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We study the behavior of Legendrian and transverse knots under the operation of connected sums. As a consequence we show that there exist Legendrian knots that are not distinguished by any known invariant. Moreover, we classify Legendrian…

Symplectic Geometry · Mathematics 2007-05-23 John B. Etnyre , Ko Honda

In the present paper a criteria for a rectangular diagram to admit a simplification is given in terms of Legendrian knots. It is shown that there are two types of simplifications which are mutually independent in a sense. A new proof of the…

Geometric Topology · Mathematics 2013-10-22 Ivan Dynnikov , Maxim Prasolov

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

In this article we give necessary and sufficient conditions for two triples of integers to be realized as the Thurston-Bennequin number and the rotation number of a Legendrian theta-graph with all cycles unknotted. We show that these…

Geometric Topology · Mathematics 2016-01-20 Danielle O'Donnol , Elena Pavelescu

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

All knots in $R^3$ possess Seifert surfaces, and so the classical Thurston-Bennequin and rotation (or Maslov) invariants for Legendrian knots in a contact structure on $R^3$ can be defined. The definitions extend easily to null-homologous…

Geometric Topology · Mathematics 2015-02-27 Paul A. Schweitzer SJ , Fábio S. Souza

We give explicit formulas and algorithms for the computation of the Thurston-Bennequin invariant of a nullhomologous Legendrian knot on a page of a contact open book and on contact Heegaard surfaces. Furthermore, we extend the results to…

Geometric Topology · Mathematics 2026-02-10 Sebastian Durst , Marc Kegel , Mirko Klukas

We establish a relation between several easy-to-calculate numerical invariants of generic knots in $\mathbb{H}^2 \times S^1$, and use it to give a new method of computing the Thurston-Bennequin number of Legendrian knots in the tight…

Geometric Topology · Mathematics 2007-05-23 Hao Wu

Relative self-linking and linking "numbers" for pairs of knots in oriented 3-manifolds are defined in terms of intersection invariants of immersed surfaces in 4-manifolds. The resulting concordance invariants generalize the usual…

Geometric Topology · Mathematics 2014-10-01 Rob Schneiderman

We construct a combinatorial invariant of Legendrian knots in standard contact three-space. This invariant, which encodes rational relative Symplectic Field Theory and extends contact homology, counts holomorphic disks with an arbitrary…

Symplectic Geometry · Mathematics 2015-05-13 Lenhard Ng

We give an explicit formula to compute the rotation number of a nullhomologous Legendrian knot in contact (1/n)-surgery diagrams along Legendrian links and obtain a corresponding result for the self-linking number of transverse knots.…

Geometric Topology · Mathematics 2017-09-01 Sebastian Durst , Marc Kegel

In this article, we consider the maximal value of the Thurston--Bennequin invariant of Legendrian knots which topologically represent a fixed knot type in the standard contact 3-space and we prove a formula of the value under the connected…

Geometric Topology · Mathematics 2007-05-23 Ichiro Torisu

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

The problem of classification of Legendrian knots (links) up to isotopy in the class of Legendrian embeddings (Legendrian isotopy) naturally leads to the following two subproblems. The first of them is: which combinations of the three…

Geometric Topology · Mathematics 2016-09-07 Yuri Chekanov

We establish an upper bound for the Thurston-Bennequin number of a Legendrian link using the Khovanov homology of the underlying topological link. This bound is sharp in particular for all alternating links, and knots with nine or fewer…

Geometric Topology · Mathematics 2014-10-01 Lenhard Ng

It is proved in this note that the analogues of the Bennequin inequality which provide an upper bound for the Bennequin invariant of a Legendrian knot in the standard contact three dimensional space in terms of the lower degree in the…

Geometric Topology · Mathematics 2007-05-23 Emmanuel Ferrand

We prove that two Legendrian knots in a contact structure which is trivializable as a plane bundle are Legendrian isotopic provided that (1) they are isotopic as framed knots, (2) they have the same rotation number with respect to some…

Geometric Topology · Mathematics 2007-05-23 Katarzyna Dymara

We study Legendrian and transverse realizations of the negative torus knots $T_{(p,-q)}$ in all contact structures on the $3$-sphere. We give a complete classification of the strongly non-loose transverse realizations and the strongly…

Geometric Topology · Mathematics 2023-03-02 Irena Matkovič

We classify Legendrian rational unknots with tight complements in the lens spaces L(p,1) up to coarse equivalence. As an example of the general case, this classification is also worked out for L(5,2). The knots are described explicitly in a…

Symplectic Geometry · Mathematics 2018-03-22 Hansjörg Geiges , Sinem Onaran

It is well-known that a knot in a contact manifold $(M,C)$ transverse to a trivialized contact structure possesses the natural framing given by the first of the trivialization vectors along the knot. If the Euler class $e_C\in H^2(M)$ of…

Symplectic Geometry · Mathematics 2007-05-23 Vladimir Chernov