On Bloom type estimates for iterated commutators of fractional integrals

TL;DR

This paper establishes quantitative Bloom type estimates for iterated commutators of fractional integrals, introduces new sparse domination techniques, and extends previous results to include sharpness and characterizations of BMO space.

Contribution

It provides new proofs and extensions of Bloom type estimates for iterated commutators, utilizing novel sparse domination methods and characterizing BMO space.

Findings

Established quantitative Bloom type estimates for iterated commutators

Introduced a new sparse domination technique for these estimates

Extended the necessity and sharpness results to the iterated case

Abstract

In this paper we provide quantitative Bloom type estimates for iterated commutators of fractional integrals improving and extending results from a work of Holmes, Rahm and Spencer. We give new proofs for those inequalities relying upon a new sparse domination that we provide as well in this paper and also in techniques developed in a recent paper due to Lerner, Ombrosi and the third author. We extend as well the necessity established in the work of Holmes, Rahm and Spencer to iterated commutators providing a new proof. As a consequence of the preceding results we recover the one weight estimates in works of Cruz-Uribe and Moen and B\'enyi, Martell, Moen, Stachura, Torres and establish the sharpness in the iterated case. Our result provides as well a new characterization of the BMO space.