S. Bradde Alfredo Braunstein H. Mahmoudi F. Tria Martin Weigt Riccardo Zecchina Aligning graphs and finding substructures by message passing http://arxiv.org/abs/0905.1893 2009 CoRR abs/0905.1893 db/journals/corr/corr0905.html#abs-0905-1893 informal publication