Higher limits over the fusion orbit category via subgroup complexes
Abstract
Let β± be a saturated fusion system over a finite p-group S, and πͺc (β±) denote the centric orbit category of β±. Suppose that G is a discrete group realizing β±, and π is the collection of all p-centric subgroups in G. We prove that for every β€(p) πͺ c (β±)-module M, the higher limits lim * πͺc (β±) M are isomorphic to the equivariant cohomology HG * (|π| ; β³ ), where β³ is the G-equivariant coefficient system on |π| induced by M. This is the fusion system version of a theorem by Grodal for higher limits over the p-orbit category πͺp(G) of a finite group G. As a consequence, for every fusion system β±, we obtain a finite sequence of cohomology groups, involving the cohomology of β±, which is exact if and only if the mod-p subgroup decomposition for β± over β±-centric subgroups is sharp.
Related
- Minimal slN Complexes of Rational Tangles via the Fukaya Category
- One-periodic category of twisted complexes, Cohen-Macaulay modules and differential modules
- Day Convolution and Homotopy Groups on the Pointed Homotopy Category of CW Complexes
- A diagrammatic presentation for every pivotal pointed fusion category
- A vertex operator algebra for the S-fold realisation of a non-unitary Haagerup--Izumi modular fusion category
BibTeX
@misc{yalcin2026higher,
title = {{Higher limits over the fusion orbit category via subgroup complexes}},
author = {Ergun Yalcin},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.40915},
eprint = {2610.40915},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.40915},
}
RIS
TY - UNPB
TI - Higher limits over the fusion orbit category via subgroup complexes
AU - Ergun Yalcin
PY - 2026
DA - 2026/10/29
PB - arXiv
DO - 10.48550/arxiv.2610.40915
UR - https://arxiv.org/abs/2610.40915
AB - Let β± be a saturated fusion system over a finite p-group S, and πͺ^c (β±) denote the centric orbit category of β±. Suppose that G is a discrete group realizing β±, and π is the collection of all p-centric subgroups in G. We prove that for every β€_(p) πͺ ^c (β±)-module M, the higher limits lim ^* _πͺ^c (β±) M are isomorphic to the equivariant cohomology H_G ^* (|π| ; β³ ), where β³ is the G-equivariant coefficient system on |π| induced by M. This is the fusion system version of a theorem by Grodal for higher limits over the p-orbit category πͺ_p(G) of a finite group G. As a consequence, for every fusion system β±, we obtain a finite sequence of cohomology groups, involving the cohomology of β±, which is exact if and only if the mod-p subgroup decomposition for β± over β±-centric subgroups is sharp.
ER -