Seminars Sorted by Series

A remarkable phenomenon in Gromov-Witten theory is the appearance of (quasi)-modular forms. For example, Gromov-Witten generating functions for elliptic curve, local $\mathbb{P}^2$, elliptic orbifold $\mathbb{P}^1$ are all (quasi)-modular forms. In...

We study open-closed orbifold Gromov-Witten invariants of toric Calabi-Yau 3-orbifolds with respect to Lagrangian branes of Aganagic-Vafa type. We prove an open mirror theorem which expresses generating functions of orbifold disk invariants in terms...

A symplectic pencil is a linear family of symplectic forms, i.e., a linear space of two-forms, each of which, except of course the zero form, is symplectic. Symplectic pencils arise, for instance, from representations of Clifford algebras and can be...

Origami manifolds and b-symplectic manifolds are examples of manifolds which are symplectic except on a hypersurface Z: in the origami case, the symplectic form vanishes at Z; in the b-case, it explodes to infinity at Z. In this talk we will...

We will present joint work with Will Merry. Using spectral invariants in Rabinowitz Floer homology we present an abstract contact non-squeezing theorem for periodic contact manifolds. We then exemplify this in concrete examples. Finally we explain...

The string topology of Chas-Sullivan produces operations on the homology of the free loop space of orientable manifolds, and analogous structures are known to exist on the symplectic cohomology of their cotangent bundles. Work of Kragh has shown...

In 1985 Misha Gromov proved his Nonsqueezing Theorem, and hence constructed the first symplectic 1-capacity. In 1989 Helmut Hofer asked whether symplectic d-capacities exist if 1 d n. I will discuss the answer to this question and its relevance in...

I will present a recent result (joint with Yakov Eliashberg) demonstrating the existence of exact Lagrangian cobordisms with a loose Legendrian in the negative end, in all dimensions greater than 4. In particular, we show that there exists a...

Fix a metric (Riemannian or Finsler) on a compact manifold M. The critical points of the length function on the free loop space LM of M are the closed geodesics on M. Filtration by the length function gives a link between the geometry of closed...

If X is a Riemannian manifold, the Laplacian is a second order elliptic operator on X. The hypoelliptic Laplacian L_b is an operator acting on the total space TX of the tangent bundle of X, that is supposed to interpolate between the elliptic...

This is joint work with A. B. Goncharov. To any convex integer polygon we associate a Poisson variety, which is essentially the moduli space of connections on line bundles on (certain) bipartite graphs on a torus. There is an underlying integrable...

A 7-dimensional Riemannian manifold (M,g) is called a G_2 manifold if the holonomy group of its Levi-Civita connection of g lies inside G_2. In this talk, I will first give brief introductions to G_2 manifolds, and then discuss relations between G_2...

To apply the technique of virtual fundamental cycle (chain) in the study of pseudo-holomorphic curve, we need to construct certain structure, which we call Kuranishi strucuture, on its moduli space. In this talk I want to review certain points of...

The talk is intended to give examples of Arnold diffusion for nearly integrable systems which are very likely to be generic. We will describe an explicit perturbation of the flat metric on the three dimensional torus which admits orbits whose...

In this lecture I will explain the moment-weight inequality, and its role in the proof of the Hilbert-Mumford numerical criterion for \(\mu\)-stability. The setting is Hamiltonian group actions on closed Kaehler manifolds. The major ingredients are...

Orderability of contact manifolds is related in some non-obvious ways to the topology of a contact manifold \(\Sigma\). We know, for instance, that if \(\Sigma\) admits a 2-subcritical Stein filling, it must be non-orderable. By way of contrast, in...

I will present some recent joint work with Richard Siefring on the behavior of finite energy foliations under the action of a 0-surgery (i.e. a connect sum) and a 2-surgery. We will then discuss applications to the restricted three body problem.

We consider the problem of defining cylindrical contact homology, in the absence of contractible Reeb orbits, using "classical" methods. The main technical difficulty is failure of transversality of multiply covered cylinders. One can fix this...

The classical problem of enumerating rational curves in projective spaces is solved using a recursion formula for Gromov-Witten invariants. In this talk, I will describe a similar relation for real Gromov-Witten invariants with conjugate pairs of...

I will discuss recent joint work with Vinicius Gripp and Michael Hutchings relating the volume of any contact three-manifold to the length of certain finite sets of Reeb orbits. I will also explain why this result implies that any closed contact...

The Milnor fibre of any isolated hypersurface singularity contains exact Lagrangian spheres: the vanishing cycles associated to a Morsification of the singularity. Moreover, for simple singularities, it is known that the only possible exact...

I will report on joint work with Nick Sheridan concerning structural aspects of mirror symmetry for Calabi-Yau manifolds. We show (i) that Kontsevich's homological mirror symmetry (HMS) conjecture is a consequence of a fragment of the same...

The Gopakumar-Vafa conjecture predicts that the Gromov-Witten invariants of a Calabi-Yau 3-fold can be canonically expressed in terms of integer invariants called BPS numbers. In this talk, based on joint work with Tom Parker, I describe the proof...

Feynman categories are a new universal categorical framework for generalizing operads, modular operads and twisted modular operads. The latter two appear prominently in Gromov-Witten theory and in string field theory respectively. Feynman categories...

