%0 Journal Article
%T Planar 4-critical graphs with four triangles
%A Oleg V. Borodin
%A Zden¨§k Dvo£¿¨¢k
%A Alexandr V. Kostochka
%A Bernard Lidicky
%A Matthew Yancey
%J Computer Science
%D 2013
%I arXiv
%X By the Grunbaum-Aksenov Theorem (extending Grotzsch's Theorem) every planar graph with at most three triangles is 3-colorable. However, there are infinitely many planar 4-critical graphs with exactly four triangles. We describe all such graphs. This answers a question of Erdos from 1990.
%U http://arxiv.org/abs/1306.1477v1