Upcoming Seminars & Events

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September 16, 2014
2:00pm - 3:30pm
Hodge theory and derived categories of cubic fourfolds
Speaker: Richard Thomas , Imperial College - London
Location:
IAS Room S-101
September 16, 2014
3:30pm - 5:00pm
Generic K3 categories and Hodge theory
Speaker: Daniel Huybrechts, Bonn University
Location:
IAS Room S-101
September 16, 2014
4:30pm - 5:30pm
Regular operator mappings and multivariate geometric means

We introduce the notion of regular operator mappings of several variables generalising the notion of spectral function. This setting is convenient for studying maps more general than what can be obtained from the functional calculus, and it allows for Jensen type inequalities and multivariate non-commutative perspectives.

Speaker: Frank Hansen, Tohoku University
Location:
Jadwin Hall 343
September 18, 2014
3:00pm - 4:00pm
Expansion of Random Graphs - New Proofs, New Results

We present a new approach to showing that random graphs are nearly optimal expanders. This approach is based on deep results from combinatorial group  theory. It applies to both regular and irregular random graphs.  Let G be a random d-regular graph on n vertices.

Speaker: Doron Puder, IAS
Location:
Fine Hall 224
September 18, 2014
3:00pm - 4:00pm
Loop space homology, string homology, and closed geodesics

The homology of free loop space of a manifold enjoys additional structure first identified by Chas and Sullivan. The string multiplication has been studied by Ralph Cohen and John Jones and together with J.~Yan, they have introduced a spectral sequence converging to string homology that is related to the Serre spectral sequence for the free loop space.

Speaker: John McCleary, Vassar College
Location:
Fine Hall 214
September 18, 2014
4:30pm - 5:30pm
Combinatorial tangle Floer homology

In joint work with Vera Vertesi, we extend the functoriality in Heegaard Floer homology by defining a Heegaard Floer invariant for tangles which satisfies a nice gluing formula. We will discuss the construction of this combinatorial invariant for tangles in S^3, D^3, and I x S^2. The special case of S^3gives back a stabilized version of knot Floer homology.

Speaker: Ina Petkova, Rice University
Location:
Fine Hall 314
September 18, 2014
4:30pm - 5:30pm
Iwasawa Main Conjecture for Supersingular Elliptic Curves

We will describe a new strategy to prove the plus-minus main conjecture for elliptic curves having good supersingular reduction at p. It makes use of an ongoing work of Kings-Loeffler-Zerbes on explicit reciprocity laws for Beilinson-Flach elements to reduce to another main conjecture of Greenberg type, which can in turn be proved using Eisenstein congruences on the unitary group U(3,1).

Speaker: Xin Wan , Columbia University
Location:
Fine Hall 214
September 19, 2014
3:00pm - 4:00pm
On the topology and index of minimal surfaces

We show that for an immersed two-sided minimal surface in R^3, there is a lower bound on the index depending on the genus and number of  ends. Using this, we show the nonexistence of an embedded minimal surface

Speaker: Davi Maximo, Stanford University
Location:
Fine Hall 314
September 22, 2014
3:15pm - 4:30pm
A modulated two-soliton with transient turbulent regime for a focusing cubic nonlinear half-wave equation on the real line

In this talk we discuss work in progress regarding a nonlocal focusing cubic half-wave equation on the real line. Evolution problems with nonlocal dispersion naturally arise in physical settings which include models for weak turbulence, continuum limits of lattice systems, and gravitational collapse.

Speaker: Oana Pocovnicu , Princeton University
Location:
Fine Hall 314
September 22, 2014
4:30pm - 5:30pm
Asymptotics beyond all orders: the devil's invention?

"Divergent series are the invention of the devil, and it is shameful to base on them any demonstration whatsoever." --- N. H. Abel. The lecture will introduce the concept of an asymptotic series, showing how useful divergent series can be, despite Abel's reservations. We will then discuss Stokes' phenomenon, whereby the coefficients in the series appear to change discontinuously.

