private void cluster(Node less) {
      Node similiar1 = null;
      Node similiar2 = null;
      int sim1 = 0;
      int sim2 = 0;
      double distance = 8000.0;
      // suche die aehnlichsten Blaetter
      for (int i = 0; i < less.getNodes().length; i++) {
         Node node1 = less.getNode(i);
         if (node1 != null) {
            for (int j = (i + 1); j < less.getNodes().length; j++) {
               Node node2 = less.getNode(j);
               if (node2 != null) {
                  Double newDistance = getDistance(node1, node2);
                  if (newDistance != null && newDistance < distance) {
                     distance = newDistance;
                     similiar1 = node1;
                     sim1 = i;
                     similiar2 = node2;
                     sim2 = j;
                  }
               }
            }
         }
      }
      if (similiar1 != null && similiar2 != null) {
         // do nothing
      }
      // merge die aehnlichsten
      mergeTwoNodes(less, sim1, sim2);
   }