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Graph Recoloring


Graph recoloring is the transformation of one proper vertex coloring of a graph into another by changing the color of one graph vertex at a time while keeping every intermediate coloring proper. The k-reconfiguration graph R_k(G) has the proper vertex colorings of G using k available colors as vertices, with two adjacent iff they differ at exactly one graph vertex. A graph G is recolorable if R_k(G) is connected for every k>=chi(G)+1, where chi(G) is the chromatic number.

Huang et al. (2026) proved that every clique blowup of the cycle graph C_n is recolorable iff n is 3, 4, 5, or 7. Here a clique blowup replaces each graph vertex by a nonempty clique and joins two replacement cliques completely precisely when their original vertices were adjacent. This differs from the independent vertex set replacement used in a graph blow-up.


See also

Chromatic Number, Vertex Coloring

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References

Cereceda, L.; van den Heuvel, J.; and Johnson, M. "Connectedness of the Graph of Vertex-Colourings." Disc. Math. 308, 913-919, 2008. https://doi.org/10.1016/j.disc.2007.07.028.Huang, T.; Ma, Y.; and Zhang, J. "Frozen Colorings and Recolorability of Blowups." 20 Oct 2026. https://arxiv.org/abs/2610.27527.

Cite this as:

Weisstein, Eric W. "Graph Recoloring." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/GraphRecoloring.html

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