rw calculates rank-width and rank-decompositions. It is based on ideas from
"Computing rank-width exactly" by Sang-il Oum, "Sopra una formula numerica" by
Ernesto Pascal, "Generation of a Vector from the Lexicographical Index" by B.P.
Buckles and M. Lybanon and "Fast additions on masked integers" by Michael D.
Adams and David S. Wise.

WWW: https://sourceforge.net/projects/rankwidth/