Jérémie Bettinelli École polytechnique Laboratoire d'informatique (LIX) 91128 Palaiseau Cedex FRANCE E-mail: firstname « . » lastname « at » normalesup « . » org Office: 2023 Phone: (+33) (0)1 77 57 80 61

Désolé, pas de version française

Each jpg picture (except cylinders, pairs of pants and geodesic cliques) is also available in pdf format: click the picture and manually replace jpg by pdf at the end of the address. Beware that the pdf files are quite large. The jpg and gif files are of reasonable size and quality but if you want better quality jpg pictures, I can provide them upon simple request.