A minimum vertex coloring of a graph is a vertex coloring that
uses the fewest possible colors. The task of finding one is the vertex
coloring problem. The number of colors in a minimum vertex coloring is the chromatic number
, and a graph with chromatic
number
is said to be a k-chromatic graph.
The Wolfram Language function FindVertexColoring[g] is documented to find a coloring with a minimum number of colors.
The number of minimum vertex colorings is given by , where
is the chromatic polynomial
of a graph and
is its chromatic number.