Pinned distances and density theorems in $\mathbb R^d$
Classical Analysis and ODEs
2025-09-03 v1
Abstract
We study a pinned variant of Bourgain's theorem, concerning the occurrence of affine copies of -point patterns in . Focusing on the case , which corresponds to pinned distances, we show that the classical conclusion does not extend to the pinned setting: there exist sets of positive upper density in , , such that no single pinned point determines all sufficiently large distances. However, we establish a weaker quantitative result: for every point in such a set, the pinned distance set at has (one-dimensional) positive upper density. We also construct an example demonstrating the sharpness of this bound. These findings highlight a structural distinction between global and pinned configurations.
Cite
@article{arxiv.2509.01152,
title = {Pinned distances and density theorems in $\mathbb R^d$},
author = {Chenjian Wang},
journal= {arXiv preprint arXiv:2509.01152},
year = {2025}
}