Some useful miscellaneous components.
AUTHORS:
Compute the independence number of ‘graph’.
A list of those vertices in ‘graph’ which have ‘colour’ in the list associated with that vertex by ‘list_assignment’.
The subgraph induced by those vertices of ‘graph’ which have ‘colour’ in the list associated by ‘list_assignment’.
Change a mapping of vertices to colours into a mapping of colours to vertices.