Konstantinos Georgiou Avner Magen Toniann Pitassi Iannis Tourlakis Integrality gaps of 2 - o(1) for Vertex Cover SDPs in the Lovész-Schrijver Hierarchy. 702-712 2007 FOCS http://doi.ieeecomputersociety.org/10.1109/FOCS.2007.34 conf/focs/2007 db/conf/focs/focs2007.html#GeorgiouMPT07