Metric $1$-median selection: Query complexity vs. approximation ratio

Abstract

Consider the problem of finding a point in a metric space $(\{1,2,\ldots,n\},d)$ with the minimum average distance to other points. We show that this problem has no deterministic $o(n^{1+1/(h-1)})$-query $(2h-\Omega(1))$-approximation algorithms for any constant $h\in\mathbb{Z}^+\setminus\{1\}$.