module Data.Graph.Inductive.Query.Indep (indep) where
{ import Data.Graph.Inductive.Graph;
   
  first :: (a -> Bool) -> [a] -> a;
  first p = head . filter p;
   
  indep :: (DynGraph gr) => gr a b -> [Node];
  indep g | isEmpty g = [];
  indep g = if length i1 > length i2 then i1 else i2
    where { vs = nodes g;
            m = maximum (map (deg g) vs);
            v = first (\ v' -> deg g v' == m) vs;
            (Just c, g') = match v g;
            i1 = indep g';
            i2 = v : indep (delNodes (neighbors' c) g')}}
