Xie, Litong; Liu, Guizhen On Whitney’s and Tutte’s conjecture. (Chinese. English summary) Zbl 0835.05025 Acta Math. Sin. 38, No. 3, 289-293 (1995). Whitney and Tutte studied the four color problem by transforming it into a problem on 4-colorings of circuits. They proposed a conjecture that implies the four color problem. In this paper, the authors show that this conjecture is not true. Reviewer: Liu Yanpei (Beijing) MSC: 05C15 Coloring of graphs and hypergraphs Keywords:open set; combinatorial operation; four color problem; circuits PDF BibTeX XML Cite \textit{L. Xie} and \textit{G. Liu}, Acta Math. Sin. 38, No. 3, 289--293 (1995; Zbl 0835.05025)