The chromatic number of a graph is the minimum number of colours required to colour it.
Consider the following graph:
This graph has been coloured using colours. Furthermore, it’s clear that it cannot be coloured with fewer than colours, as well: it contains a subgraph () that is isomorphic to the complete graph of vertices. As a result, the chromatic number of this graph is indeed .
This example was easy to solve by inspection. In general, however, finding the chromatic number of a large graph (and, similarly, an optimal colouring) is a very difficult (NP-hard) problem.
|Date of creation||2013-05-16 21:23:44|
|Last modified on||2013-05-16 21:23:44|
|Last modified by||unlord (1)|