Graphs without a 3-connected subgraph are 4-colorable
Édouard Bonnet, Carl Feghali, Tung Nguyen, Alex Scott, Paul Seym·2024-02-09·via math.CO updates on arXiv.org
In 1972, Mader showed that every graph without a 3-connected subgraph is 4-degenerate and thus 5-colorable}. We show that the number 5 of colors can be replaced by 4, which is best possible.