English

The endomorphism ring of the trivial module in a localized category

Representation Theory 2022-10-05 v1

Abstract

Suppose that GG is a finite group and kk is a field of characteristic p>0p >0. Let M\mathcal{M} be the thick tensor ideal of finitely generated modules whose support variety is in a fixed subvariety VV of the projectivized prime ideal spectrum ProjH(G,k)\operatorname{Proj} \operatorname{H}^*(G,k). Let C\mathcal{C} denote the Verdier localization of the stable module category stmod(kG)\operatorname{stmod}(kG) at M\mathcal{M}. We show that if VV is a finite collection of closed points and if the pp-rank every maximal elementary abelian pp-subgroups of GG is at least 3, then the endomorphism ring of the trivial module in C\mathcal{C} is a local ring whose unique maximal ideal is infinitely generated and nilpotent. In addition, we show an example where the endomorphism ring in C\mathcal{C} of a compact object is not finitely presented as a module over the endomorphism ring of the trivial module.

Keywords

Cite

@article{arxiv.2210.01424,
  title  = {The endomorphism ring of the trivial module in a localized category},
  author = {Jon F. Carlson},
  journal= {arXiv preprint arXiv:2210.01424},
  year   = {2022}
}

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21 pages