The Wormald graph is a unit-distance 4-chromatic graph with girth 5 on vertices.
Wormald Graph
See also
Girth, Unit-Distance GraphExplore with Wolfram|Alpha
References
Soifer, A. "Wormald's Application." §12.3 in The Mathematical Coloring Book: Mathematics of Coloring and the Colorful Life of Its Creators. New York: Springer, pp. 41 and 86-87, 2008.Wormald, N. C. "A 4-Chromatic Graph with a Special Plane Drawing." J. Austral. Math. Soc. 28, 1-8, 1979.Cite this as:
Weisstein, Eric W. "Wormald Graph." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/WormaldGraph.html