English

Extending the centerpoint theorem to multiple points

Computational Geometry 2018-10-25 v1

Abstract

The centerpoint theorem is a well-known and widely used result in discrete geometry. It states that for any point set PP of nn points in Rd\mathbb{R}^d, there is a point cc, not necessarily from PP, such that each halfspace containing cc contains at least nd+1\frac{n}{d+1} points of PP. Such a point cc is called a centerpoint, and it can be viewed as a generalization of a median to higher dimensions. In other words, a centerpoint can be interpreted as a good representative for the point set PP. But what if we allow more than one representative? For example in one-dimensional data sets, often certain quantiles are chosen as representatives instead of the median. We present a possible extension of the concept of quantiles to higher dimensions. The idea is to find a set QQ of (few) points such that every halfspace that contains one point of QQ contains a large fraction of the points of PP and every halfspace that contains more of QQ contains an even larger fraction of PP. This setting is comparable to the well-studied concepts of weak ε\varepsilon-nets and weak ε\varepsilon-approximations, where it is stronger than the former but weaker than the latter.

Keywords

Cite

@article{arxiv.1810.10231,
  title  = {Extending the centerpoint theorem to multiple points},
  author = {Alexander Pilz and Patrick Schnider},
  journal= {arXiv preprint arXiv:1810.10231},
  year   = {2018}
}

Comments

Presented at the 29th International Symposium on Algorithms and Computation (ISAAC 2018)

R2 v1 2026-06-23T04:50:54.629Z