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.

Homological rigidity of Schubert varieties in compact Hermitian symmetric spaces

Speaker: 

Professor Colleen Robles

Institution: 

Texas A&M

Time: 

Tuesday, March 1, 2011 - 3:00pm

Location: 

RH 306

The integral homology of a compact Hermitian symmetric spaces (CHSS) is generated by the homology classes of its Schubert varieties. Most Schubert varieties are singular. In 1961 Borel and Haefliger asked: when can the homology class [X] of a singular Schubert variety be represented by a smooth subvariety Y of the CHSS?

Remarkably, the subvarieties Y with [Y] = [X] are integrals of a (linear Pfaffian) differential system. I will discuss recent work with Dennis The in which we give a complete list of those Schubert varieties X for which there exists a first-order obstruction to the existence of a smooth Y. This extends (independent) work of M. Walters, R. Bryant and J. Hong.

The sine qua non of our analysis is a new characterization of the Schubert varieties by a non-negative integer and a marked Dynkin diagram. The description generalizes the well-known characterization of the smooth Schubert varieties by subdiagrams of the Dynkin diagram associated to the CHSS.

I will illustrate the talk with examples.

How to recognize a Kahler metric?

Speaker: 

Professor Maciej Dunajski

Institution: 

University of Cambridge, United Kingdom

Time: 

Tuesday, April 12, 2011 - 4:00pm

Location: 

RH 306

Let (M, g) be Riemannian four-manifold. Does there exist a
non-zero function f:M->R such that
(*) f^2 g is flat?
(**) f^2 g satisfies Einstein equations?
Most people know the answer to (*). Nobody (really) knows the full
answer to (**). In this talk I will provide the answer to
(***) f^2 g is Kahler for some Kahler form?

Pages

Subscribe to RSS - Differential Geometry