First, I will discuss a proof that a Lagrangian torus in \(\mathbb{CP}^2\) arising from a semitoric system described by Weiwei Wu coincides with the image in \(\mathbb{CP}^2\) of Chekanov's exotic Lagrangian torus in \(\mathbb R^4\). I will then...

The time evolution of an ideal incompressible fluid is described by the Euler equations. In this mostly speculative talk I will discuss a connection between stationary solutions of these equations and symplectic topology, as well as possible...

In this talk I will explain how the heuristic arguments sketched in literature since 1999 fail to define a homology theory. These issues will be made clear with concrete examples and we will explore what stronger conditions are necessary to develop...

Ideas of Kontsevich-Soibelman and Fukaya indicate that there is a natural rigid analytic space (the mirror) associated to a symplectic manifold equipped with a Lagrangian torus fibration. I will explain a construction which associates to a...

The Fukaya category of a fibration with singularities \(W: M \to C\), or Fukaya-Seidel category, enlarges the Fukaya category of \(M\) by including certain non-compact Lagrangians and asymmetric perturbations at infinity involving \(W\); objects...

An implicit atlas on a (moduli) space consists of certain auxiliary (moduli) spaces satisfying a precise set of axioms. We will summarize the construction of implicit atlases on moduli spaces of \(J\)-holomorphic curves, under the assumption of a...

Kronheimer and Mrowka recently used monopole Floer homology to define an invariant of sutured manifolds, following work of Juhász in Heegaard Floer homology. In this talk, I will construct an invariant of a contact structure on a 3-manifold with...

I will discuss some results, some older and some newer, on the general idea that in many birationally-Fano cases, generators of the Fukaya category seem to arise from transitions in the minimal model program. A specific result from a couple of years...

Embedded contact homology is an invariant of a contact three-manifold, which is recently shown to be isomorphic to Heegaard Floer homology and Seiberg-Witten Floer homology. However, ECH chain complex depends on the contact form on the manifold and...

We describe the recently observed relation between knot contact homology and open topological strings. This in particular gives two ways of looking at the augmentation variety from knot contact homology, which describe the relevant string theory at...

Witten conjectured a relationship between intersection theory on the moduli space of marked stable curves and the KdV integrable hierarchy. Alternatively, the KdV hierarchy can be rephrased in terms of a representation of half the Virasoro algebra...

More than twenty years ago, Witten proposed a remarkable conjecture connecting the geometry of moduli space of curve or Gromov-Witten theory of point to KdV integrable hierarchies (solved by Kontsevich). Since then, Witten's conjecture opened up a...

In this talk, I will explain the recent joint work with Bohui Chen and Anmin Li on virtual neighborhood techniques for a Fredholm system \((B, E, S)\), where \(E\) is a Banach vector bundle over a Banach manifold \(B\) with a Fredholm section. Using...

I will outline a way to extend the construction of Viterbo's transfer map in symplectic homology to nonexact embeddings of one Liouville domain into another. The approach is motivated by SFT, but at least parts of it can be implemented independently...

Let A be an affine variety inside a complex N dimensional vector space which either has an isolated singularity at the origin or is smooth at the origin. The intersection of A with a very small sphere turns out to be a contact manifold called the...

Although the existence of a symplectic filling is well-understood for many contact 3-manifolds, complete classifications of all symplectic fillings of a particular contact manifold are more rare. Relying on a recognition theorem of McDuff for closed...

We shall discuss two new results concerning gauge-theoretic invariants of "standard" four-manifolds, namely closed, connected, four-dimensional, orientable, smooth manifolds with \(b^1 = 0\) and \(b^+ \geq 3\) and odd. We first describe how the SO(3...

When a variety \(X\) is equipped with the action of an algebraic group \(G\), it is natural to study the \(G\)-equivariant vector bundles or coherent sheaves on \(X\). When \(X\) furthermore has a mirror partner \(Y\), one can ask for the...

After Gromov's foundational work in 1985, problems of symplectic embeddings lie in the heart of symplectic geometry. The Gromov width of a symplectic manifold \((M, \omega)\) is a symplectic invariant that measures, roughly speaking, the size of the...

Symplectic and anti-symplectic embeddings can be characterized as those embeddings that preserve the symplectic capacity (of ellipsoids). This gives rise to a proof of \(C^0\)-rigidity of symplectic embeddings, and in particular, diffeomorphisms....

I will report on recent joint work with L. Katzarkov and M. Kontsevich (arXiv:1409.8611) in which we construct Bridgeland stability conditions on partially wrapped Fukaya categories of surfaces. Stable objects in these stability conditions...

We show that for any symplectic manifold of dimension \(2n > 4\), there exists a symplectic hypersurface Poincare dual to some positive multiple of the symplectic form whose \((n - 2)\)th Betti number is as large as we like. The idea here is to find...

In this talk, we study two natural circle actions in Floer theory, one on symplectic cohomology and one on the Hochschild homology of the Fukaya category. We show that the geometric open-closed string map between these two complexes is \(S^1\)...

This is a joint work with Gang Tian. I will talk about the analytical properties of the classical equation of motion in gauged linear $\sigma$-model, which we call the gauged Witten equation. This is a generalization of the Witten equation in Landau...

I will describe purely symplectic notions of normal crossings divisor and configuration. They are compatible with the existence of the desired auxiliary almost Kahler structures, provided ``existence" is suitably interpreted. These notions lead to a...