On planar and non-planar graphs having no chromatic zeros in the interval(1,2) (Q932643)

A chromatic zero of a graph \(G\) is a zero of the chromatic polynomial of \(G\). A near-triangulation is a loopless connected plane graph having at most one non-triangular face. The authors describe a family of 2-connected graphs closed under certain operations and having no chromatic zeros in \((1,2)\). The family contains collections of graphs avoiding certain minors and also collections of plane graphs, including near-triangulation found by \textit{G. Birkhoff} and \textit{D. G. Lewis} [Trans. Am. Math. Soc. 60, 355--451 (1946; Zbl 0060.41601)].