The SGGTC seminar meets on Fridays in Math 417, at 10:45 am unless noted otherwise.

Previous semesters: Fall 2010, Spring 2010, Fall 2009, Spring 2009, Fall 2008, Spring 2008, Fall 2007.

Other area seminars and conferences. Our e-mail list.

SGGTC Seminar Schedule

Date Speaker Title
Jan 21 Organizational Meeting
Math 520, 1:20 pm
Organizational Meeting
with Geometric Topology Seminar
Jan 21 Jen Hom
(University of Pennsylvania)
Concordance and the knot Floer complex
Jan 28 Penka Georgieva
(Stanford University)
Open Gromov-Witten disk invariants
Feb 4 Pierre Schapira
(Institut de Mathématiques de Jussieu)
Sheaf quantization of Hamiltonian isotopies and applications
Feb 11 Chris Woodward
Behavior of Gromov-Witten invariants under birational transformations of git type
Feb 18 No seminar this week.
Feb 25 James Pascaleff
Floer cohomology in the mirror of CP^2 relative to a conic and a line
Mar 4 Bulent Tosun
(Georgia Tech)
Legendrian and transverse knots in cabled knot types
Mar 11 Thomas Kragh
Fibration properties of symplectic homology and the Nearby Lagrangian conjecture
Mar 18 Spring break. No seminar this week.
Mar 25 Alexandra Popa
(Stony Brook)
On Mirror Formulas in Open and Closed Gromov-Witten Theory
Apr 1 Yanki Lekili
Fukaya categories of the torus and Dehn surgery
There are two talks on April 8!
Apr 8
Mohammed Abouzaid
On Homological Mirror Symmetry for Toric varieties
Apr 8
Dan Rutherford
A combinatorial Legendrian knot DGA from generating families
Apr 15 Frol Zapolsky
On the Hofer geometry on the space of Lagrangians
There are two talks on April 22!
Apr 22
Chris Schommer-Pries
The Structure of Fusion Categories via Topological Quantum Field Theories
Apr 22
Yongbin Ruan
(University of Michigan)
Gromov-Witten theory of elliptic orbifold P^1 and quasi-modular form
Apr 29 Tye Lidman
Heegaard Floer Homology and Triple Cup Products
May 6 No seminar this week.
May 13 David Treumann
Constructible sheaves, plumbings, and homological mirror symmetry



January 21, 2011

Organizational Meeting

with Geometric Topology Seminar

January 21, 2011

Jen Hom, "Concordance and the knot Floer complex"

Abstract: We will use the knot Floer complex, in particular the invariant epsilon, to define a new smooth concordance homomorphism. Applications include a formula for tau of iterated cables, better bounds (in many cases) on the 4-ball genus than tau alone, and a new infinite family of smoothly independent topologically slice knots. We will also discuss various algebraic properties of this new homomorphism.

January 28, 2011

Penka Georgieva, "Open Gromov-Witten disk invariants"

Abstract: In the presence of an anti-symplectic involution with a non-empty fixed locus on a symplectic manifold M, open Gromov-Witten disk invariants were defined by Cho and Solomon when the dimension of M is less than or equal to 6. I will describe a generalization to higher dimension under some technical conditions. Time permitting, I will discuss a connection to real algebraic geometry and an approach to relax the conditions.

February 4, 2011

Pierre Schapira, "Sheaf quantization of Hamiltonian isotopies and applications"

Abstract: Recently Tamarkin presented a new approach to symplectic topology based on the microlocal theory of sheaves. For that purpose he had to adapt this theory which relies on the homogeneous symplectic structure to the non homogeneous case. Here, we remain in the homogeneous symplectic setting and prove various results of non displaceability, including the conservation of Morse inequalities as well as some results specific to positive isotopies. The main tool is a theorem which asserts that any Hamiltonian isotopy admits a unique sheaf quantization.

February 11, 2011

Chris Woodward, "Behavior of Gromov-Witten invariants under birational transformations of git type"

Abstract: Various authors (Ruan etc.) have noticed that a functoriality property for Gromov-Witten invariants under certain birational transformations seems to hold. I will describe a formula for the change in Gromov-Witten invariants under a birational transformation of git type, that is, induced by change of git polarization/shift of moment map; the wall-crossing terms are a sum of { — gauged Gromov-Witten invariants}. In the special case of a Calabi-Yau flop, the graph (or descendent) potentials are almost everywhere equal in the quantum parameter. (Many special cases of these results were already known; this is part of a joint project with E. Gonzalez.)

