Acyclic 4-choosability of planar graphs without 4-cycles

Sun, Yingcai ; Chen, Min

Czechoslovak Mathematical Journal, Tome 70 (2020) no. 1, pp. 161-178.

Résumé

A proper vertex coloring of a graph $G$ is acyclic if there is no bicolored cycle in $G$. In other words, each cycle of $G$ must be colored with at least three colors. Given a list assignment $L=\{L(v)\colon v\in V\}$, if there exists an acyclic coloring $\pi $ of $G$ such that $\pi (v)\in L(v)$ for all $v\in V$, then we say that $G$ is acyclically $L$-colorable. If $G$ is acyclically $L$-colorable for any list assignment $L$ with $|L(v)|\ge k$ for all $v\in V$, then $G$ is acyclically $k$-choosable. In 2006, Montassier, Raspaud and Wang conjectured that every planar graph without 4-cycles is acyclically 4-choosable. However, this has been as yet verified only for some restricted classes of planar graphs. In this paper, we prove that every planar graph with neither 4-cycles nor intersecting $i$-cycles for each $i\in \{3,5\}$ is acyclically 4-choosable.

Détail

DOI : 10.21136/CMJ.2019.0197-18

Classification : 05C10, 05C15
Keywords: planar graph; acyclic coloring; choosability; intersecting cycle