The gradient flow of the L^2 curvature energy

Speaker: 

Professor Jeff Streets

Institution: 

UC Irvine

Time: 

Tuesday, February 14, 2012 - 4:00pm

Location: 

RH 306

The L^2 norm of the Riemannian curvature tensor is a natural intrinsic analogue of the Yang-Mills energy in purely Riemannian geometry. To understand the structure of this functional, it is natural to consider the gradient flow. I will give an overview of the analytic theory behind this flow, and discuss some long time existence results in low dimensions. Finally I will mention some natural conjectures for this flow and their consequences.

Balanced metrics on ruled manifolds

Speaker: 

Professor Reza Seyyedali

Institution: 

UC Irvine

Time: 

Tuesday, January 31, 2012 - 3:00pm

Location: 

RH 306

In 2001, Donaldson proved that the existence of cscK metrics on a
polarized manifold (X,L) with discrete automorphism group implies the
existence of balanced metrics on L^k for k large enough. We show that the
similar statement holds if one twists the line bundle L with a simple
stable vector bundle E. More precisely we show that if E is a simple
stable bundle over a polarized manifold (X,L), (X,L) admits cscK metric
and have discrete automorphism group, then (PE^*, \O(d) \otimes L^k)
admits a balanced metric for k large enough.

Uniqueness of Self-shrinkers of Mean Curvature Flow

Speaker: 

Dr. Lu Wang

Institution: 

MSRI and Johns-Hopkins

Time: 

Tuesday, December 6, 2011 - 4:00pm

Location: 

RH 306

Recently, using the desingularization technique, a new family of complete properly embedded self-shrinkers asymptotic to cones in three dimensional Euclidean space has been constructed by Kapouleas-Kleene-Moeller and independently by Nguyen.

In this talk, we present the uniqueness of self-shrinking ends asymptotic to any given cone in general Euclidean space. The feature of our uniqueness result is that we do not require the control on the boundaries of self-shrinking ends or the rate of convergence to cones at infinity. As applications, we show that, there do not exist complete properly embedded self-shrinkers other than hyperplanes having ends asymptotic to rotationally symmetric cones.

Minimal Lagrangian immersions in CH^2

Speaker: 

Professor Zheng Huang

Institution: 

CUNY, Staten Island

Time: 

Wednesday, January 18, 2012 - 3:00pm

Location: 

RH 306

We consider the problem of minimal Lagrangian immersions of disks into CH^2 which are equivariant to some surface group representation. We prove several results on existence and (non)uniqueness. The local parameterization of the immersion is given by the conformal structure on a closed surface and a holomorphic cubic differential on that conformal structure, hence of complex dimension 8g-8, where g>1 is the genus. This is a joint work with John Loftin and Marcello Lucia.

Volume estimates for metric measure spaces

Speaker: 

Professor Detang Zhou

Institution: 

Universidade Federal Fluminense

Time: 

Tuesday, January 10, 2012 - 4:00pm

Location: 

RH 306

A smooth metric space is a Riemanian manifold together with a weighted volume. It is naturally associated with a weighted Laplacian. In this talk, I will discuss some recent results about function theoretic and spectral propeties of the weighted Laplacian and volume estimates for the volume and weighted volume. The results can be applied to study the shrinking gradient Ricci solitons and self-shrinker for mean curvature flows.

On four-dimensional anti-self-dual gradient Ricci solitons

Speaker: 

Professor Yuanqi Wang

Institution: 

UCSB

Time: 

Tuesday, November 15, 2011 - 4:00pm

Location: 

RH 306

Classification of 4-dim gradient Ricci solitons is important to the
study of 4-dim Ricci flow with surgeries. My talk will be based on our classification of anti-self-dual gradient shrinking Ricci solitons and our results on anti-self-dual steady Ricci solitons. This is highly related to the analyticity of Ricci solitons. I will also discuss something on anti-self-dual Ricci flows.

Asymptotic spectral flow for Dirac operators of disjoint Dehn twists

Speaker: 

Dr. Chung-Jun Tsai

Institution: 

NCTS, National Taiwan University

Time: 

Tuesday, January 24, 2012 - 4:00pm

Location: 

RH 306

In Taubes' proof of the Weinstein conjecture, a main ingredient is the estimate on the spectral flow of a family of Dirac operators, which he used to obtain the energy bound. When the perturbation is a contact form, much evidence suggests that the asymptotic behavior of the spectral flow function is nicer. In this talk, we will explain how to improve the spectral flow estimate for some classes of contact forms.

Curvature and rational connectivity on projective manifolds

Speaker: 

Professor Bun Wong

Institution: 

UC Riverside

Time: 

Tuesday, November 22, 2011 - 4:00pm

Location: 

RH 306

In this lecture, we will talk about a recent joint
work of Gordon Heier and myself about curvature characterizations
of uniruledness and rational connectivity of projective manifolds. A
result on projective manifolds with zero total scalar curvature will
also be discussed.

Integrable systems and invariant curve flows in certain geometries

Speaker: 

Professor Changzheng Qu

Institution: 

Northwestern University in Xian, China

Time: 

Tuesday, November 29, 2011 - 4:00pm

Location: 

RH 306

In this talk, the relationship between integrable systems and invariant curve flows is studied. It is shown that many integrable systems including the well-known integrable equations and Camassa-Holm type equations arise from the non-stretching invariant curve flows in Klein geometries. The geometrical formulations to some properties of integrable systems are also given.

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