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Lenhard Lee Ng

Professor of Mathematics
Mathematics
216 Physics Building, Box 90320, Durham, NC 27708-0320
120 Science Drive, Durham, NC 27708

Selected Publications


Frontiers in Geometry and Topology

Book · July 19, 2024 This volume contains the proceedings of the summer school and research conference “Frontiers in Geometry and Topology”, celebrating the sixtieth birthday of Tomasz Mrowka, which was held from August 1–12, 2022, at the Abdus Salam ... ... Cite

Torsion in linearized contact homology for Legendrian knots

Journal Article · August 25, 2023 We present examples of Legendrian knots in R3 that have linearized Legendrian contact homology over Z containing torsion. As a consequence, we show that there exist augmentations of Legendrian knots over Z that are not ind ... Link to item Cite

Braid loops with infinite monodromy on the Legendrian contact DGA

Journal Article Journal of Topology · December 1, 2022 We present the first examples of elements in the fundamental group of the space of Legendrian links in (Formula presented.) whose action on the Legendrian contact DGA is of infinite order. This allows us to construct the first families of Legendrian links ... Full text Open Access Cite

Augmentations are sheaves

Journal Article Geometry and Topology · January 1, 2020 Full text Open Access Cite

Higher genus knot contact homology and recursion for colored HOMFLY-PT polynomials

Journal Article ADVANCES IN THEORETICAL AND MATHEMATICAL PHYSICS · 2020 Open Access Cite

Higher genus knot contact homology and recursion for colored HOMFLY-PT polynomials

Journal Article Advances in Theoretical and Mathematical Physics · January 1, 2020 We sketch a construction of Legendrian Symplectic Field Theory (SFT) for conormal tori of knots and links. Using large N duality and Witten’s connection between open Gromov–Witten invariants and Chern–Simons gauge theory, we relate the SFT of a link conorm ... Full text Open Access Cite

Legendrian contact homology in R3

Journal Article Surveys in Differential Geometry · 2020 Full text Cite

Representations, sheaves and Legendrian (2,m) torus links

Journal Article JOURNAL OF THE LONDON MATHEMATICAL SOCIETY-SECOND SERIES · August 1, 2019 Full text Open Access Link to item Cite

A complete knot invariant from contact homology

Journal Article Inventiones Mathematicae · March 1, 2018 We construct an enhanced version of knot contact homology, and show that we can deduce from it the group ring of the knot group together with the peripheral subgroup. In particular, it completely determines a knot up to smooth isotopy. The enhancement cons ... Full text Open Access Cite

Problems and solutions

Journal Article American Mathematical Monthly · January 1, 2018 Full text Cite

Problems and solutions

Journal Article American Mathematical Monthly · December 1, 2017 Full text Cite

Problems and solutions

Journal Article American Mathematical Monthly · October 1, 2017 Full text Cite

Problems and solutions

Journal Article American Mathematical Monthly · May 1, 2017 Full text Cite

Knot contact homology, string topology, and the cord algebra

Journal Article Journal de l'Ecole Polytechnique - Mathematiques · January 1, 2017 The conormal Lagrangian LK of a knot K in R3 is the submanifold of the cotangent bundle T∗R3 consisting of covectors along K that annihilate tangent vectors to K. By intersecting with the unit cotangent bundle S∗R3, one obtains the unit conormal ΛK, and th ... Full text Open Access Cite

Problems and Solutions

Journal Article The American Mathematical Monthly · 2017 Full text Cite

Obstructions to Lagrangian concordance

Journal Article Algebraic & Geometric Topology · April 26, 2016 Full text Open Access Cite

On transverse invariants from Khovanov homology

Journal Article Quantum Topology · September 9, 2015 In [31], O. Plamenevskaya associated to each transverse knot K an element of the Khovanov homology of K. In this paper, we give two re_nements of Plamenevskaya’s invariant, one valued in Bar-Natan’s deformation (from [2]) of the Khovanov complex and anothe ... Full text Open Access Cite

Legendrian contact homology in the boundary of a subcritical weinstein 4-Manifold

Journal Article Journal of Differential Geometry · September 1, 2015 We give a combinatorial description of the Legendrian contact homology algebra associated to a Legendrian link in S1 × S2 or any connected sum #k(S1 ×S2), viewed as the contact boundary of the Weinstein manifold obtained by attaching 1-handles to the 4-bal ... Full text Open Access Cite