MathDB
IMC 2014, Problem 9

Source: IMC 2014

July 27, 2016
IMCcollege contestsset theory

Problem Statement

We say that a subset of Rn\mathbb{R}^n is kk-almost contained by a hyperplane if there are less than kk points in that set which do not belong to the hyperplane. We call a finite set of points kk-generic if there is no hyperplane that kk-almost contains the set. For each pair of positive integers (k,n)(k, n), find the minimal number of d(k,n)d(k, n) such that every finite kk-generic set in Rn\mathbb{R}^n contains a kk-generic subset with at most d(k,n)d(k, n) elements.
(Proposed by Shachar Carmeli, Weizmann Inst. and Lev Radzivilovsky, Tel Aviv Univ.)