Speaker: Jonathan Chapman , Oxford University
Location:
Fine Hall 214
September 23, 2014
4:30pm - 5:30pm
Statistical Mechanics on Sparse Random Graphs: Mathematical Perspective

Theoretical physics studies of disordered materials lead to challenging mathematical problems with applications to random combinatorial problems and coding theory. The underlying structure is that of many discrete variables that are strongly interacting according to a mean field model determined by a random sparse graph.

Speaker: Amir Dembo, Stanford University
Location:
Jadwin Hall 343
September 25, 2014
11:30am - 12:30pm
Symplectic fillings and star surgery

This is a joint Symplectic Geometry-Topology seminar.  Please note special time and location.    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.

Speaker: Laura Starkson , University of Texas at Austin
Location:
TBD
September 25, 2014
11:30am - 12:30pm
Symplectic fillings and star surgery

This is a joint Topology-Symplectic Geometry seminar.  Please note special time and location.    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.

Speaker: Laura Starkson , University of Texas at Austin
Location:
TBD
September 25, 2014
3:00pm - 4:00pm
Excluding topological minors and well-quasi-ordering

Robertson and Seymour proved that graphs are well-quasi-ordered by the minor relation and the weak immersion relation. In other words, given infinitely many graphs, one graph contains another as a minor (or a weak immersion, respectively). Unlike the relation of minor and weak immersion, the topological minor relation does not well-quasi-order graphs in general.

Speaker: Chun-Hung Liu , Princeton University
Location:
Fine Hall 224
September 26, 2014
3:00pm - 4:00pm
Umbilicity and characterization of Pansu spheres in the Heisenberg group

For n≥2 we define a notion of umbilicity for hypersurfaces in the Heisenberg group H_{n}. We classify umbilic hypersurfaces in some cases, and prove that Pansu spheres are the only umbilic spheres with positive constant p(or horizontal)-mean curvature in H_{n} up to Heisenberg translations. This is joint work with Hung-Lin Chiu, Jenn-Fang Hwang, and Paul Yang. 

Speaker: Jih-Hsin Cheng , Academia Sinica, Taiwan
Location:
Fine Hall 314
September 29, 2014
3:15pm - 4:30pm
Focal points and sup-norms of eigenfunctions

If (M,g) is a compact real analytic Riemannian manifold, we give a necessary and sufficient condition for there to be a sequence of quasimodes saturating sup-norm estimates.  The condition is that there exists a self-focal point x_0\in M for the geodesic flow at which the associated Perron-Frobenius operator U: L^2(S_{x_0}^*M) \to L^2(S_{x_0}^*M) has a nontrivial invariant function.

Speaker: Christopher Sogge, Johns Hopkins University
Location:
Fine Hall 110
September 29, 2014
4:30pm - 5:30pm
TBA - Wang
Speaker: Qian Wang , University of Oxford, England
Location:
Fine Hall 110
September 29, 2014
4:30pm - 5:30pm
Applications of diffusion maps in dynamical systems

There is great current interest in the use of diffusion maps for dimension reduction. We discuss some examples of diffusion methods applied to understanding dynamical data, in particular combining spectral approaches with delay coordinates. In addition, we extend the usual diffusion map construction by introducing local kernels, a generalization of the standard isotropic kernel.

Speaker: Tim Sauer , George Mason University
Location:
Fine Hall 214
October 1, 2014
2:00pm - 3:00pm
Increasing subsequences on the plane and the Slow Bond Conjecture

For a Poisson process in R^2 with intensity 1, the distribution of the maximum number of points on an oriented path from (0,0) to (N,N) has been studied in detail, culminating in Baik-Deift-Johansson's celebrated Tracy-Widom fluctuation result.

Speaker: Allan Sly , UC Berkeley
Location:
Fine Hall 322
October 2, 2014
3:00pm - 4:00pm
TBA - Scott
Speaker: Alex Scott, Oxford University
Location:
Fine Hall 224

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