Focusing on the Lie group SU(n) and associated symmetric spaces,
I investigate two related topics. The main result is that the bi-invariant
Einstein metric on SU(2n+1) is isolated in the moduli space of Einstein
metrics, even though it admits infinitesimal deformations. This gives a
non-Kaehler, non-product example of this phenomenon adding to the famous
example of Koiso from the eighties.  I also explore the relationship between
the question of rigidity and instability (under the Ricci flow) of Einstein
metrics, and present results in this direction for complex Grassmannians.

On symplectic manifolds, there are intrinsincally symplectic cohomologies of differential forms that are analogous to the Dolbeault cohomology on complex manifolds. These cohomologies are isomorphic to the de Rham cohomologies on odd-dimensional sphere bundles over the symplectic manifold. In this talk, I will describe how we can use this sphere bundle perspective to define a novel Morse-type theory on symplectic manifolds associated with the symplectic cohomologies. This is joint work with Xiang Tang and Li-Sheng Tseng.

The generalized Ricci flow is first studied by Streets and Tian.
It can be viewed as the Ricci flow of connections with torsion which has
many applications in non-Kähler geometry. In this talk, we will study the
fixed points of the generalized Ricci flow which are called the steady
generalized Ricci solitons. Similar to Ricci flow, generalized Ricci flow is
also a gradient flow so we can further compute the variation formulas and
see some linear stable examples. Our main result is to show that the concept
of dynamical stability and linear stability are equivalent on the steady
gradient generalized Ricci solitons.

The Monge-Ampere equation det(D^2 u) = 1 arises in prescribed
curvature problems and in optimal transport. An interesting feature of the
equation is that it admits singular solutions. We will discuss new examples
of convex functions on R^n that solve the Monge-Ampere equation away from
finitely many points, but contain polyhedral and Y-shaped singular
structures. Along the way we will discuss geometric and applied motivations
for constructing such examples, as well as their connection to a certain
obstacle problem.