A de Bruijn - Erdős theorem and metric spaces

Ehsan Chiniforooshan, Vašek Chvátal

Published 2009-05-31Version 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. Chen and Chv\'atal suggested a possible generalization of this theorem in the framework of metric spaces. We provide partial results in this direction.