English

Unipotent morphisms

Algebraic Geometry 2026-05-06 v2

Abstract

We introduce the theory of unipotent morphisms of algebraic stacks and prove a surprising local to global principle for a class of vector bundles. Two sample applications of our methods are the following: (1) a unipotent analogue of Gabber's Theorem for torsion Gm\mathbf{G}_m-gerbes and (2) smooth Deligne-Mumford stacks with quasi-projective coarse spaces satisfy the resolution property in positive characteristic. Our main tool is a descent result for flags, which we prove using results of Sch\"appi.

Keywords

Cite

@article{arxiv.2110.15041,
  title  = {Unipotent morphisms},
  author = {Daniel Bragg and Jack Hall and Siddharth Mathur},
  journal= {arXiv preprint arXiv:2110.15041},
  year   = {2026}
}

Comments

Final version, to appear in Geometry & Topology

R2 v1 2026-06-24T07:15:43.766Z