English

Equivariant formality in complex-oriented theories

Symplectic Geometry 2024-05-24 v2 Algebraic Geometry Algebraic Topology

Abstract

Let GG be a product of unitary groups and let (M,ω)(M,\omega) be a compact symplectic manifold with Hamiltonian GG-action. We prove an equivariant formality result for any complex-oriented cohomology theory E\mathbb{E}^* (in particular, integral cohomology). This generalizes the celebrated result of Atiyah-Bott-Kirwan for rational cohomology from the 1980s. The proof does not use classical ideas but instead relies on a recent cohomological splitting result of Abouzaid-McLean-Smith for Hamiltonian fibrations over CP1.\mathbb{CP}^1. Moreover, we establish analogues of the "localization" and "injectivity to fixed points" theorems for certain cohomology theories studied by Hopkins-Kuhn-Ravenel. As an application of these results, we establish a Goresky-Kottwitz-MacPherson theorem with Morava KK-theory coefficients for Hamiltonian TT-manifolds.

Keywords

Cite

@article{arxiv.2405.05821,
  title  = {Equivariant formality in complex-oriented theories},
  author = {Shaoyun Bai and Daniel Pomerleano},
  journal= {arXiv preprint arXiv:2405.05821},
  year   = {2024}
}

Comments

14 pages, comments are welcome! v2: minor updates

R2 v1 2026-06-28T16:22:13.877Z