English

A `converse' to the Constraint Lemma

Geometric Topology 2020-07-14 v3

Abstract

The main result is a direct proof of the implication (LVKFk,3)(LT3k1,3)(LVKF_{k,3})\Rightarrow( LT_{3k-1,3}) below. Consider the following statements: (LVKF1,3LVKF_{1,3}) From any 11 points in R3 \mathbb{R}^{3} one can choose 3 pairwise disjoint triples whose convex hulls have a common point. (LVKFk,3LVKF_{k,3}) From any 6k+56k + 5 points in R3k \mathbb{R}^{3k} one can choose 3 pairwise disjoint sets each containing 2k+12k + 1 points and whose convex hulls have a common point. (LT2,3LT_{2,3}) Any 7 points in R2\mathbb{R}^{2} can be decomposed into 3 subsets whose convex hulls have a common point. (LTd,3LT_{d,3}) Any 2d+32d+3 points in Rd\mathbb{R}^d can be decomposed into 3 subsets whose convex hulls have a common point. This statements are true, but the meaning of the article is the direct derivation of one statement from another.

Keywords

Cite

@article{arxiv.1903.08910,
  title  = {A `converse' to the Constraint Lemma},
  author = {Egor Kolpakov},
  journal= {arXiv preprint arXiv:1903.08910},
  year   = {2020}
}
R2 v1 2026-06-23T08:14:49.214Z