English

Fixed point sets of smooth $G$-manifolds pseudo-equivalent to a $G$-template

Algebraic Topology 2022-07-18 v1

Abstract

For a finite group GG not of prime power order, Oliver (1996) has answered the question which manifolds occur as the fixed point sets of smooth actions of GG on disks (resp., Euclidean spaces). We extend Oliver's result to compact (resp., open) smooth GG-manifolds MM pseudo-equivalent to YY, a finite Z\mathbb{Z}-acyclic GG-CW complex such that the fixed point set YGY^G is non-empty, connected, and χ(YG)1(modnG)\chi(Y^G) \equiv 1 \pmod{n_G}, where nGn_G is the Oliver number of GG. We prove that the answer to the question above does not depend on the choice of YY. For a finite connected GG-CW complex YY such that YGY^G is non-empty and connected, called a GG-template, we prove that a compact stably parallelizable manifold FF occurs as the fixed point set MGM^G of a compact smooth GG-manifold MM pseudo-equivalent to YY, if and only if χ(F)χ(YG)(modnG)\chi(F) \equiv \chi(Y^G) \pmod{n_G}. Moreover, there exists a compact smooth fixed point free GG-manifold pseudo-equivalent to a GG-template YY, if and only if χ(YG)0(modnG)\chi(Y^G) \equiv 0 \pmod{n_G}. In particular, similarly as for actions on disks, there exists a compact smooth fixed point free GG-manifold pseudo-equivalent to the real projective space RP2n\mathbb{R}{\rm P}^{2n} for an integer n1n \geq 1, if and only if GG is an Oliver group. Finally, we prove that each finite Oliver group GG has a smooth fixed point free action on RP2n\mathbb{R}{\rm P}^{2n} itself for some integer n1n \geq 1.

Keywords

Cite

@article{arxiv.2207.07404,
  title  = {Fixed point sets of smooth $G$-manifolds pseudo-equivalent to a $G$-template},
  author = {Krzysztof M. Pawałowski and Jan Pulikowski},
  journal= {arXiv preprint arXiv:2207.07404},
  year   = {2022}
}