The de Grey-Haugstrup graphs are two 6-chromatic graphs on 47 and 48 vertices that are unit-distance in 3 dimensions (de Grey and Haugstrup 2020).
de Grey-Haugstrup Graphs
See also
de Grey Graphs, Unit-Distance GraphExplore with Wolfram|Alpha
References
de Grey, A. and Haugstrup, A. "Two Small 6-Chromatic Unit-Distance Graphs in
." Geocombinatorics 30, 5-13, 2020.
Cite this as:
Weisstein, Eric W. "de Grey-Haugstrup Graphs." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/deGrey-HaugstrupGraphs.html