MathDB
IMC 2003 Problem 9

Source: IMC 2003 Day 2 Problem 3

November 2, 2020
densetopologyreal analysiscollege contestsIMC

Problem Statement

Let AA be a closed subset of Rn\mathbb{R}^{n} and let BB be the set of all those points bRnb \in \mathbb{R}^{n} for which there exists exactly one point a0Aa_{0}\in A such that a0b=infaAab|a_{0}-b|= \inf_{a\in A}|a-b|. Prove that BB is dense in Rn\mathbb{R}^{n}; that is, the closure of BB is Rn\mathbb{R}^{n}