The basic geometry of Witt vectors, I: The affine case

Borger, James

doi:10.2140/ant.2011.5.231

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The basic geometry of Witt vectors, I The affine case

James Borger

Vol. 5 (2011), No. 2, 231–285

DOI: 10.2140/ant.2011.5.231

Abstract

We give a concrete description of the category of étale algebras over the ring of Witt vectors of a given finite length with entries in an arbitrary ring. We do this not only for the classical $p$ -typical and big Witt vector functors but also for certain analogues over arbitrary local and global fields. The basic theory of these generalized Witt vectors is developed from the point of view of commuting Frobenius lifts and their universal properties, which is a new approach even for classical Witt vectors. Our larger purpose is to provide the affine foundations for the algebraic geometry of generalized Witt schemes and arithmetic jet spaces, so the basics are developed in some detail, with an eye toward future applications.

Keywords

Witt vector, Witt space, lambda-ring, Frobenius lift, plethory

Mathematical Subject Classification 2010

Primary: 13F35

Milestones

Received: 13 May 2010

Revised: 8 August 2010

Accepted: 13 October 2010

Published: 27 August 2011

Authors

James Borger
Department of Mathematics Australian National University Mathematical Sciences Institute Building 27 Canberra 2602 Australia
http://wwwmaths.anu.edu.au/~borger/

Vol. 5, No. 2, 2011