List colouring triangle free planar graphs
Jianzhang Hu, Xuding Zhu
TL;DR
If G is a triangle free planar graph and L is a list assignment of G such that $\mid L(v)mid = 4$ for each vertex of G, then G is L-colourable.
Abstract
This paper proves the following result: Assume $G$ is a triangle free planar graph, $X$ is an independent set of $G$. If $L$ is a list assignment of $G$ such that $\mid L(v)\mid = 4$ for each vertex $v \in V(G)-X$ and $\mid L(v)\mid = 3$ for each vertex $v \in X$, then $G$ is $L$-colourable.
