https://cel.archives-ouvertes.fr/cel-00136497 Contributor : Emmanuel MoulayConnect in order to contact the contributor Submitted on : Wednesday, March 14, 2007 - 11:14:55 AM Last modification on : Wednesday, April 27, 2022 - 4:41:41 AM Long-term archiving on: : Friday, September 21, 2012 - 12:55:15 PM