English

Ruling polynomials and augmentations over finite fields

Symplectic Geometry 2017-05-17 v2 Geometric Topology

Abstract

For any Legendrian link, L, in (\R^3, \ker(dz-y\,dx)) we define invariants, Aug_m(L,q), as normalized counts of augmentations from the Legendrian contact homology DGA of L into a finite field of order q where the parameter m is a divisor of twice the rotation number of L. Generalizing a result of Ng and Sabloff for the case q =2, we show the augmentation numbers, Aug_m(L,q), are determined by specializing the m-graded ruling polynomial, R^m_L(z), at z = q^{1/2}-q^{-1/2}. As a corollary, we deduce that the ruling polynomials are determined by the Legendrian contact homology DGA.

Keywords

Cite

@article{arxiv.1308.4662,
  title  = {Ruling polynomials and augmentations over finite fields},
  author = {Michael B. Henry and Dan Rutherford},
  journal= {arXiv preprint arXiv:1308.4662},
  year   = {2017}
}

Comments

31 pages, 19 figures; v2. Exposition improved, citations added, proof of Prop. 3.6 simplified; to appear in Journal of Topology

R2 v1 2026-06-22T01:12:55.850Z