Andrea Scozzari Fabio Tardella On the Complexity of Graph-Based Bounds for the Probability Bounding Problem. 235-238 2009 CTW http://www.lix.polytechnique.fr/ctw09/ctw09-proceedings.pdf#page=247 conf/colognetwente/2009 db/conf/colognetwente/colognetwente2009.html#ScozzariT09