English

Formality of Floer complex of the ideal boundary of hyperbolic knot complement

Symplectic Geometry 2019-03-12 v2 Geometric Topology

Abstract

This is a sequel to the authors' article [BKO](arXiv:1901.02239). We consider a hyperbolic knot KK in a closed 3-manifold MM and the cotangent bundle of its complement MKM \setminus K. We equip MKM \setminus K with a hyperbolic metric hh and its cotangent bundle T(MK)T^*(M \setminus K) with the induced kinetic energy Hamiltonian Hh=12ph2H_h = \frac{1}{2} |p|_h^2 and Sasakian almost complex structure JhJ_h, and associate a wrapped Fukaya category to T(MK)T^*(M\setminus K) whose wrapping is given by HhH_h. We then consider the conormal νT\nu^*T of a horo-torus TT as its object. We prove that all non-constant Hamiltonian chords are transversal and of Morse index 0 relative to the horo-torus TT, and so that the structure maps satisfy m~k=0\widetilde{\mathfrak m}^k = 0 unless k2k \neq 2 and an AA_\infty-algebra associated to νT\nu^*T is reduced to a noncommutative algebra concentrated to degree 0. We prove that the wrapped Floer cohomology HW(νT;Hh)HW(\nu^*T; H_h) with respect to HhH_h is well-defined and isomorphic to the Knot Floer cohomology HW((MK))HW(\partial_\infty(M \setminus K)) that was introduced in [BKO] for arbitrary knot KMK \subset M. We also define a reduced cohomology, denoted by HW~d((MK))\widetilde{HW}^d(\partial_\infty(M \setminus K)), by modding out constant chords and prove that if HW~d((MK))0\widetilde{HW}^d(\partial_\infty(M \setminus K))\neq 0 for some d1d \geq 1, then KK cannot be hyperbolic. On the other hand, we prove that all torus knots have HW~1((MK))0\widetilde{HW}^1(\partial_\infty(M \setminus K)) \neq 0.

Keywords

Cite

@article{arxiv.1901.02258,
  title  = {Formality of Floer complex of the ideal boundary of hyperbolic knot complement},
  author = {Youngjin Bae and Seonhwa Kim and Yong-Geun Oh},
  journal= {arXiv preprint arXiv:1901.02258},
  year   = {2019}
}

Comments

52 pages, 1 figure; v2 57 pages, 2 figures, calculations for torus knots added, abstract and introduction rewritten, mistakes in the statements and proofs of Proposition 2.1 and Lemma 9.4 corrected, old Section 11 moved to Appendix B, typos corrected