuorinen