English

Frobenius-Witt differentials and regularity

Algebraic Geometry 2024-10-08 v5 Commutative Algebra Number Theory

Abstract

T. Dupuy, E. Katz, J. Rabinoff, D. Zureick-Brown introduced the module of total pp-differentials for a ring over Z/p2ZZ/p^2Z. We study the same construction for a ring over Z(p)Z_{(p)} and prove a regularity criterion. For a local ring, the tensor product with the residue field is constructed in a different way by O. Gabber, L. Ramero. In another article arXiv:2006.00448, we use the sheaf of FW-differentials to define the cotangent bundle and the micro-support of an etale sheaf.

Keywords

Cite

@article{arxiv.2008.04728,
  title  = {Frobenius-Witt differentials and regularity},
  author = {Takeshi Saito},
  journal= {arXiv preprint arXiv:2008.04728},
  year   = {2024}
}

Comments

22 pages. In v2, schemes are not used except in the last section. Earlier overlap in arXiv:2006.00448 is removed. An error in Lemma 1.3 pointed out by A. Mathew is corrected in v5

R2 v1 2026-06-23T17:46:44.516Z