Basic Examples

Compute chromatic numbers of simple graphs:
[◼]
ChromaticNumber
[PetersenGraph[]]
In[]:=
3
Out[]=
Compute chromatic numbers of graphs:
[◼]
ChromaticNumber
/@,,
In[]:=
{3,3,2}
Out[]=
Compute the vertex chromatic number of famous graphs:
[◼]
ChromaticNumber
/@Table[GraphData[{"RookComplement",{n,n}}],{n,10}]
In[]:=
{1,2,3,4,5,6,7,8,9,10}
Out[]=

Scope

Works on graphs in either 2D or 3D form:
utility=GraphData["UtilityGraph",{"Graph","Graph3D"}]
In[]:=
Out[]=
[◼]
ChromaticNumber
/@utility
In[]:=
{2,2}
Out[]=
Special and corner cases are handled efficiently:
g=CompleteGraph[24];​​Labeledg,Text@StringTemplate["χ(g) = `1`"]
[◼]
ChromaticNumber
@g
In[]:=
Out[]=

Applications

Compute on larger graphs than was possible before (with
Combinatorica`
):
[◼]
ChromaticNumber
@//AbsoluteTiming
{1.24407,7}
Out[]=

Possible Issues

ChromaticNumber
does not work on the output of
GraphPlot
:
[◼]
ChromaticNumber
@GraphPlot[PetersenGraph[]]
In[]:=
[◼]
ChromaticNumber

Out[]=