Angeltveit, Vigleik2015-09-162015-09-161631-073Xhttp://hdl.handle.net/1885/15434We discuss a multiplicative version of the Verschiebung map of Witt vectors that we call the norm.The author was supported by the Australian Research Council Discovery Grant (No. DP120101399).6 pages© 2015 Académie des sciences. Published by Elsevier Masson SAS. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ https://www.elsevier.com/about/our-business/policies/sharing/how-to-attach-a-user-license (Publisher journal website 5/9/2017) http://www.sherpa.ac.uk/romeo/issn/1631-073X/ Author's post-print on open access repository after an embargo period of 12 months (Sherpa/Romeo 5/9/2017)multiplicative versionVerschiebung mapWitt vectorsnorm2015-0510.1016/j.crma.2015.02.014