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For any Legendrian link in $\displaystyle \mathbb{R}^{3}$ given by the rainbow closure of a positive braid word, we develop an explicit and computable description of a Legendrian isotopy invariant associated with it, namely the…

Symplectic Geometry · Mathematics 2025-11-20 Ángel Rodríguez--López

In this short note, we provide a criterion for DGA-homotopy of augmentations of Chekanov-Eliashberg algebra of disconnected Legendrian submanifolds. We apply the criterion to obtain the extension of geography results of Bourgeois and Galant…

Symplectic Geometry · Mathematics 2022-10-12 Filip Strakoš

Let $\Lambda$ be a Legendrian in the jet space of some manifold $X$. To a generating family presentation of $\Lambda$, we associate a constructible sheaf on $X \times \mathbb{R}$ whose singular support at infinity is $\Lambda$, and such…

Symplectic Geometry · Mathematics 2018-09-11 Vivek Shende

This is the third in a series of papers in which we construct Chekanov-Eliashberg algebras for Legendrians in circle-fibered contact manifolds and study the associated augmentation varieties. In this part, we prove that for connected…

Symplectic Geometry · Mathematics 2026-05-14 Kenneth Blakey , Soham Chanda , Yuhan Sun , Chris T. Woodward

We define ruling invariants for even-valence Legendrian graphs in standard contact three-space. We prove that rulings exist if and only if the DGA of the graph, introduced by the first two authors, has an augmentation. We set up the usual…

Symplectic Geometry · Mathematics 2019-11-21 Byung Hee An , Youngjin Bae , Tamás Kálmán

We define an SFT-type invariant for Legendrian knots in the standard contact $\mathbb{R}^3$. The invariant is a deformation of the Chekanov-Eliashberg differential graded algebra. The differential consists of a part that counts index zero…

Symplectic Geometry · Mathematics 2024-09-10 Milica Dukic

Given a Legendrian link in $\#^k(S^1\times S^2)$, we extend the definition of a normal ruling from $J^1(S^1)$ given by Lavrov and Rutherford and show that the existence of an augmentation to any field of the Chekanov-Eliashberg differential…

Symplectic Geometry · Mathematics 2017-06-14 Caitlin Leverson

We define a differential graded algebra associated to Legendrian knots in thickened convex surfaces $\Sigma\times \mathbb{R}$. The algebra is defined in the same spirit as the Chekanov-Eliashberg DGA for Legendrians in $\mathbb{R}^3$, but…

Symplectic Geometry · Mathematics 2026-05-14 Nancy Mae Eagles , Zijian Rong

We classify topologically trivial Legendrian $\Theta$-graphs and identify the complete family of nondestabilizeable Legendrian realizations in this topological class. In contrast to all known results for Legendrian knots, this is an…

Geometric Topology · Mathematics 2016-06-03 Peter Lambert-Cole , Danielle O'Donnol

Associated to Legendrian links in the standard contact three-space, Ruling polynomials are Legendrian isotopy invariants, which also compute augmentation numbers, that is, the points-counting of augmentation varieties for Legendrian links…

Symplectic Geometry · Mathematics 2017-07-18 Tao Su

The Cheeger constant of a graph, or equivalently its coboundary expansion, quantifies the expansion of the graph. This notion assumes an implicit choice of a coefficient group, namely, $\mathbb{F}_2$. In this paper, we study Cheeger-type…

Combinatorics · Mathematics 2025-04-29 Uriya A. First , Tali Kaufman

This paper presents an algorithm to deform any Legendrian singularity to a nearby Legendrian subvariety with singularities of a simple combinatorial nature. Furthermore, the category of microlocal sheaves on the original Legendrian…

Symplectic Geometry · Mathematics 2016-10-07 David Nadler

We strengthen the link between holomorphic and generating-function invariants of Legendrian knots by establishing a formula relating the number of augmentations of a knot's contact homology to the complete ruling invariant of Chekanov and…

Symplectic Geometry · Mathematics 2016-09-07 Lenhard L. Ng , Joshua M. Sabloff

To a Legendrian knot, one can associate an $\mathcal{A}_{\infty}$ category, the augmentation category. An exact Lagrangian cobordism between two Legendrian knots gives a functor of the augmentation categories of the two knots. We study the…

Symplectic Geometry · Mathematics 2018-03-16 Yu Pan

We study satellites of Legendrian knots in R^3 and their relation to the Chekanov-Eliashberg differential graded algebra of the knot. In particular, we generalize the well-known correspondence between rulings of a Legendrian knot in R^3 and…

Symplectic Geometry · Mathematics 2013-08-13 Lenhard Ng , Dan Rutherford

We study augmentations of a Legendrian surface $L$ in the $1$-jet space, $J^1M$, of a surface $M$. We introduce two types of algebraic/combinatorial structures related to the front projection of $L$ that we call chain homotopy diagrams…

Symplectic Geometry · Mathematics 2018-04-11 Dan Rutherford , Michael G Sullivan

For a Legendrian link $\Lambda \subset J^1M$ with $M = \mathbb{R}$ or $S^1$, immersed exact Lagrangian fillings $L \subset \mbox{Symp}(J^1M) \cong T^*(\mathbb{R}_{>0} \times M)$ of $\Lambda$ can be lifted to conical Legendrian fillings…

Symplectic Geometry · Mathematics 2023-01-23 Yu Pan , Dan Rutherford

The Chekanov-Eliashberg dg-algebra is a holomorphic curve invariant associated to Legendrian submanifolds of a contact manifold. We extend the definition to Legendrian embeddings of skeleta of Weinstein manifolds. Via Legendrian surgery,…

Symplectic Geometry · Mathematics 2023-03-02 Johan Asplund , Tobias Ekholm

A connection between holomorphic and generating family invariants of Legendrian knots is established; namely, that the existence of a ruling (or decomposition) of a Legendrian knot is equivalent to the existence of an augmentation of its…

Symplectic Geometry · Mathematics 2007-05-23 Joshua M. Sabloff

Any link that is the closure of a positive braid has a natural Legendrian representative. These were introduced in an earlier paper, where their Chekanov--Eliashberg contact homology was also evaluated. In this paper we re-phrase and…

Symplectic Geometry · Mathematics 2007-05-23 Tamás Kálmán