English

Group actions on contractible $2$-complexes II

Algebraic Topology 2025-08-22 v2 Group Theory Representation Theory

Abstract

In this second part we prove that, if GG is one of the groups PSL2(q)\mathrm{PSL}_2(q) with q>5q>5 and q5(mod24)q\equiv 5\pmod {24} or q13(mod24)q\equiv 13 \pmod{24}, then the fundamental group of every acyclic 22-dimensional, fixed point free and finite GG-complex admits a nontrivial representation in a unitary group U(m)\mathrm{U}(m). This completes the proof of the following result: every action of a finite group on a finite and contractible 22-complex has a fixed point.

Keywords

Cite

@article{arxiv.2102.11459,
  title  = {Group actions on contractible $2$-complexes II},
  author = {Kevin Ivan Piterman and Iván Sadofschi Costa},
  journal= {arXiv preprint arXiv:2102.11459},
  year   = {2025}
}

Comments

To appear in Inventiones mathematicae

R2 v1 2026-06-23T23:25:34.891Z