
theorem Th75:
for G being SimpleGraph, C being StableSet of Complement G
  holds G SubgraphInducedBy C is Clique of G
proof
 let G be SimpleGraph, C be StableSet of Complement G;
   (Complement Complement G) SubgraphInducedBy C
       is Clique of Complement Complement G by Th74;
 hence G SubgraphInducedBy C is Clique of G;
end;
