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Let $M$ be a closed manifold. We introduce a family of Legendrian isotopy invariants for Legendrians in $J^1M$, which we collectively call Legendrian higher torsion. Given a choice of a class $\mathcal{F}$ of fibre bundles over $M$,…

Symplectic Geometry · Mathematics 2026-03-31 Daniel Alvarez Gavela , Kiyoshi Igusa , Michael Sullivan

We characterize which Legendrian $4$-plat knots in the standard contact $3$-space have exact orientable Lagrangian fillings. As a corollary, we show that the underlying smooth knot types of fillable Legendrian $4$-plats are positive.

Symplectic Geometry · Mathematics 2017-09-12 Erin R. Lipman , Joshua M. Sabloff

In this note we show that $+1$-contact surgery on distinct Legendrian knots frequently produces contactomorphic manifolds. We also give examples where this happens for $-1$-contact surgery. As an amusing corollary we find overtwisted…

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

We study Lagrangian cobordism groups of oriented surfaces of genus greater than two. We compute the immersed oriented Lagrangian cobordism group of these surfaces. We show that a variant of this group, with relations given by unobstructed…

Symplectic Geometry · Mathematics 2019-01-21 Alexandre Perrier

Let $M_K$ be the 2-fold branched cover of a knot $K in $S^3$. If $H_1(M_K) = {\bf Z}_3 \oplus {\bf Z}_{3^{2i}} \oplus G$ where 3 does not divide the order of $G$ then $K$ is not of order 4 in the concordance group. This obstruction detects…

Geometric Topology · Mathematics 2013-09-30 Charles Livingston , Swatee Naik

Distinct knots K, K' can sometimes share a common p/q-framed Dehn surgery. A folk conjecture held that for a fixed pair of knots, this can occur for at most one value of p/q. We disprove this conjecture by constructing pairs of distinct…

Geometric Topology · Mathematics 2025-06-05 Marc Kegel , Lisa Piccirillo

By a result due to Ziltener, there exist no closed embedded Bohr-Sommerfeld Lagrangians inside $\mathbb CP^n$ for the prequantisation bundle whose total space is the standard contact sphere. On the other hand, any embedded monotone…

Symplectic Geometry · Mathematics 2024-12-16 Georgios Dimitroglou Rizell , Roman Golovko

We construct a monotone spin Lagrangian cobordism from L to (L_1, L_2) such that there is no monotone spin Lagrangian cobordism from L to (L_2, L_1), where L, L_1, L_2 are Lagrangians of CP^7.

Symplectic Geometry · Mathematics 2024-11-11 Vardan Oganesyan

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

We prove that all maximal-tb Legendrian torus links (n,m) in the standard contact 3-sphere, except for (2,m),(3,3),(3,4) and (3,5), admit infinitely many Lagrangian fillings in the standard symplectic 4-ball. This is proven by constructing…

Symplectic Geometry · Mathematics 2022-01-14 Roger Casals , Honghao Gao

We present the first examples of elements in the fundamental group of the space of Legendrian links in the standard contact 3-sphere whose action on the Legendrian contact DGA is of infinite order. This allows us to construct the first…

Symplectic Geometry · Mathematics 2022-08-04 Roger Casals , Lenhard Ng

We determine the contact mapping class group of the standard contact structures on lens spaces. To prove the main result, we use the one-parametric convex surface theory to classify Legendrian and transverse rational unknots in any tight…

Geometric Topology · Mathematics 2024-11-26 Hyunki Min

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 introduce topological invariants of knots and braid conjugacy classes, in the form of differential graded algebras, and present an explicit combinatorial formulation for these invariants. The algebras conjecturally give the relative…

Geometric Topology · Mathematics 2014-11-11 Lenhard Ng

We study Legendrian singularities arising in complex contact geometry. We define a one-parameter family of bases in the ring of Legendrian characteristic classes such that any Legendrian Thom polynomial has nonnegative coefficients when…

Algebraic Geometry · Mathematics 2011-12-08 Malgorzata Mikosz , Piotr Pragacz , Andrzej Weber

We classify the Legendrian torus knots in S^1\times S^2 with its standard tight contact structure up to Legendrian isotopy.

Geometric Topology · Mathematics 2013-10-08 Feifei Chen , Fan Ding , Youlin Li

In this paper, we construct the first families of distinct Lagrangian ribbon disks in the standard symplectic 4-ball which have the same boundary Legendrian knots, and are not smoothly isotopic or have non-homeomorphic exteriors.

Geometric Topology · Mathematics 2020-10-20 Youlin Li , Motoo Tange

The conormal lift of a link $K$ in $\R^3$ is a Legendrian submanifold $\Lambda_K$ in the unit cotangent bundle $U^* \R^3$ of $\R^3$ with contact structure equal to the kernel of the Liouville form. Knot contact homology, a topological link…

Symplectic Geometry · Mathematics 2014-11-11 Tobias Ekholm , John Etnyre , Lenhard Ng , Michael Sullivan

For $\ell >1$, we develop $L^{(2)}$-signature obstructions for $(4\ell-3)$-dimensional knots with metabelian knot groups to be doubly slice. For each $\ell>1$, we construct an infinite family of knots on which our obstructions are non-zero,…

Geometric Topology · Mathematics 2019-09-19 Patrick Orson , Mark Powell

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