SWI-Prolog -- complement/2

Availability::- use_module(library(ugraphs)).(can be autoloaded)

complement(+Graph, -NewGraph)

Unify NewGraph with the graph complementary to Graph. Example:

?- complement([1-[3,5],2-[4],3-[],
               4-[1,2,7,5],5-[],6-[],7-[],8-[]], NL).
NL = [1-[2,4,6,7,8],2-[1,3,5,6,7,8],3-[1,2,4,5,6,7,8],
      4-[3,5,6,8],5-[1,2,3,4,6,7,8],6-[1,2,3,4,5,7,8],
      7-[1,2,3,4,5,6,8],8-[1,2,3,4,5,6,7]]