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Ko Honda

Publications and source records attributed to Ko Honda.

54 records · Page 3Linked to original sources
arXiv2005

Constructions controlees de champs de Reeb et applications

On every compact, orientable, irreducible 3-manifold V which is toroidal or has torus boundary components we construct a contact 1-form whose Reeb vector field R does not have any contractible periodic orbits and is tangent to the boundary. Moreover, if bdry V is nonempty, then the Reeb vector field R is transverse to a taut foliation. By appealing to results of Hofer, Wysocki, and Zehnder, we show that, under certain conditions, the 3-manifold obtained by Dehn filling along bdry V is irreducible and different from the 3-sphere. Resumé On construit, sur toute variete V de dimension trois orientable, compacte, irreductible, bordee par des tores ou toroidale, une forme de contact dont le champ de Reeb R est sans orbite periodique contractible et tangent au bord. De plus, si le bord de V est non vide, le champ R est transversal a un feuilletage tendu. En utilisant des resultats de Hofer, Wysocki et Zehnder, on obtient sous certaines conditions que la variete obtenue par obturation de Dehn le long du bord de V est irreductible et differente de la sphere S^3.

math.GT↗
arXiv2005

Right-veering diffeomorphisms of compact surfaces with boundary I

We initiate the study of the monoid of right-veering diffeomorphisms on a compact oriented surface with nonempty boundary. The monoid strictly contains the monoid of products of positive Dehn twists. We explain the relationship to tight contact structures and open book decompositions.

math.GT↗
arXiv2005

Pinwheels and bypasses

We give a necessary and sufficient condition for the addition of a collection of disjoint bypasses to a convex surface to be universally tight -- namely the nonexistence of a polygonal region which we call a virtual pinwheel.

math.GT↗
arXiv2003

Notes on the isotopy finiteness

This is the less official, English version of the proof of the fact that every closed atoroidal 3-manifold carries finitely many isotopy classes of tight contact structures.

math.GT↗
arXiv2003

On the coarse classification of tight contact structures

We present a sketch of the proof of the following theorems: (1) Every 3-manifold has only finitely many homotopy classes of 2-plane fields which carry tight contact structures. (2) Every closed atoroidal 3-manifold carries finitely many isotopy classes of tight contact structures.

math.GT↗
arXiv2002

Knots and Contact Geometry II: Connected Sums

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 knots in some non-Legendrian simple knot types.

math.SG↗
arXiv2001

On the classification of tight contact structures I

We develop new techniques in the theory of convex surfaces to prove complete classification results for tight contact structures on lens spaces, solid tori, and T^2 X I. Erratum: In this note we seek to remedy errors which appeared in version 2 and were propagated in subsequent papers.

math.DG↗
arXiv2001

On the Gabai-Eliashberg-Thurston theorem

We present a new, completely three-dimensional proof of the fact, due to Gabai-Eliashberg-Thurston, that every closed, oriented, irreducible 3-manifold with nonzero second homology carries a universally tight contact structure.

math.GT↗
arXiv2001

Tight contact structures on fibered hyperbolic 3-manifolds

We take a first step towards understanding the relationship between foliations and universally tight contact structures on hyperbolic 3-manifolds. If a surface bundle over a circle has pseudo-Anosov holonomy, we obtain a classification of "extremal" tight contact structures. Specifically, there is exactly one contact structure whose Euler class, when evaluated on the fiber, equals the Euler number of the fiber. This rigidity theorem is a consequence of properties of the action of pseudo-Anosov maps on the complex of curves of the fiber and a remarkable flexibility property of convex surfaces in such a space. Indeed this flexibility may be seen in surface bundles over an interval where the analogous classification theorem is also established.

math.GT↗
arXiv2001

On Symplectic Cobordisms

In this note we make several observations concerning symplectic cobordisms. Among other things we show that every contact 3-manifold has infinitely many concave symplectic fillings and that all overtwisted contact 3-manifolds are ``symplectic cobordism equivalent.''

math.SG↗
arXiv2001

Gluing tight contact structures

We prove gluing theorems for tight contact structures. In particular, we rederive (as special cases) gluing theorems due to Colin and Makar-Limanov, and present an algorithm for determining whether a given contact structure on a handlebody is tight. As applications, we construct a tight contact structure on a genus 4 handlebody which becomes overtwisted after Legendrian -1 surgery, and study certain Legendrian surgeries on T^3.

math.GT↗
arXiv2001

Convex decomposition theory

We use convex decomposition theory to (1) reprove the existence of a universally tight contact structure on every irreducible 3-manifold with nonempty boundary, and (2) prove that every toroidal 3-manifold carries infinitely many nonisotopic, nonisomorphic tight contact structures.

math.GT↗
arXiv2000

Tight contact structures and taut foliations

We show the equivalence of several notions in the theory of taut foliations and the theory of tight contact structures. We prove equivalence, in certain cases, of existence of tight contact structures and taut foliations.

math.GT↗
arXiv2000

Knots and Contact Geometry

We classify Legendrian torus knots and figure eight knots in the tight contact structure on the 3-sphere up to Legendrian isotopy. As a corollary to this we also obtain the classification of transversal torus knots and figure eight knots up to transversal isotopy.

math.GT↗
arXiv1997

Local Properties of Self-Dual Harmonic 2-forms on a 4-Manifold

We will prove a Moser-type theorem for self-dual harmonic 2-forms on closed 4-manifolds, and use it to classify local forms on neighborhoods of singular circles on which the 2-form vanishes. Removing neighborhoods of the circles, we obtain a symplectic manifold with contact boundary - we show that the contact form on each S^1\times S^2, after a slight modification, must be one of two possibilities.

dg-ga↗