English

List recoloring of planar graphs

Combinatorics 2022-11-30 v2 Discrete Mathematics

Abstract

A list assignment LL of a graph GG is a function that assigns to every vertex vv of GG a set L(v)L(v) of colors. A proper coloring α\alpha of GG is called an LL-coloring of GG if α(v)L(v)\alpha(v)\in L(v) for every vV(G)v\in V(G). For a list assignment LL of GG, the LL-recoloring graph G(G,L)\mathcal{G}(G,L) of GG is a graph whose vertices correspond to the LL-colorings of GG and two vertices of G(G,L)\mathcal{G}(G,L) are adjacent if their corresponding LL-colorings differ at exactly one vertex of GG. A dd-face in a plane graph is a face of length dd. Dvo\v{r}\'ak and Feghali conjectured for a planar graph GG and a list assignment LL of GG, that: (i) If L(v)10|L(v)|\geq 10 for every vV(G)v\in V(G), then the diameter of G(G,L)\mathcal{G}(G,L) is O(V(G))O(|V(G)|). (ii) If GG is triangle-free and L(v)7|L(v)|\geq 7 for every vV(G)v\in V(G), then the diameter of G(G,L)\mathcal{G}(G,L) is O(V(G))O(|V(G)|). In a recent paper, Cranston (European J. Combin. (2022)) has proved (ii). In this paper, we prove the following results. Let GG be a plane graph and LL be a list assignment of GG. \bullet If for every 33-face of GG, there are at most two 33-faces adjacent to it and L(v)10|L(v)|\geq 10 for every vV(G)v\in V(G), then the diameter of G(G,L)\mathcal{G}(G,L) is at most 190V(G)190|V(G)|. \bullet If for every 33-face of GG, there is at most one 33-face adjacent to it and L(v)9|L(v)|\geq 9 for every vV(G)v\in V(G), then the diameter of G(G,L)\mathcal{G}(G,L) is at most 13V(G)13|V(G)|. \bullet If the faces adjacent to any 33-face have length at least 66 and L(v)7|L(v)|\geq 7 for every vV(G)v\in V(G), then the diameter of G(G,L)\mathcal{G}(G,L) is at most 242V(G)242|V(G)|. This result strengthens the Cranston's result on (ii).

Keywords

Cite

@article{arxiv.2209.05992,
  title  = {List recoloring of planar graphs},
  author = {L. Sunil Chandran and Uttam K. Gupta and Dinabandhu Pradhan},
  journal= {arXiv preprint arXiv:2209.05992},
  year   = {2022}
}
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