Symposium on Computational Geometry Proceedings 27th Annual ACM Symposium on Computational Geometry (SoCG'11, Paris, France, June 13-15, 2011), 407-416 STARTPAGE=407;ENDPAGE=416;TITLE=Proceedings 27th Annual ACM Symposium on Computational Geometry (SoCG'11, Paris, France, June 13-15, 2011)