So instead of trying to produce a general algorithm for finding Hamiltonian cycles, some mathematicians have focused on the easier problem of proving that particular types of graphs contain such cycles. In 2002, Michael Krivelevich of Tel Aviv University and Benny Sudakov, now at the Swiss Federal Institute of Technology Zurich, conjectured that an important class of graphs called expander graphs all contain Hamiltonian cycles. In February, together with four other mathematicians, Sudakov succee...