size package:fgl

The number of edges in the graph. Note that this counts every edge found, so if you are representing an unordered graph by having each edge mirrored this will be incorrect. If you created an unordered graph by either mirroring every edge (including loops!) or using the undir function in Data.Graph.Inductive.Basic then you can safely halve the value returned by this.
The maximum independent node set along with its size.