February 25, 2011

James Pascaleff, "Floer cohomology in the mirror of CP^2 relative to a conic and a line"

Abstract: In the Strominger-Yau-Zaslow description of mirror symmetry, singularities of the torus fibration lead to difficulties in the construction of mirror spaces and the computation of algebraic structures associated to these spaces. We will discuss one such algebraic structure, the Floer cohomology of Lagrangian sections of the torus fibration, in a space with a simple type of singularity, the Landau-Ginzburg mirror of CP^2 relative to a conic and a line, along with some natural generalizations. Of particular interest will be the canonical basis for the Floer cohomology groups (and hence of sheaf cohomology groups on CP^2) that our construction gives rise to.

March 4, 2011

Bulent Tosun, "Legendrian and transverse knots in cabled knot types"

Abstract: In this talk we will exhibit many new phenomena in the structure of Legendrian and transverse knots by giving a complete classification of all cables of the positive torus knots. We will also provide two structural theorems to ensure when cable of a Legendrian simple knot type is also Legendrian simple. Part of the results are joint work with John Etnyre and Douglas LaFountain

March 11, 2011

Thomas Kragh, "Fibration properties of symplectic homology and the Nearby Lagrangian conjecture"

Abstract: I will start by describing finite reductions of the action integral and the geometric intuition behind them. I will then use this on an exact Lagrangian L in the cotangent bundle of N, and describe why the symplectic homology associated to the cotangent bundle of L can be viewed as fibrant over N. Considering products this yields the result that the map L to N is a homology equivalence after passing to a finite covering space lift of N.

March 18, 2011

Spring break. No seminar.

March 25, 2011

Alexandra Popa, "On Mirror Formulas in Open and Closed Gromov-Witten Theory"

Abstract: In 2007 J. Walcher defined annulus Gromov-Witten invariants for some Calabi-Yau threefolds endowed with an anti-holomorphic involution as sums over fixed loci graphs of rational expressions in torus weights. He predicted these sums to be rational numbers and conjectured an explicit formula. This formula indeed holds for the quintic and bicubic threefolds (the only projective complete intersection Calabi-Yau threefolds for which these invariants are nonzero). I will explain Walcher’s definition, the key role played by an explicit mirror formula for two point closed Gromov-Witten invariants in the proof of his annulus formula, and ideas behind the proof of the two point formula. This is joint work with Aleksey Zinger.

April 1, 2011

Yanki Lekili, "Fukaya categories of the torus and Dehn surgery"

Abstract: In joint work with Tim Perutz, we extend the Heegaard Floer theory of Ozsvath-Szabo to compact 3-manifolds with two boundary components. In the particular case of 3-manifolds bounding the 2-sphere and the 2-torus, the simplest version of this extension takes the form of an A-infinity module over the Fukaya category of a once punctured torus. After giving an overview of this extension, I will show that the A-infinity structures on the graded algebra A underlying the Fukaya category of the punctured 2-torus are governed by just two parameters, extracted from the Hochschild cohomology of A. Finally, I will discuss that the dg-categories of sheaves on the Weierstrass family of elliptic curves yield a way to realize all such A-infinity structures. This pins down a complete description of the Fukaya A-infinity algebra of the punctured torus, which prove to be non-formal.

April 8, 2011, 9:30 am

Mohammed Abouzaid, "On Homological Mirror Symmetry for Toric varieties"

Abstract: I will explain a criterion involving Quantum cohomology, used to detect whether a collection of Lagrangians split-generate the Fukaya category of a symplectic manifold. We will then see that this criterion applies to toric manifolds, and shows that there is always a finite collection of fibres of the moment map which generate the Fukaya category in these examples. Time permitting, I will explain how to derive a proof of the Homological Mirror Symmetry conjecture in this case. This is joint work with Fukaya, Oh, Ohta, and Ono.

