English

Proper affine actions: a sufficient criterion

Group Theory 2024-02-28 v5

Abstract

For a semisimple real Lie group GG with an irreducible representation ρ\rho on a finite-dimensional real vector space VV, we give a sufficient criterion on ρ\rho for existence of a group of affine transformations of VV whose linear part is Zariski-dense in ρ(G)\rho(G) and that is free, nonabelian and acts properly discontinuously on VV. This new criterion is more general than the one given in the author's previous paper "Proper affine actions in non-swinging representations" (submitted; available at arXiv:1605.03833), insofar as it also deals with "swinging" representations. We conjecture that it is actually a necessary and sufficient criterion, applicable to all representations.

Keywords

Cite

@article{arxiv.1612.08942,
  title  = {Proper affine actions: a sufficient criterion},
  author = {Ilia Smilga},
  journal= {arXiv preprint arXiv:1612.08942},
  year   = {2024}
}

Comments

This paper generalizes the author's previous papers arXiv:1406.5906 and arXiv:1605.03833 . The structure of the proof is similar; a few passages are borrowed from the earlier papers. In this version, I corrected a mathematical mistake in Definition 6.12.(iii). This mistake remains present in the published version; an erratum has been published to address it

R2 v1 2026-06-22T17:36:08.564Z