A universal formula for the j-invariant of the canonical lifting

Abstract

We study the j-invariant of the canonical lifting of an elliptic curve as a Witt vector. We prove that its Witt coordinates lie in an open affine subset of the j-line and deduce the existence of a universal formula for the j-invariant of the canonical lifting. The canonical lifting of the elliptic curves with j-invariant 0 and 1728 over any characteristic is also explicitly found. (C) 2015 Elsevier Inc. All rights reserved.