Planar Turán number of quasi-double stars

Huiqing Liu, Tian Xie, Qin Zhao

Given a graph H, we call a graph $\text{H-free}$ if it does not contain H as a subgraph. The planar Turán number of a graph H, denoted by $e{x}_{\mathcal{P}}(n,H)$, is the maximu…