https://cel.archives-ouvertes.fr/cel-01995410 Contributor : François SchwarzentruberConnect in order to contact the contributor Submitted on : Saturday, January 26, 2019 - 6:12:14 PM Last modification on : Wednesday, November 3, 2021 - 6:04:08 AM Long-term archiving on: : Saturday, April 27, 2019 - 12:59:01 PM