Roberto Grossi Alessio Orlandi Rajeev Raman S. Srinivasa Rao More Haste, Less Waste: Lowering the Redundancy in Fully Indexable Dictionaries http://arxiv.org/abs/0902.2648 2009 CoRR abs/0902.2648 db/journals/corr/corr0902.html#abs-0902-2648 informal publication