Anagram-Free Chromatic Number is not Pathwidth-Bounded

Abstract

The anagram-free chromatic number is a new graph parameter introduced independently Kam\v{c}ev, {\L}uczak, and Sudakov (2017) and Wilson and Wood (2017). In this note, we show that there are planar graphs of pathwidth 3 with arbitrarily large anagram-free chromatic number. More specifically, we describe $2n$-vertex planar graphs of pathwidth 3 with anagram-free chromatic number $\Omega(\log n)$. We also describe $kn$ vertex graphs with pathwidth $2k-1$ having anagram-free chromatic number in $\Omega(k\log n)$.