Lutz Kettner Kurt Mehlhorn Sylvain Pion Stefan Schirra Chee-Keng Yap Classroom examples of robustness problems in geometric computations. 61-78 2008 40 Comput. Geom. 1 http://dx.doi.org/10.1016/j.comgeo.2007.06.003 db/journals/comgeo/comgeo40.html#KettnerMPSY08