Two-ends Furstenberg estimates in the plane
Hong Wang, Shukun Wu
TL;DR
This work addresses two-ends Furstenberg-type incidence bounds in the plane for Katz-Tao $(\delta,t)$-sets of lines, extending prior results to general $t\in[0,2]$. The authors develop a comprehensive framework combining shading, two-ends conditions, uniformization, branching functions, and multi-scale decomposition, and they integrate powerful Furstenberg-type results from recent literature to obtain a quantitative lower bound on the union of shadings. A key novelty is the appearance of the factor $\gamma_{Y,t^*}^{-1/2}$, which captures the non-uniform distribution of $Y(\ell)$ across scales and is necessary except in the symmetric case $t=1$. The results advance planar incidence geometry by enabling two-ends Furstenberg estimates for broad line families and illuminate the role of scale-sensitive distributional parameters in fractal incidence bounds.
Abstract
We prove two-ends Furstenberg estimates in the plane for a Katz-Tao $(δ,t)$-set of lines, for general $t\in[0,2]$.
