English

New estimates for convex layer numbers

Metric Geometry 2021-04-22 v4 Combinatorics

Abstract

Starting with a finite point set XRdX \subset \mathbf{R}^d, the peeling process repeatedly removes the set of the vertices of the convex hull of the current set. The number of peeling steps required to completely remove XX is called the layer number of XX, denoted by L(X)L(X). In the article, we study the layer number of evenly distributed families of point sets contained in BdB^d, the dd-dimensional unit ball. These sets consist of points in BdB^d whose minimal distance is asymptotically as large as possible. We show that for a set XX belonging to an evenly distributed family, L(X)Ω(X1/d)L(X) \geq \Omega(|X|^{1/d}) holds, with the bound being asymptotically sharp. On the other hand, building on earlier results, we prove that L(X)O(X2/d)L(X)\leq O(|X|^{2/d}) holds for d2d\geq 2, which improves greatly on the current upper bound of O(X(d+1)/2d)O(|X|^{(d+1)/2d}) for d3d \geq 3. Finally, we provide a recursive construction of evenly distributed families whose sets satisfy L(X)=Θ(X2/d1/(d2d1))L(X) = \Theta(|X|^{2/d - 1/(d 2^{d-1})}), showing that our upper bound is nearly tight.

Keywords

Cite

@article{arxiv.2006.03799,
  title  = {New estimates for convex layer numbers},
  author = {Gergely Ambrus and Peter Nielsen and Caledonia Wilson},
  journal= {arXiv preprint arXiv:2006.03799},
  year   = {2021}
}

Comments

Accepted for publication in Discrete Mathematics

R2 v1 2026-06-23T16:06:28.868Z