TIME: 1:30-2:20 pm, November 7, 2006 PLACE: CSE 403 TITLE: Witnesses for non-satisfiability of dense random 3CNF formulas SPEAKER: Uri Feige Microsoft Research and Weizmann Institute of Science ABSTRACT: We consider random 3CNF formulas with n variables and m clauses. It is well known that when m > cn (for a sufficiently large constant c), most formulas are not satisfiable. However, it is not known whether such formulas are likely to have polynomial size witnesses that certify that they are not satisfiable. We show that when m > cn^{7/5} almost all 3CNF formulas have polynomial size witnesses for nonsatisfiability. Joint work with Jeong Han Kim and Eran Ofek