Problems related to a de Bruijn - Erdős theorem

Xiaomin Chen, Vašek Chvátal

Published 2006-10-01Version 1

De Bruijn and Erd\H{o}s proved that every noncollinear set of n points in the plane determines at least n distinct lines. We suggest a possible generalization of this theorem in the framework of metric spaces and provide partial results on related extremal combinatorial problems.