Joel Friedman Andreas Goerdt Michael Krivelevich Recognizing More Unsatisfiable Random k-SAT Instances Efficiently. 408-430 2005 35 SIAM J. Comput. 2 http://epubs.siam.org/SICOMP/volume-35/art_44096.html db/journals/siamcomp/siamcomp35.html#FriedmanGK05