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In this paper, we prove that if two Legendrian knots have isomorphic fundamental GL-racks, then either they have the same Thurston-Bennequin number and the same rotation number, or they have the opposite Thurston-Bennequin numbers and…

Geometric Topology · Mathematics 2025-07-25 Zhiyun Cheng , Zhiyi He

A generalised Legendrian rack is a rack equipped with a Legendrian structure, which is a pair of maps encoding the information of Legendrian Reidemeister moves together with up and down cusps in the front diagram of an oriented Legendrian…

Geometric Topology · Mathematics 2025-10-15 Biswadeep Karmakar , Deepanshi Saraf , Mahender Singh

We define a new algebraic structure called Legendrian racks or racks with Legendrian structure, motivated by the front-projection Reidemeister moves for Legendrian knots. We provide examples of Legendrian racks and use these algebraic…

Geometric Topology · Mathematics 2021-01-26 Jose Ceniceros , Mohamed Elhamdadi , Sam Nelson

In this article, we introduce rack invariants of oriented Legendrian knots in the 3-dimensional Euclidean space endowed with the standard contact structure, which we call Legendrian racks. These invariants form a generalization of the…

Geometric Topology · Mathematics 2017-07-04 Dheeraj Kulkarni , T. V. H. Prathamesh

We study algebraic aspects of generalized Legendrian racks, which are nonassociative structures based on the Legendrian Reidemeister moves. We answer an open question characterizing the group of GL-structures on a given rack. As…

Geometric Topology · Mathematics 2025-07-18 Luc Ta

We study 4-Legendrian racks and their effectiveness at distinguishing Legendrian knots. We prove that permutation racks with 4-Legendrian rack structures cannot distinguish Legendrian knots that share the same knot type, Thurston-Bennequin…

Geometric Topology · Mathematics 2026-03-02 Luc Ta , Peyton Phinehas Wood

We present two different constructions of invariants for Legendrian knots in the standard contact space $\R^3$. These invariants are defined combinatorially, in terms of certain planar projections, and are useful in distinguishing…

Geometric Topology · Mathematics 2007-05-23 Yuri Chekanov

The aim of this paper is to define a homology theory for racks with finite rank N and use it to define invariants of knots generalizing the CJKLS 2-cocycle invariants related to the invariants defined in [15]. For this purpose, we prove…

Geometric Topology · Mathematics 2011-05-24 Mohamed Elhamdadi , Sam Nelson

We study Coxeter racks over $\mathbb{Z}_n$ and the knot and link invariants they define. We exploit the module structure of these racks to enhance the rack counting invariants and give examples showing that these enhanced invariants are…

Geometric Topology · Mathematics 2008-08-13 Sam Nelson , Ryan Wieghard

We give new functions of Legendrian knots derived from Legendrian fronts. These are integer-valued linear functions that are alike the Arnold basic invariant of plane curves. Various generalizations of the Arnold basic invariant have been…

Geometric Topology · Mathematics 2022-06-14 Noboru Ito , Masashi Takamura

In this article we define Lagrangian concordance of Legendrian knots, the analogue of smooth concordance of knots in the Legendrian category. In particular we study the relation of Lagrangian concordance under Legendrian isotopy. The focus…

Symplectic Geometry · Mathematics 2014-10-01 Baptiste Chantraine

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

A (t,s)-rack is a rack structure defined on a module over the ring $\ddot\Lambda=\mathbb{Z}[t^{\pm 1},s]/(s^2-(1-t)s)$. We identify necessary and sufficient conditions for two $(t,s)$-racks to be isomorphic. We define enhancements of the…

Geometric Topology · Mathematics 2011-05-06 Jessica Ceniceros , Sam Nelson

We show that the family of smoothly non-isotopic Legendrian pretzel knots from the work of Cornwell-Ng-Sivek that all have the same Legendrian invariants as the standard unknot have front-spuns that are Legendrian isotopic to the front-spun…

Symplectic Geometry · Mathematics 2026-03-24 Georgios Dimitroglou Rizell , Roman Golovko

We study the unwrapped Fukaya category of Lagrangian branes ending on a Legendrian knot. Our knots live at contact infinity in the cotangent bundle of a surface, the Fukaya category of which is equivalent to the category of constructible…

Symplectic Geometry · Mathematics 2016-11-01 Vivek Shende , David Treumann , Eric Zaslow

We show that for a big class of contact manifolds the groups of order $\leq n$ invariants (with values in an arbitrary Abelian group) of Legendrian, of transverse and of framed knots are canonically isomorphic. On the other hand for an…

Symplectic Geometry · Mathematics 2007-05-23 Vladimir Tchernov

We define ambient isotopy invariants of oriented knots and links using the counting invariants of framed links defined by finite racks. These invariants reduce to the usual quandle counting invariant when the rack in question is a quandle.…

Geometric Topology · Mathematics 2013-07-30 Sam Nelson

We introduce constructions of exact Lagrangian cobordisms with cylindrical Legendrian ends and study their invariants which arise from Symplectic Field Theory. A pair $(X,L)$ consisting of an exact symplectic manifold $X$ and an exact…

Symplectic Geometry · Mathematics 2012-12-27 Tobias Ekholm , Ko Honda , Tamás Kálmán

Each ruling of a Legendrian link can be naturally treated as a surface. For knots, the ruling is 2-graded if and only if the surface is orientable. For 2-graded rulings of homogeneous (in particular, alternating) knots, we prove that the…

Geometric Topology · Mathematics 2007-11-26 Tamás Kálmán

Biracks are algebraic structures related to knots and links. We define a new enhancement of the birack counting invariant for oriented classical and virtual knots and links via algebraic structures called birack dynamical cocycles. The new…

Geometric Topology · Mathematics 2012-05-22 Sam Nelson , Emily Watterberg
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