English

Contramodules for algebraic groups: induction and projective covers

Representation Theory 2024-11-04 v3

Abstract

In this paper we will investigate contramodules for algebraic groups. Namely, we give contra-analogs to two 20th century results about comodules. Firstly, we show that induction of contramodules over coordinate rings of algebraic groups is exact if and only if the associated quotient variety is affine. Secondly, we give an inverse limit theorem for constructing projective covers of simple GG-modules using GG-structures of projective covers of simple modules for the first Frobenius kernel, G1G_1.

Keywords

Cite

@article{arxiv.2304.07525,
  title  = {Contramodules for algebraic groups: induction and projective covers},
  author = {Dylan Johnston},
  journal= {arXiv preprint arXiv:2304.07525},
  year   = {2024}
}

Comments

Updated to essentially match journal submission. Includes restructuring of results, typo fixes etc. 19 pages

R2 v1 2026-06-28T10:06:54.482Z