It has been a challenging problem to studying the existence of Kahler-Einstein metrics on Fano manifolds. A Fano manifold is a compact Kahler manifold with positive first Chern class. There are obstructions to the existence of Kahler-Einstein metrics on Fano manifolds. In these lectures, I will report on recent progresses on the study of Kahler-Einstein metrics on Fano manifolds. The first lecture will be a general one. I will discuss approaches to studying the existence problem. I will discuss the difficulties and tools in these approaches and results we have for studying them. In the second lecture, I will discuss the partial C^0-estimate which plays a crucial role in recent progresses on the existence of Kahler-Einstein metrics. I will show main technical aspects of proving such an estimate.

In large dimensions, the only known compact, simply connected Riemannian manifolds with positive sectional curvature are spheres and projective spaces. The natural metrics on these spaces have large isometry groups, so it is natural to consider highly symmetric metrics when searching for new examples. On the other hand, there are many topological obstructions to a manifold admitting a positively curved metric with large symmetry. I will discuss a new obstruction in this setting. This is joint work with Manuel Amann (KIT).

Conference website
http://www.math.uci.edu/~scgas/scgas-2014/2014.php

The L2 norm of the Riemannian curvature tensor is a natural energy to associate to a Riemannian manifold, especially in dimension 4.  A natural path for understanding the structure of this functional and its minimizers is via its gradient flow, the "L2 flow."  This is a quasi-linear fourth order parabolic equation for a Riemannian metric, which one might hope shares behavior in common with the Yang-Mills flow.  We verify this idea by exhibiting structural results for finite time singularities of this flow resembling results on Yang-Mills flow.  We also exhibit a new short-time existence statement for the flow exhibiting a lower bound for the existence time purely in terms of a measure of the volume growth of the initial data.  As corollaries we establish new compactness and diffeomorphism finiteness theorems for four-manifolds generalizing known results to ones with have effectively minimal hypotheses/dependencies.  These results all rely on a new technique for controlling the growth of distances along a geometric flow, which is especially well-suited to the L2 flow.

Abstract: This talk will provide an overview of the renormalized volume
coefficients and associated renormalized volume functionals in conformal
geometry. These are Riemannian invariants constructed from the volume
expansion of a Poincar\'e-Einstein metric with a prescribed conformal
infinity. They arose in the context of the AdS/CFT correspondence in
physics. They have some surprising properties, which, among other things,
suggests a natural variant of the so-called $\sigma_k$-Yamabe problem, a
fully nonlinear generalization of the Yamabe problem which has been the
focus of much attention during the last decade.