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.

Symplectic curvature flow

Speaker: 

Professor Jeff Streets

Institution: 

Princeton

Time: 

Thursday, May 26, 2011 - 4:00pm

Location: 

RH 306

I will introduce a parabolic flow of almost K\"ahler structures,
providing an approach to constructing canonical geometric structures on symplectic manifolds. I will exhibit this flow as one of a family of parabolic flows of almost Hermitian structures, generalizing my previous work on parabolic flows of Hermitian metrics. I will exhibit a long time existence obstruction for solutions to this flow by showing certain smoothing estimates for the curvature and torsion. Finally I will discuss the limiting objects as well as some open problems related to the symplectic
curvature flow.

Surfaces of constant mean curvature: theory and experiments

Speaker: 

Professor Franz Pedit

Institution: 

UMass Amherst and University of Tuebingen

Time: 

Tuesday, March 8, 2011 - 4:00pm

Location: 

RH 306

Surfaces of constant mean curvature (CMC) are a prime example of an integrable system. We will focus on the classification of compact CMC surfaces and outline the complete classification in genus one. Flows on the moduli space of CMC cylinders will provide a fine structure relating CMC tori to closed curves in 3-space, another well known integrable system. Computer images and experiments will be used to demonstrate the theoretical concepts.

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