Kostochka–Woodall list square coloring conjecture

For a graph GG, its square G2G^2 is the graph on V(G)V(G) in which two vertices are adjacent when their distance in GG is at most two. Let χ\chi and χ\chi_\ell denote the chromatic and list chromatic numbers. Kostochka–Woodall's conjecture. For any graph GG,

χ(G2)=χ(G2).\chi_\ell(G^2)=\chi(G^2).

The conjecture arose from the identity between total graphs and squares of suitably subdivided graphs; the supplied text gives no general resolution.

Equivalent formulations 1

Other statements of this same problem, merged from separate entries. Each is equivalent to the statement above — proving any one settles them all.

  1. Kostochka–Woodall List Square Coloring Conjecture

    For a simple graph GG, define its square G2G^2 by

    V(G2)=V(G),V(G^2)=V(G),

    and join two vertices xx and yy when their distance in GG is at most 22. List Square Coloring Conjecture. For any graph GG,

    χl(G2)=χ(G2).\chi_l(G^2)=\chi(G^2).

    The conjecture asks whether every square of a graph is chromatic-choosable; the source gives no resolution, and this paper presents counterexamples to it.

    source: Seog-Jin Kim and Boram Park, “Counterexamples to the List Square Coloring Conjecture”, arXiv:1305.2566 (2013).

Sources & referencesView supporting material

Primary source

Nandana K Vasudevan, K Somasundaram and N Narayanan, “List-Coloring and Chromatic-Choosability – A Dynamic Survey”, arXiv:2606.31702 (2026).

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