Planar Turán number of two adjacent cycles

Xinzhe Song, Guiying Yan, Qiang Zhou

The planar Turán number of $H$, denoted by $e{x}_{\mathcal{P}}(n,H)$, is the maximum number of edges in an $n$-vertex $H$-free planar graph. The planar Turán number of $k(k\ge 3)$…