scholarly journals Contact structures and reducible surgeries

2015 ◽  
Vol 152 (1) ◽  
pp. 152-186 ◽  
Author(s):  
Tye Lidman ◽  
Steven Sivek
Keyword(s):  
Contact Structures ◽  
Surgery Theory ◽  
Contact Topology ◽  
Exceptional Surgery ◽  
Genus 2 ◽  
Cabling Conjecture

We apply results from both contact topology and exceptional surgery theory to study when Legendrian surgery on a knot yields a reducible manifold. As an application, we show that a reducible surgery on a non-cabled positive knot of genus$g$must have slope$2g-1$, leading to a proof of the cabling conjecture for positive knots of genus 2. Our techniques also produce bounds on the maximum Thurston–Bennequin numbers of cables.

scholarly journals The diffeotopy group of S1×S2 via contact topology

2010 ◽  
Vol 146 (4) ◽  
pp. 1096-1112 ◽  
Author(s):  
Fan Ding ◽  
Hansjörg Geiges
Keyword(s):  
Fundamental Group ◽  
Rotation Number ◽  
Contact Structure ◽  
Alternative Proof ◽  
Contact Structures ◽  
Legendrian Knots ◽  
Contact Topology ◽  
Tight Contact ◽  
Contact Surgery

AbstractAs shown by Gluck in 1962, the diffeotopy group of S1×S2 is isomorphic to ℤ2⊕ℤ2 ⊕ℤ2. Here an alternative proof of this result is given, relying on contact topology. We then discuss two applications to contact topology: (i) it is shown that the fundamental group of the space of contact structures on S1×S2, based at the standard tight contact structure, is isomorphic to ℤ; (ii) inspired by previous work of Fraser, an example is given of an integer family of Legendrian knots in S1×S2#S1×S2 (with its standard tight contact structure) that can be distinguished with the help of contact surgery, but not by the classical invariants (topological knot type, Thurston–Bennequin invariant, and rotation number).

scholarly journals Special moves for open book decompositions of 3-manifolds

2018 ◽  
Vol 27 (11) ◽  
pp. 1843008
Author(s):  
Riccardo Piergallini ◽  
Daniele Zuddas
Keyword(s):  
Equivalence Theorem ◽  
Contact Structures ◽  
Local Version ◽  
Open Book ◽  
Lefschetz Fibrations ◽  
3 Dimensional ◽  
Contact Topology ◽  
Open Book Decompositions ◽  
Stable Equivalence ◽  
Complete Set

We provide a complete set of two moves that suffice to relate any two open book decompositions of a given 3-manifold. One of the moves is the usual plumbing with a positive or negative Hopf band, while the other one is a special local version of Harer’s twisting, which is presented in two different (but stably equivalent) forms. Our approach relies on 4-dimensional Lefschetz fibrations, and on 3-dimensional contact topology, via the Giroux-Goodman stable equivalence theorem for open book decompositions representing homologous contact structures.

scholarly journals Brieskorn manifolds, positive Sasakian geometry, and contact topology

2016 ◽  
Vol 28 (5) ◽  
pp. 943-965
Author(s):  
Charles P. Boyer ◽  
Leonardo Macarini ◽  
Otto van Koert
Keyword(s):  
Moduli Space ◽  
Einstein Metrics ◽  
Contact Structures ◽  
Rational Homology ◽  
Contact Topology ◽  
Connected Sums ◽  
New Family ◽  
Rational Homology Spheres ◽  
Sasakian Geometry ◽  
Sasakian Structures

AbstractUsing ${S^{1}}$-equivariant symplectic homology, in particular its mean Euler characteristic, of the natural filling of links of Brieskorn–Pham polynomials, we prove the existence of infinitely many inequivalent contact structures on various manifolds, including in dimension 5 the k-fold connected sums of ${S^{2}\times S^{3}}$ and certain rational homology spheres. We then apply our result to show that on these manifolds the moduli space of classes of positive Sasakian structures has infinitely many components. We also apply our results to give lower bounds on the number of components of the moduli space of Sasaki–Einstein metrics on certain homotopy spheres. Finally, a new family of Sasaki–Einstein metrics of real dimension 20 on ${S^{5}}$ is exhibited.

Autonomous Geometrical Mechanics

2018 ◽  
Author(s):  
Peter Mann
Keyword(s):  
Phase Space ◽  
Contact Structure ◽  
Invariant Tori ◽  
Time Dependent ◽  
Contact Structures ◽  
Natural Setting ◽  
Adiabatic Invariance ◽  
Jet Bundle ◽  
Integrability Theorem ◽  
Extended Phase

This chapter examines the structure of the phase space of an integrable system as being constructed from invariant tori using the Arnold–Liouville integrability theorem, and periodic flow and ergodic flow are investigated using action-angle theory. Time-dependent mechanics is formulated by extending the symplectic structure to a contact structure in an extended phase space before it is shown that mechanics has a natural setting on a jet bundle. The chapter then describes phase space of integrable systems and how tori behave when time-dependent dynamics occurs. Adiabatic invariance is discussed, as well as slow and fast Hamiltonian systems, the Hannay angle and counter adiabatic terms. In addition, the chapter discusses foliation, resonant tori, non-resonant tori, contact structures, Pfaffian forms, jet manifolds and Stokes’s theorem.

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