On Minimal Triangle-Free 5-Chromatic Graphs
Charles M. Grinstead, Katinsky, Van Stone · Works - Scholarship, Research, & Creative Expression (Swarthmore College) · 1989
Avis has shown that the munber of vertices of a minimal triangle-free 5chromatic graph is no fewer than 19.Mycielski has shown that this number is no more than 23.In this paper, we improve these bounds to 21 and 22, respectively.