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Egor Kolpakov

Publications and source records attributed to Egor Kolpakov.

2 recordsLinked to original sources

A `converse' to the Constraint Lemma

The main result is a direct proof of the implication $(LVKF_{k,3})\Rightarrow( LT_{3k-1,3})$ below. Consider the following statements: ($LVKF_{1,3}$) From any 11 points in $ \mathbb{R}^{3}$ one can choose 3 pairwise disjoint triples whose convex hulls have a common point. ($LVKF_{k,3}$) From any $6k + 5$ points in $ \mathbb{R}^{3k}$ one can choose 3 pairwise disjoint sets each containing $2k + 1 $ points and whose convex hulls have a common point. ($LT_{2,3}$) Any 7 points in $\mathbb{R}^{2}$ can be decomposed into 3 subsets whose convex hulls have a common point. ($LT_{d,3}$) Any $2d+3$ points in $\mathbb{R}^d$ 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.

math.GT

Proof of Radon's theorem by lowering the dimension

There is the classical Radon theorem. Given integer $d \geq 1$ and $d+2$ points in d-dimensional space $R^d$. Then these points can be divided into two disjoint subsets whose convex hulls have a non-empty intersection. The original proof of this theorem is usually used. In this article, this is another proof of it, by lowering the dimension.

math.MG