Hadwiger-Nelson Problem

Author

Eric W. Weisstein
May 7, 2018

This notebook downloaded from http://mathworld.wolfram.com/notebooks/GraphTheory/Hadwiger-NelsonProblem.nb.

For more information, see Eric's MathWorld entry http://mathworld.wolfram.com/Hadwiger-NelsonProblem.html.

©2018 Wolfram Research, Inc. except for portions noted otherwise

Unit-distance graphs sorted by chromatic number

Triangle-free

TextGrid[Function[g,{g[[1,1]],TextGrid[{#[[1,1]],#[[All,2]]}&/@SplitBy[Sort[GraphData[#,{"V","#"}]&/@g[[All,2]]],First]]}]/@SplitBy[Sort[GraphData[#,{"ChromaticNumber","#"}]&/@GraphData[{"TriangleFree","UnitDistance"}]],First],Dividers->All,Alignment->Left]

All

TextGrid[Function[g,{g[[1,1]],TextGrid[{#[[1,1]],#[[All,2]]}&/@SplitBy[Sort[GraphData[#,{"V","#"}]&/@g[[All,2]]],First]]}]/@SplitBy[Sort[GraphData[#,{"ChromaticNumber","#"}]&/@GraphData["UnitDistance"]],First],Dividers->All,Alignment->Left]