English

Contactomorphism groups and Legendrian flexibility

Symplectic Geometry 2019-02-01 v2 Geometric Topology

Abstract

We explain a connection between the algebraic and geometric properties of groups of contact transformations, open book decompositions, and flexible Legendrian embeddings. The main result is that, if a closed contact manifold (V,ξ)(V, \xi) has a supporting open book whose pages are flexible Weinstein manifolds, then the connected component GG of the identity in its automorphism group is a uniformly simple group: for every non-trivial element gg, every other element is a product of at most 128(dimV+1)128(\dim V + 1) conjugates of g±1g^{\pm 1}. In particular any conjugation invariant norm on this group is bounded. We also prove the later statement still holds for the universal cover of GG.

Keywords

Cite

@article{arxiv.1803.07997,
  title  = {Contactomorphism groups and Legendrian flexibility},
  author = {Sylvain Courte and Patrick Massot},
  journal= {arXiv preprint arXiv:1803.07997},
  year   = {2019}
}

Comments

38 pages, 5 figures v2: corrects one silly mistake, updates references and acknowledgments. Submitted version

R2 v1 2026-06-23T01:00:36.619Z