The exact Turán number of the even wheel $W_{2k+2}$ among non-$3$-partite graphs

Qixuan Yuan, Ruifang Liu, Sanming Zhou

Let $\mathrm{ex}(n,H)$ denote the Turán number of $H$. A graph is color-critical if there exists an edge $e\in E(H)$ such that $\chi (H-e)<\chi (H)$. For a color-critical graph $H$ with $χ…