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arXiv · 2506.20390

Endpoint estimates for the fractal circular maximal function and related local smoothing

Sanghyuk Lee·Luz Roncal·Feng Zhang·Shuijiang Zhao
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Abstract

Sharp $L^p$--$L^q$ estimates for the spherical maximal function over dilation sets of fractal dimensions, including the endpoint estimates, were recently proved by Anderson--Hughes--Roos--Seeger. More intricate $L^p$--$L^q$ estimates for the fractal circular maximal function were later established in the sharp range by Roos--Seeger, but the endpoint estimates have been left open, particularly when the fractal dimension of the dilation set lies in $[1/2, 1)$. In this work, we prove these missing endpoint estimates for the circular maximal function. We also study the closely related $L^p$--$L^q$ local smoothing estimates for the wave operator over fractal dilation sets, which were recently investigated by Beltran--Roos--Rutar--Seeger and Wheeler. Making use of a bilinear approach, we also extend the range of $p,q$, for which the optimal estimate holds.

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Sanghyuk Lee, Luz Roncal, Feng Zhang, Shuijiang Zhao. 2025-06-25. Endpoint estimates for the fractal circular maximal function and related local smoothing. https://arxiv.org/abs/2506.20390

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