Jackson's conjecture on chromatic roots of 3-connected graphs

Let GG be a 3-connected graph that is not bipartite of odd order. A chromatic root is a real or complex zero of the chromatic polynomial P(G,x)P(G,x). Jackson's conjecture. The graph GG has no chromatic roots in (1,2)(1,2). This conjecture concerns extending the chromatic-root-free interval beyond the general bound 32/2732/27 for sufficiently connected non-bipartite graphs; the source gives no resolution.

Sources & referencesView supporting material

Primary source

Gordon F. Royle, “Graphs with chromatic roots in the interval (1,2)”, arXiv:0704.2264 (2007).

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