English

On CW-complexes over groups with periodic cohomology

Algebraic Topology 2021-10-05 v3 Group Theory K-Theory and Homology

Abstract

If GG has 44-periodic cohomology, then D2 complexes over GG are determined up to polarised homotopy by their Euler characteristic if and only if GG has at most two one-dimensional quaternionic representations. We use this to solve Wall's D2 problem for several infinite families of non-abelian groups and, in these cases, also show that any finite Poincar\'{e} 33-complex XX with π1(X)=G\pi_1(X)=G admits a cell structure with a single 33-cell. The proof involves cancellation theorems for ZG\mathbb{Z} G modules where GG has periodic cohomology.

Keywords

Cite

@article{arxiv.1905.12018,
  title  = {On CW-complexes over groups with periodic cohomology},
  author = {John Nicholson},
  journal= {arXiv preprint arXiv:1905.12018},
  year   = {2021}
}

Comments

27 pages. Added new Corollary relating to a conjecture of J. M. Cohen in final section, small changes to layout and references, fixed minor errors. Final version, to appear in Transactions of the American Mathematical Society

R2 v1 2026-06-23T09:29:53.571Z