April 8, 2011, 10:45 am

Dan Rutherford, "A combinatorial Legendrian knot DGA from generating families"

Abstract: This is joint work with Brad Henry. A generating family for a Legendrian knot $L$ in standard contact $\mathbb{R}^3$ is a family of functions $f_x$ whose critical values coincide with the front projection of $L$. Pushkar introduced combinatorial analogs of generating families which have become known as Morse complex sequences. In this talk, I will describe how to associate a differential graded algebra (DGA) to a Legendrian knot with chosen Morse complex sequence. In addition, I will discuss the geometric motivation from generating families and the relationship with the Chekanov-Eliashberg invariant.

April 15, 2011

Frol Zapolsky, "On the Hofer geometry on the space of Lagrangians"

Abstract: Consider the set of Lagrangian submanifolds of a symplectic manifold obtained by applying the elements of the Hamiltonian group to a fixed Lagrangian. This space inherits a quotient metric from the Hofer metric on the Hamiltonian group. Very little is known about this metric space in general and I'll present some new results shedding light on it. This is a work in progress, joint with Misha Khanevsky.

April 22, 2011, 9:30 am

Chris Schommer-Pries, "The Structure of Fusion Categories via Topological Quantum Field Theories"

Abstract: Fusion categories arise in several areas of mathematics and physics - conformal field theory, operator algebras, representation theory of quantum groups, and others. They have a rich an fascinating structure. In this talk we will explain recent work, joint with Christopher Douglas and Noah Snyder, which ties this structure to the structure of 3-dimensional topological quantum field theories. In particular we show that fusion categories are fully-dualizable objects in a certain natural 3-category and identify the induced O(3)-action on the `space' of fusion categories, as predicted by the cobordism hypothesis. In light of Hopkins' and Lurie's work on the cobordism hypothesis, this provides a fully local 3D TQFT for arbitrary fusion categories. Moreover by understanding various homotopy fixed point spaces, we will uncover how many familiar structures from the theory of fusion categories are given a natural explanation from the point of view of 3D TQFTs.

April 22, 2011, 10:45 am

Yongbin Ruan, "Gromov-Witten theory of elliptic orbifold P^1 and quasi-modular form"

Abstract: Gromov-Witten invariants counts the number of pseudo-holomorphic curves. One often write them in terms of generating functions. Occasionally, it posses some very beautiful properties such as being a quasi-modular form. In the talk, we will explain this phenomenon for elliptic orbifold P^1. This is a joint work with Milanov, Krawitz and Shen.

April 29, 2011

Tye Lidman, "Heegaard Floer Homology and Triple Cup Products"

Abstract: We use the recent link surgery formula of Manolescu and Ozsv\'ath as well as the theory of surgery equivalence of three-manifolds due to Cochran, Gerges, and Orr to relate Heegaard Floer homology to the cup product structure for a closed, oriented three-manifold. In particular, we give a complete calculation of the infinity flavor of Heegaard Floer homology for torsion Spin$^c$ structures, which is related to the analogous computation for monopole Floer homology with rational coefficients.

May 13, 2011

David Treumann, "Constructible sheaves, plumbings, and homological mirror symmetry"

Abstract: The talk will be based on joint work with Nicolo Sibilla and Eric Zaslow. Kontsevich proposed in 2009 that the Fukaya category of an exact symplectic manifold should be computable locally on a Lagrangian skeleton. I will discuss the compatibility of this idea with Kashiwara and Schapira's microlocal sheaf theory and results of Nadler and Zaslow. Microlocal sheaf theory allows us to associate a category (the "constructible plumbing model" or CPM) in a combinatorial way to a "formal skeleton." Conjecturally CPM is equivalent to the Fukaya category of a suitable symplectic neighborhood. Formal skeleta arise from a T-duality process at the large complex structure limit X_0 of a projective hypersurface X, and we can prove that the category of perfect complexes on X_0 is equivalent to CPM of the associated skeleton.

Other relevant information


  • Moduli Spaces and Moduli Stacks
    A conference on moduli of curves, stable maps, vector bundles, coherent sheaves, and the like, and on recent developments in the theory of algebraic stacks.
    Columbia University
    May 23 – 27, 2011
  • Walterfest!
    Faces of Geometry: 3-Manifolds, Groups, and Singularities
    A Conference in Honor of Walter Neumann
    Columbia University
    June 6–10, 2011

Other area seminars

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Announcements for this seminar, as well as for related seminars and events, are sent to the "Floer Homology" e-mail list maintained via Google Groups. You can subscribe directly via Google Groups or by contacting R. Lipshitz.