In these talks, I will briefly survey some development of results on hyperbolic Dehn fillings. I will discuss works of I.Agol and M.Lackenby related to bounds on exceptional Dehn fillings of cusped hyperbolic 3-manifolds.

Cone spherical metrics are constant curvature +1 conformal metrics with finitely many cone singularities on compact Riemann surfaces. Their existence has been an open problem since 1980s. The speaker will talk about the recent progresses on this problem joint with Qing Chen, Yu Feng, Bo Li, Lingguang Li, Yiqian Shi, Jijian Song and Yingyi Wu.

A modular tensor category is pointed if every simple object is a simple current. We show that any pointed modular tensor category is equivalent to the module category of a lattice vertex operator algebra. Moreover, if the pointed modular tensor category C is the module category of a twisted Drinfeld double associated to a finite abelian group G and a 3-cocycle with coefficients in U(1), then there exists a selfdual positive definite even lattice L such that G can be realized an automorphism group of lattice vertex operator algebra $V_L,$ $V_L^G$ is also a lattice vertex operator algebra and C is equivalent to the module category of $V_L^G.$ This is a joint work with S. Ng and L. Ren.

Let V be a vertex operator superalgebra and G a finite automorphism group of V containing the canonical automorphism such that V^G is regular.We classify the irreducible V^G -modules appearing in twisted V -modules and prove that these are all the irreducible V^G -modules. Moreover, the quantum dimensions of irreducible V^G -modules are determined, a global dimension formula for V in terms of twisted modules is obtained and a super quantum Galois theory is established. In addition, the S-matrix of V^G is computed.

I will discuss the result on the non-uniqueness of solutions to the dual Minkowski problem. In particular we show that for the problem with constant right hand side, when $q>2n$ the solution is non-unique.

In this talk, we talk about the regularity of the free boundary in the Monge-Ampere obstacle problem. This is a joint work with Prof. Tang Lan and Prof. Wang Xu-Jia.

In this lecture, we present practical and provably secure (authenticated) key exchange protocol and password authenticated key exchange protocol, which are based on the learning with errors problems. These protocols are conceptually simple and have strong provable security properties. This type of new constructions were started in 2011-2012. These protocols are shown indeed practical. We will explain that all the existing LWE based key exchanges are variants of this fundamental design. In addition, we will explain some issues with key reuse and how to use the signal function invented for KE for authentication schemes.

In this talk, I will talk about our recent results for the well-posedness of the 3D incompressible Hall-magneto-hydrodynamic system (Hall-MHD). First, we provide an elementary proof of a global well-posedness result for small data with critical Sobolev regularity, in the spirit of Fujita-Kato’s theorem for the Navier-Stokes equations. Next, we present the long-time asymptotics of global (possibly large) solutions of the Hall-MHD system that are in the Fujita-Kato regularity class. A weak-strong uniqueness statement is also presented. Finally, we consider the so-called 2.5D flows for the Hall-MHD system (that is 3D flows independent of the vertical variable), and establish a global existence of strong solutions, assuming only that the initial magnetic field is small.