English

Modules with finitely generated cohomology

Representation Theory 2023-08-21 v1

Abstract

Let GG be a finite group and k\mathsf{k} a field of characteristic pp. It is conjectured in a paper of the first author and John Greenlees that the thick subcategory of the stable module category StMod(kG)(\mathsf{k}G) consisting of modules whose cohomology is finitely generated over H(G,k)\mathsf{H}^*(G,\mathsf{k}) is generated by finite dimensional modules and modules with no cohomology. If the centraliser of every element of order pp in GG is pp-nilpotent, this statement follows from previous work. Our purpose here is to prove this conjecture in two cases with non pp-nilpotent centralisers. The groups involved are Z/3r×Σ3{\mathbb Z}/3^r\times\Sigma_3 (r>0r> 0) in characteristic three and Z/2×A4{\mathbb Z}/2\times A_4 in characteristic two. As a consequence, in these cases the bounded derived category of CBGC^*BG (cochains on BGBG with coefficients in k\mathsf{k}) is generated by CBSC^*BS, where SS is a Sylow pp-subgroup of GG.

Keywords

Cite

@article{arxiv.2308.09579,
  title  = {Modules with finitely generated cohomology},
  author = {David J. Benson and Jon F. Carlson},
  journal= {arXiv preprint arXiv:2308.09579},
  year   = {2023}
}

Comments

11 pages

R2 v1 2026-06-28T11:58:48.442Z