code: private Set<String> getLeastUbique(Collection<String> ids)
  	{
  		Set<String> select = new HashSet<String>();
  
  		int s = getLeastScore(ids);
  
  		for (String id : ids)
  		{
  			if (score.get(id) == s) select.add(id);
  		}
  
  		return select;
  	}
docs: Gets the subset with the least score.