Reconfiguring colorings of graphs with bounded maximum average degree

Abstract

The reconfiguration graph $R_k(G)$ for the $k$-colorings of a graph $G$ has as vertex set the set of all possible $k$-colorings of $G$ and two colorings are adjacent if they differ in the color of exactly one vertex of $G$. Let $d,k\ge 1$ be integers such that $k\ge d+1$. We prove that for every $\epsilon >0$ and every graph $G$ with $n$ vertices and maximum average degree $d-\epsilon$, $R_k(G)$ has diameter $O(n(\log n{)}^{d-1})$. This significantly strengthens several existing results.

7 pages; minor clarifications beyond the published version