We discuss recent progress on understanding singular special Lagrangian n-folds. Our focus will be on joint work with N. Kapouleas using gluing methods to construct a wide variety of special Lagrangian cones in every dimension three and greater.
Colding and Minicozzi have shown that if an embedded minimal disk in $B_R\subset\Real^3$ has large curvature then in a smaller ball, on a scale still proportional to $R$, the disk looks roughly like a piece of a helicoid. In this talk, we will see that near points whose curvature is relatively large the description can be made more precise. That is, in a neighborhood of such a point (on a scale $s$ proportional to the inverse of the curvature of the point) the surface is bi-Lipschitz to a piece of a helicoid. Moreover, the Lipschitz constant goes to 1 as $Rs$ goes to $\infty$ . This follows from Meeks and Rosenberg's result on the uniqueness of the helicoid of which, time permitting, we will discuss a new proof. Joint work with C. Breiner.
I'll discuss joint work with Peter Petersen that shows that the Gromoll-Meyer exotic 7-sphere admits positive sectional curvature. I'll discuss the history of the problem and give a coarse outline of our solution.
In this talk I will discuss some general conditions such that the Poisson equation can be solved on a complete manifold. Existence of harmonic maps between complete manifolds and existence of Hermitian-Einstein metrics on holomorphic vector bundles over complete manifolds will be mentioned as applications. This is joint work with Natasa Sesum.
In this talk, we present a characterization of the Christoeffel pairs of timelike isothermic surfaces in the four-dimensional split-quaternions. When restricting the receiving space to the three-dimensional imaginary split-quaternions, we establish an equivalent condition for a timelike surface in $R^3_2$ to be real or complex isothermic in terms of the existence of integrating factors. This is joint work with M. Magid (Wellesley College).
As the complex version of Ricci flow, K\"ahler-Ricci flow enjoys the special feature, i.e., cohomology information for the evolving K\"ahler metric. The flow can thus be reduced to scalar level as first used by H. D. Cao in the alternative proof of Calabi's Conjecture. People have mostly been focusing on the situation when the K\"ahler class is fixed. As first considered by H. Tsuji, by allowing the class to evolve, the flow can be applied in the study of degenerate class, for example, class on the boundary of K\"ahler cone. We discuss some results in this drection. This is the geometric analysis aspect of Tian's program, which aims at applying K\"ahler-Ricci flow in the study of algebraic geometry objects with great interests.
By trace map we mean the following polynomial map of R^3:
T(x,y,z)= (2xy-z, x, y).
Despite of its simple form, it is related to complicated mathematical objects such as character varieties of some surfaces, Painlev\'e sixth equation, and discrete Schr\"odinger operator with Fibonacci potential. We will present some very recent results on dynamics of the trace map and discuss their applications. These is a joint project with D.Damanik.
We call a metric quasi-Einstein if the m-Bakry-Emery Ricci tensor is a constant multiple of the metric tensor. This is a generalization of Einstein metrics, which contains gradient Ricci solitons and is also closely related to the construction of the warped product Einstein metrics. We study properties of quasi-Einstein metrics and prove several
rigidity results. We also give a splitting theorem for some Kahler quasi-Einstein metrics.
We classify compact ancient solutions of the curve
shortening flow and the Ricci flow on Surfaces. We show that these are either a family of contracting circles (contracting spheres in the case of the Ricci flow on surfaces), which is a type I ancient solution,or a family of Angenent ovals (Rosenau solutions in the case of the Ricci flow on surfaces), which corresponds to a type II
solution.