English

A genuine equivariant recognition principle for finite groups

Algebraic Topology 2025-08-07 v1

Abstract

For GG a finite group and VV a finite dimensional real GG-representation, there is a GG-operad EV\mathbb{E}_{V} defined using embeddings of VV-framed GG-disks such that for any based GG-space XX, there is a naturally defined EV\mathbb{E}_{V}-algebra structure on the VV-fold space ΩVX\Omega^V X. Given an EV\mathbb{E}_{V}-algebra in GG-spaces and a subgroup HH of GG, the fixed points AHA^H carry the structure of an EdimVH\mathbb{E}_{\dim V^H}-algebra in spaces. We prove that an EV\mathbb{E}_{V}-algebra is equivalent to a VV-fold loop space if and only if AHA^H is group-like for all HH such that dimVH1\dim V^H \ge 1. This generalizes a result by Guillou and May by removing the assumption that VV contains a trivial summand. They observed that equivariant recognition principle follows from an equivariant version of the approximation theorem, stating that ΩVΣVX\Omega^V \Sigma^V X is the free group-like EV\mathbb{E}_{V}-algebra on a based GG-space XX. This has been proven by Hauschild in the case that VV contains a trivial summand and by Rourke and Sanderson in the case that XX is GG-connected. Our proof proceeds by showing that the equivariant approximation theorem holds for all GG-representations VV and all based GG-spaces XX.

Keywords

Cite

@article{arxiv.2508.04421,
  title  = {A genuine equivariant recognition principle for finite groups},
  author = {Branko Juran},
  journal= {arXiv preprint arXiv:2508.04421},
  year   = {2025}
}

Comments

25 pages, comments welcome

R2 v1 2026-07-01T04:37:21.516Z