Sharp planar Turán bounds for quasi-double stars

Zehui Shao, Enqiang Zhu, Shaohui Wang

We study $W$-free planar graphs for $W\in \{W_{2,4},W_{2,5},W_{3,4}\}$, where the quasi-double star $W_{h,k}$ is obtained from a three-vertex path by attaching $h$ leaves to one end…