English

On finite group scheme-theoretical categories, II

Representation Theory 2025-09-12 v2

Abstract

Let C:=C(G,ω,H,ψ)\mathcal{C}:=\mathcal{C}(G,\omega,H,\psi) be a finite group scheme-theoretical category over an algebraically closed field of characteristic p0p\ge 0 as defined by the first author. For any indecomposable exact module category over C\mathcal{C}, we classify its simple objects and provide an expression for their projective covers in terms of double cosets and projective representations of certain closed subgroup schemes of GG. This upgrades a result of Ostrik for group-theoretical fusion categories in characteristic 00, and generalizes our previous work for the case ω=1\omega=1. As a byproduct, we describe the simples and indecomposable projectives of C\mathcal{C}. Finally, we apply our results to describe the blocks of the center of Coh(G,ω){\rm Coh}(G,\omega).

Keywords

Cite

@article{arxiv.2403.08785,
  title  = {On finite group scheme-theoretical categories, II},
  author = {Shlomo Gelaki and Guillermo Sanmarco},
  journal= {arXiv preprint arXiv:2403.08785},
  year   = {2025}
}
R2 v1 2026-06-28T15:19:07.895Z