On September 26, 2012, Nissan North America, Inc., filed IPR2012-00035 IPR2012-00037 against Jackson walker LLP on U.S. Patent Nos. 5411797 and 5478650  Synopsys, Inc., also filed IPR2012-00041 and IPR2012-00042 agaomst Mentor Graphics Corporation on U.S. Patent Nos. 6947882 and 6240376.