A new bound on the cyclic chromatic number
Abbreviated Journal Title
J. Comb. Theory Ser. B
In 1969, Ore and Plummer defined an angular coloring as a natural extension of the Four Color Problem: a face coloring of a plane graph where faces meeting even at a vertex must have distinct colors. A natural lower bound is the maximum degree Delta of the graph. Some graphs require left perpendicular 3/2 Delta right perpendicular colors in an angular coloring. Ore and Plummer gave an upper bound of 2 Delta, which was improved to left perpendicular 9/5 right perpendicular by the authors with Borodin. This article gives a new upper bound of inverted right perpendicular 5/9 Delta inverted left perpendicular on the angular chromatic number. The cyclic chromatic number is the equivalent dual vertex coloring problem. (C) 2001 Academic Press.
Journal of Combinatorial Theory Series B
"A new bound on the cyclic chromatic number" (2001). Faculty Bibliography 2000s. 8196.