The supremum of L^2 normalized random holomorphic fields

Speaker: 

Renjie Feng

Institution: 

University of Maryland

Time: 

Tuesday, October 21, 2014 - 4:00pm

Host: 

Location: 

RH 306

We prove that the expected value and median of the supremum of L^2 normalized random holomorphic fields of degree n on m-dimensional Kahler manifolds are asymptotically of order \sqrt{m\log n}.

There is an exponential concentration of measure of the sup norm around this median value. The estimates are based on the entropy methods of Dudley and Sudakov combined with a precise analysis of the relevant distance functions and covering numbers using off-diagonal asymptotics of Bergman kernels. This is the joint work with S. Zelditch.

The complex geometry of Teichmüller spaces and symmetric domains

Speaker: 

Stergios Antonakoudis

Institution: 

University of Cambridge

Time: 

Tuesday, October 28, 2014 - 4:00pm

Location: 

RH 306

From a complex analytic perspective Teichmüller space - the universal
cover of the moduli space of Riemann surfaces - is a contractible
bounded domain in a complex vector space. Likewise, Bounded Symmetric
domains arise as the universal covers of locally symmetric varieties
(of non-compact type). In this talk we will study isometric maps
between these two important classes of bounded domains equipped with
their intrinsic Kobayashi metric.

On the Kahler Ricci Flow

Speaker: 

Bing Wang

Institution: 

University of Wisconsin, Madison

Time: 

Tuesday, November 18, 2014 - 4:00pm

Location: 

RH 306

Based on the compactness of the moduli of non-collapsed Calabi-Yau
spaces with mild singularities, we set up a structure theory for
polarized K\"ahler Ricci flows with proper geometric bounds.
Our theory is a generalization of the structure theory
of non-collapsed K\"ahler Einstein manifolds.
As applications, we prove the Hamilton-Tian conjecture and the partial-
C0-conjecture of Tian. This is a joint work with Xiuxiong Chen.

Groups of Asymptotic Diffeomorphisms

Speaker: 

Robert McOwen

Institution: 

Northeastern University

Time: 

Tuesday, October 7, 2014 - 4:00pm

Host: 

Location: 

RH 306

We consider classes of diffeomorphisms of Euclidean space with partial asymptotic expansions at infinity; the remainder term lies in a weighted Sobolev space whose properties at infinity fit with the desired application. We show that two such classes of asymptotic diffeomorphisms form topological groups under composition. As such, they can be used in the study of fluid dynamics according to the method of V. Arnold. Specific applications have been obtained for the Camassa-Holm equation and the Euler equations.

Flat bundles, harmonic metrics and singular affine structures

Speaker: 

Adam Jacob

Institution: 

Harvard University

Time: 

Tuesday, May 27, 2014 - 4:00pm

Location: 

RH 306

There is a natural correspondence between holomorphic
bundles over complex manifolds and flat bundles over affine
manifolds. More specifically, an elliptic K3 surface can be viewed as
a torus fibration over P^1, and away from the singular fibers a torus
invariant holomorphic bundle reduces to a flat bundle over punctured
P^1. In this talk I will describe and solve the reduction of the
Hermitian-Yang-Mills equations to a flat bundle on this Riemann
surface, and discuss its relation to twisted harmonic metrics and
mirror symmetry. This is joint work with T.C. Collins and S.-T. Yau.

Generating Fukaya categories in homological mirror symmetry

Speaker: 

Tim Perutz

Institution: 

UT Austin

Time: 

Tuesday, May 20, 2014 - 4:00pm

Location: 

RH 306

I'll report on joint work with Nick Sheridan (Princeton/IAS) about mirror symmetry for Calabi-Yau (CY) manifolds. Kontsevich's homological mirror symmetry (HMS) conjecture proposes that the Fukaya category of a CY manifold (viewed as a symplectic manifold) is equivalent to the derived category of coherent sheaves on its mirror. We show that if one can prove an apparently weaker fragment of this conjecture, for some mirror pair, then one can deduce HMS for that pair. We expect this fragment  to be amenable to proof for the mirror pairs constructed in the Gross-Siebert program, for example.  We also show that the "closed-open string map" is an isomorphism, thereby opening a channel for proving the "closed string" predictions of mirror symmetry.

Introduction to complex projective structure

Speaker: 

Shinpei Baba

Institution: 

Caltech

Time: 

Tuesday, May 13, 2014 - 4:00pm

Location: 

RH 306

A (complex) projective structure is a geometric structure
on a real surface, and it is a refinement of a complex structure.
In addition each projective structure enjoys  a homomorphism of the
fundamental group of the surface into PSL(2,C), which is called
holonomy representation.

We discuss about some well-known results and basic examples of
complex projective structures.  In addition, we talk about different
projective structures sharing such a homomorphism.

Isoperimetric inequality and Q-curvature

Speaker: 

Yi Wang

Institution: 

Stanford University

Time: 

Tuesday, April 29, 2014 - 4:00pm

Location: 

RH 306

A well-known question in differential geometry is to prove the
isoperimetric inequality under intrinsic curvature conditions. In
dimension 2, the isoperimetric inequality is controlled by the integral of
the positive part of the Gaussian curvature. In my recent work, I prove
that on simply connected conformally flat manifolds of higher dimensions,
the role of the Gaussian curvature can be replaced by the Branson's
Q-curvature. The isoperimetric inequality is valid if the integral of the
Q-curvature is below a sharp threshold. Moreover, the isoperimetric
constant depends only on the integrals of the Q-curvature. The proof
relies on the theory of A_p weights in harmonic analysis.

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