https://cel.archives-ouvertes.fr/cel-00762830 Contributor : Xavier GuyonConnect in order to contact the contributor Submitted on : Saturday, December 8, 2012 - 11:28:37 AM Last modification on : Friday, May 6, 2022 - 4:50:07 PM Long-term archiving on: : Saturday, March 9, 2013 - 2:55:10 AM