Lars Engebretsen Jonas Holmerin Towards Optimal Lower Bounds For Clique and Chromatic Number Electronic Colloquium on Computational Complexity (ECCC) 2001 8 3 db/journals/eccc/eccc8.html#ECCC-TR01-003 http://eccc.hpi-web.de/eccc-reports/2001/TR01-003/index.html