Small odd cycles in 4-chromatic graphs
\textit{A. Nilli} [J. Graph Theory 31, No. 2, 145-147 (1999; Zbl 0924.05044)] showed that every 4-chromatic graph on \(n\) vertices contains an odd cycle of length less than \(\sqrt{8n}\). The author improves this bound to \(2\sqrt{n}+3\).
scientific article; zbMATH DE number 1652667