Date/Time : 09 Oct 2019 14:00
Venue : S17 #04-06 SR1
Speaker : Hirofumi Osada, Kyushu University

I talk homogenization of diffusion in the two-dimensional Euclid space in a periodic Coulomb environment. That is, I consider a periodic point process in the plane. The diffusion has the repulsive interaction with the two-dimensional Coulomb potential with inverse temperature $\beta$ to each particle in the periodic point process. We first prove that the diffusion is diffusive with non-degenerated effective diffusion constant $\gamma$. We then remove one particle from the environment and consider the diffusive scaling limit of the diffusion. Then its new effective constant depends on inverse temperature $\beta$. It has a phase transition whose critical point is given explicitly in terms of the first effective diffusion constant $\gamma$ of the periodic homogenization problem. Using this result, we present explicit bounds for the critical point of the self-diffusion matrices of the strict two-dimensional Coulomb interacting Brownian motions for inverse temperature $\beta$. Moreover, we discuss the case d-dimensional case with d \ge 3.

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Date/Time : 08 Oct 2019 14:00
Venue : S17 #05-11 SR5
Speaker : Chen Xiaoyang , Tongji University

Date/Time:08 Oct 2019 14:00 Venue: S17 #05-11 SR5 Speaker: Chen Xiaoyang, Tongji University Vanishing theorems of Morse-Novikov cohomology We will discuss basic properties of Morse-Novikov cohomology and some vanishing theorems related to almost nonnegative curvature. Add to calendar: 

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Date/Time : 03 Oct 2019 17:00
Venue : S17 #06-11
Speaker : Dilip Raghavan, National University of Singapore

Date/Time:03 Oct 2019 17:00 Venue: S17 #06-11 Speaker: Dilip Raghavan, National University of Singapore All ultrafilters in L(R)[U] are rapid We will show that all ultrafilters in the model L(R)[U] are rapid. This is joint work with Paul Larson. Add to calendar: 

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Date/Time : 02 Oct 2019 10:00
Venue : S16 #03-09
Speaker : Bao Huanchen, National University of Singapore

Date/Time:02 Oct 2019 10:00 Venue: S16 #03-09 Speaker: Bao Huanchen, National University of Singapore The m=2 amplituhedron An amplituhedron (defined in terms of totally nonnegative Grassmannians) is a geometric structure introduced in 2013 by two physicists Nima Arkani-Hamed and Jaroslav Trnka. In this talk I shall explain the triangulation of the m=2 amplituhedron. This is joint work with Xuhua He. Add to calendar: 

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Date/Time : 02 Oct 2019 16:00
Venue : S17 #05-11 SR5
Speaker : SHAO Sihong, Peking University

Date/Time:02 Oct 2019 16:00 Venue: S17 #05-11 SR5 Speaker: SHAO Sihong, Peking University Lovász extension and graph cut A firm bridge between discrete data world and continuous math field should be tremendously helpful in data analysis. Along this direction, the Lovász extension provides a both explicit and equivalent continuous optimization problem for a discrete optimization problem, for instance, the Cheeger cut problem. In this talk, we report a set- pair Lovász extension which provides not only an answer to the dual Cheeger cut, anti-Cheeger cut, and max 3-cut problems, all of which cannot be handled by the Lovász extension, but also works for the Cheeger cut and maxcut problems. In particular, the set-pair Lovász extension enlarges the feasible region of resulting equivalent continuous optimization problems from a half space (resulted from the Lovász extension ) to the entire space for the Cheeger cut and maxcut problems. On the other hand, it provides new possibilities for designing continuous optimization algorithms for combination problems on the practical side, too. As an illustration, we propose a simple continuous iterative algorithm for the maxcut problem which converges to a local optimum in finite steps. Here ‘simple’ means the inner subproblem is solved analytically and thus no optimization solver is called. Preliminary results on G-set demonstrate that the ratio between the best cut values achieved by the simple algorithm without any local breakout techniques and the best known ones is of at least $0.986$. Add to calendar: 

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Date/Time : 02 Oct 2019 16:00
Venue : S16 #03-09
Speaker : Yin Silu, Hangzhou Normal University

Date/Time:02 Oct 2019 16:00 Venue: S16 #03-09 Speaker: Yin Silu, Hangzhou Normal University Global well-posedness of elastodynamics In this talk, I will present some classical theory of elastic waves. The motion of elasticity is a wave system with multiple speeds, so Lorentz invariant is absent. For incompressible isotropic elasticity with constant density in 3D, the Cauchy problem with small initial datum were studied by a series work of Sideris and Thomases. We studied the inhomogeneous case in Lagrangian coordinate under the assumption that the density is a small perturbation around a constant state. This is a joint work with Xiufang Cui. Add to calendar: 

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Date/Time : 25 Sep 2019 10:00
Venue : S16 #03-09
Speaker : Max Gurevich, National University of Singapore

Date/Time:25 Sep 2019 10:00 Venue: S16 #03-09 Speaker: Max Gurevich, National University of Singapore Robinson-Schensted-Knuth correspondence at the service of p-adic GL(n) In a joint work with Erez Lapid we constructed a new class of representations based on applying the RSK algorithm on Zelevinski’s multisegments. Those constructions have the potential to be an alternative to the commonly used basis of standard representations. Intriguingly, this class also turned out to categorify a 45-year-old development in invariant theory: The Rota basis of standard bitableaux. I will talk about this classical theme and its relation to representations of p-adic GL(n), as well the expected properties of our new class. Add to calendar: 

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Date/Time : 25 Sep 2019 16:00
Venue : S17 #06-11
Speaker : Foo Wei Guo , Chinese Academy of Sciences

Date/Time:25 Sep 2019 16:00 Venue: S17 #06-11 Speaker: Foo Wei Guo, Chinese Academy of Sciences Equivalence problem of CR real hypersurfaces with uniform Levi rank: the degenerate case In this talk, we discuss about the Cartan’s equivalence problem of 5-dimensional CR real hypersurfaces of constant Levi rank 1, and which are 2-non-degenerate. An important homogeneous model is the tube over the future light cone which has 10 dimensional Lie algebra of infinitesimal CR automorphisms, isomorphic to so(3,2). In 2015, Samuel Pocchiola in his joint work with Joel Merker produced 2 primary invariants which characterise such a homogeneous model. If time permits, we might discuss about the geometry of PDE for this problem which has relation to third order ODE and the Einstein-Weyl geometry. Add to calendar: 

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Date/Time : 18 Sep 2019 16:00
Venue : S16 #03-09
Speaker : Chen Haoyang, Fudan University

Date/Time:18 Sep 2019 16:00 Venue: S16 #03-09 Speaker: Chen Haoyang, Fudan University Global regularity for Einstein-Klein-Gordon system with $U(1) \times \mathbb{R}$ isometry group In this paper we prove the global regularity of the 3+1 dimensional Einstein-Klein-Gordon system with a $U(1)\times \mathbb{R}$ isometry group. We reduce the Cauchy problem of the Einstein-Klein-Gordon system to a 2+1 dimensional system. We prove that the energy of this system cannot concentrate near the first possible singularity, and hence is small. Then, we show that the global regularity holds for the reduced 2+1 dimensional system with initial data of small energy. Add to calendar: 

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