Sawyer's extrapolation conjecture for mixed weak-type maximal estimates

From papers

Let MM be the Hardy–Littlewood maximal operator on Rn\mathbb{R}^n, let uu be a weight in A1A_1, and let vv be a weight satisfying

M(fv)vL1,(v)cvfL1(v).\Big\|\frac{M(fv)}{v}\Big\|_{L^{1,\infty}(v)}\le c_v\|f\|_{L^1(v)}.

Sawyer's extrapolation conjecture. There is a finite constant cc, depending on the A1A_1 constant of uu and on cvc_v, such that

M(fv)vL1,(uv)cfL1(uv).\Big\|\frac{M(fv)}{v}\Big\|_{L^{1,\infty}(uv)}\le c\,\|f\|_{L^1(uv)}.

This conjecture proposes extrapolating a weak-type estimate for the weight vv to the mixed measure uvuv whenever uA1u\in A_1. The surrounding discussion gives positive and negative examples for related hypotheses, but the source does not state a resolution of this general assertion.

Progress summary

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Sources & referencesView supporting material

Primary source

Kangwei Li, Sheldy Ombrosi and Carlos Pérez, “Proof of an extension of E. Sawyer's conjecture about weighted mixed weak-type estimates”, arXiv:1703.01530 (2017).

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