清华主页 EN

BIMSA一周学术活动 09.26-09.30

来源: 09-26




Monodromy and period map of the Winger Pencil

BIMSA Topology Seminar

报告人 自云鹏

时 间 15:30-17:00 Mon

地 点 1129B

Zoom 537 192 5549(PW: BIMSA)


We investigate the moduli space of genus 10 curves that are endowed with a faithful action of the icosahedral group $\Acal_5$. We will show among other things that this moduli space essentially consists two copies of the pencil of plane sextics introduced by Winger, an American mathematician, in 1924 with the unique unstable member (a triple conic) replaced by a smooth non-planar curve. We also prove that the Jacobian of a smooth member of the Winger pencil contains the tensor product of an elliptic curve with a certain integral representation of the icosahedral group. We find that the elliptic curve comes with a distinguished point of order $3$, prove that the monodromy on this part of the homology is the full congruence subgroup $\Gamma_1(3)\subset \SL_2(\Zds)$ and subsequently identify the base of the pencil with the associated modular curve. Except those we also observed that the Winger pencil `accounts' for the deformation of the Jacobian of Bring's curve as a principal abelian fourfold with an action of the icosahedral group.

组织者:吴杰, 杨南君, 李京艳


The plectic conjecture over local fields

BIMSA-YMSC Tsinghua Number Theory Seminar

报告人 Siyan Daniel Li-Huerta Harvard University

时 间 10:00-11:00 Tue

地 点 1118

Zoom 293 812 9202(PW: BIMSA)


The étale cohomology of varieties over Q enjoys a Galois action. For Hilbert modular varieties, Nekovář-Scholl observed that this Galois action on the level of cohomology extends to a much larger profinite group: the plectic group. Motivated by applications to higher-rank Euler systems, they conjectured that this extension holds even on the level of complexes, as well as for more general Shimura varieties. We present a proof of the analog of this conjecture for local Shimura varieties. Consequently, we obtain results for the basic locus of global Shimura varieties, after restricting to a decomposition group. The proof crucially uses a mixed-characteristic version of fusion due to Fargues–Scholze.

组织者:Cezar Lupu


Topological Wick rotation and holographic duality

Category and Topological Order Seminar

报告人 孔良 南方科技大学

时 间 13:30-15:00 Tue

地 点 1131

Tencent 607 3645 0351


I will explain a new type of holographic dualities between n+1D topological orders with a chosen boundary condition and nD (potentially gapless) quantum liquids. It is based on the idea of topological Wick rotation, a notion which was first used in arXiv:1705.01087 and was named, emphasized and generalized later in arXiv:1905.04924. I will provide some explicit examples in low dimensions, including the duality between 2+1D toric code model and 1+1D Ising chain and its finite-group generalizations (independently obtained by Freed and Teleman arXiv:1806.00008); that between 2+1D topological orders and 1+1D rational conformal field theories. As a consequence, we immediately obtain the classification of all 1+1D gapped quantum phases, a result which was obtained previously via a very different approach. This classification result generalizes to gapped quantum liquids in higher dimensions (with more general symmetries). I will also discuss some generalizations of this holographic duality and its relation to AdS/CFT duality.



Multiple soliton of the nonlinear Schrodinger equation and its regularity

Integrable Systems Seminar

报告人 张永帅 浙江科技学院

时 间 09:00-10:00 Thu

Tencent 713 979 838


In this talk, we consider the Riemann-Hilbert approach of the nonlinear Schrodinger (NLS) equation. By constructing and solving the Riemann-Hilbert problem with multiple high-order poles, we get the multiple soliton solution of NLS equation. By decomposing the matrix, we prove the regularity of this type soliton.

组织者:王丽, 张国强



BIMSA-Tsinghua Seminar on Machine Learning and Differential Equations

报告人 王涵 北京应用物理与计算数学研究所

时 间 10:00-11:30 Thu

地 点 1129B

Zoom 537 192 5549(PW: BIMSA)





组织者:熊繁升, 杨武岳, 雍稳安, 朱毅


Leibenson's equation on Riemannian manifolds

AMSS-YMSC-BIMSA Joint Seminar on Progress of Topology and Its Applications

报告人 Alexander Grigoryan Universität Bielefeld

时 间 17:00-18:30 Thu

地 点 1120

Zoom 518 868 7656(PW: BIMSA)


We consider on arbitrary Riemannian manifolds the Leibenson equation: $$\partial _{t}u=\Delta _{p}u^{q}.$$ This equation comes from hydrodynamics where it describes filtration of a turbulent compressible liquid in porous medium. Here $u(x,t)$ is the fraction of the volume that the liquid takes in porous medium at time $t$ at point $x$. The parameter $p$ characterizes the turbulence of a flow, while $q$ describes the compressibility of the liquid. We prove that if $p>2$ and $1/(p-1)<q\leq 1$="" then="" solutions="" of="" this="" equation="" have="" finite="" propagation="" speed.="" on="" complete="" manifolds="" with="" non-negative="" ricci="" curvature,="" we="" obtain="" a="" sharp="" rate="" that="" matches="" barenblatt="" solution.


Professor Alexander Grigor'yan received his PhD from Lomonosov Moscow University in 1982. Since then, he worked at the State University of Volgograd and the Institute of Control Sciences in Moscow with receiving his habilitation in 1989. He has been a Humboldt Fellow at Bielefeld University in 1992-93 and a Guest Scholar at Harvard University in 1993/94. After working from lecturer to professor at Imperial College London in 1994-2005, he became a professor at Bielefeld University from 2005. Professor Grigor'yan won a gold medal at International Mathematical Olympiad when he was 17, awarded by the Prize of the Moscow Mathematical Society in 1988, and received the Whitehead Prize of London Mathematical Society in 1997. He was an invited speaker of European Congress of Mathematicians in Barcelona in 2000. Professor Grigor'yan is one of the top experts in geometric analysis on Riemannian manifolds, metric spaces and graphs, with making various important contributions on the topics.




YMSC-BIMSA Quantum Information Seminar in 2022 Spring

报告人 孙晓明 Institute of Computing Technology, CAS

时 间 09:30-12:15 Fri

地 点 JCY-1

Zoom 559 700 6085(PW: BIMSA)






  • BIMSA一周学术活动 09.13-09.16

    公开课/COURSE讨论班/SEMINAR2022-09-13Deep Q-network (DQN) and Q-learningSeminar on Control theory and Nonlinear Filtering报告人 陶飏天择 清华大学数学科学系 博士生时 间 15:00-15:30 Tue地 点 OnlineTencent 735 7908 4302摘要In this report, we will describe how to approximate the optimal action-value function with a neural network, which we call a deep Q-network (DQN). The time difference algorithm ...

  • BIMSA一周学术活动 2022.09.6-2022.09.9

    2022-09-06The discussion on the Out of Africa hypothesis, OOAH and PPA (Progressive Phylogenetic Analysis), that identified the African human populations as paraphyletic Seminar on Bioinformatics报告人 关梦岑 清华大学数学系 博士生时 间 15:00-15:30 TueTencent 801 3489 7723摘要The Out of Africa hypothesis, OOAH, was challenged recently in an extended mtDNA analysis, PPA (Progressive Phylogenetic ...