English

Foliation de Rham cohomology of generic Reeb foliations

Symplectic Geometry 2025-05-13 v2

Abstract

In this paper, we prove that there exists a residual subset of contact forms λ\lambda (if any) on a compact connected orientable manifold MM for which the foliation de Rham cohomology of the associated Reeb foliation FλF_\lambda is trivial in that both H0(Fλ,R)H^0(F_\lambda,{\mathbb R}) and H1(Fλ,R)H^1(F_\lambda,{\mathbb R}) are isomorphic to R\mathbb R. We also prove the same triviality for a generic choice of contact forms with fixed contact structure ξ\xi. For any choice of λ\lambda from the aforementioned residual subset, this cohomological result can be restated as any of the following two equivalent statements: (1) The functional equation Rλ[f]=uR_{\lambda}[f] = u is uniquely solvable (modulo the addition by constant) for any uu satisfying Mudμλ=0\int_M u\, d\mu_\lambda =0, or (2) The Lie algebra of the group of strict contactomorphisms is isomorphic to the span of Reeb vector fields, and so isomorphic to the 1 dimensional abelian Lie algebra R\mathbb R. This result is also a key ingredient for the proof of the generic scarcity result of strict contactomorphisms by Savelyev and the author.

Keywords

Cite

@article{arxiv.2504.16453,
  title  = {Foliation de Rham cohomology of generic Reeb foliations},
  author = {Yong-Geun Oh},
  journal= {arXiv preprint arXiv:2504.16453},
  year   = {2025}
}

Comments

37 pages, comments welcome! v2) 55 pages, the case with fixed contact structure added, new perspective on contact dynamics added, exposition much improved