Colloquia & Seminars Archives - Page 146 of 153

Seminars: Colloquia & Seminars

Date
Time
Venue

Speaker
Affiliation
Title of Talk

18 Apr 2019
16:00
S17 #05-12 SR4

Tian Fangyang
National University of Singapore
Laplacian Equations from a Representation-Theoretic Point of View

Laplacian Equations from a Representation-Theoretic Point of View

Date/Time : 18 Apr 2019 16:00
Venue : S17 #05-12 SR4
Speaker : Tian Fangyang, National University of Singapore

Date/Time:18 Apr 2019 16:00 Venue: S17 #05-12 SR4 Speaker: Tian Fangyang, National University of Singapore Laplacian Equations from a Representation-Theoretic Point of View The classical Laplacian equation and wave equation are the basic examples of second order PDE. The fundamental solutions of them, which have been well studied, play an important role in the theory of these equations. A nice feature of these two equations is that the differential operator is invariant under certain classical group, hence one may expect a representation theoretic explanation of these equations. The (indefinite) Laplacian equations serve as a natural generalization of classical Laplacian equation and wave equation. In this talk, I will follow Howe and Tan’s exposition to discuss the (indefinite) Laplacian equation from a representation-theoretic point of view. We will cover some basic representation theory of (sl(2,R), so(2))-module, Weil representation of \tilde{SL(2,R)}, and the fundamental solutions of the indefinite Laplacian Equation. Add to calendar:

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17 Apr 2019
15:00
S17 #05-11 SR5

Oscar Garcia-Prada
ICMAT, Madrid
Higgs bundles and higher Teichmüller spaces

Higgs bundles and higher Teichmüller spaces

Date/Time : 17 Apr 2019 15:00
Venue : S17 #05-11 SR5
Speaker : Oscar Garcia-Prada , ICMAT, Madrid

Date/Time:17 Apr 2019 15:00 Venue: S17 #05-11 SR5 Speaker: Oscar Garcia-Prada, ICMAT, Madrid Higgs bundles and higher Teichmüller spaces Some connected components of a moduli space are mundane in the sense that they are distinguished only by obvious topological invariants or have no special characteristics. Others are more alluring and unusual either because they are not detected by primary invariants, or because they have special geometric significance, or both. In this talk, I will describe examples of such special components in moduli spaces of G-Higgs bundles on closed Riemann surfaces or, equivalently, moduli spaces of surface group representations into a semisimple Lie group G. These special components are related to higher Teichmüller theory and the notion of positivity for Anosov representations recently introduced by Guichard and Wienhard. Add to calendar:

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17 Apr 2019
15:00
S17 #04-04 SR3

Zeng Fanhai
National University of Singapore
Fast time-stepping method for fractional integral and derivative operators

Fast time-stepping method for fractional integral and derivative operators

Date/Time : 17 Apr 2019 15:00
Venue : S17 #04-04 SR3
Speaker : Zeng Fanhai, National University of Singapore

Date/Time:17 Apr 2019 15:00 Venue: S17 #04-04 SR3 Speaker: Zeng Fanhai, National University of Singapore Fast time-stepping method for fractional integral and derivative operators We develop two fast time-stepping methods with linear complexity to calculate the discrete convolution for the approximation of the fractional integral and derivative operators. The effectiveness of the fast methods are verified through a series of numerical examples for long-time integration, including a numerical study of a fractional reaction-diffusion model. Add to calendar:

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17 Apr 2019
17:00
S17 #04-06 SR1

Liu Tianyu

Arithmetic algorithm of surreal numbers

Arithmetic algorithm of surreal numbers

Date/Time : 17 Apr 2019 17:00
Venue : S17 #04-06 SR1
Speaker : Liu Tianyu,

Date/Time:17 Apr 2019 17:00 Venue: S17 #04-06 SR1 Speaker: Liu Tianyu Arithmetic algorithm of surreal numbers The surreal number system is a totally ordered proper class containing the real numbers as well as infinite and infinitesimal numbers. A surreal number is sometimes defined as a function from an initial segment of the ordinals into the set $(+,-)$, usually leads to an infinite sign sequence. It can also be expressed uniquely in a normal form, as $\sum_{i<\alpha} \omega^{a_i}r_i$. In this talk I will present some algorithms for addition, multiplication and division on the real field. Besides, we will cover the normal form and sign sequence of surreal numbers, which will be crucial for arithmetic algorithm of surreal numbers of length $>\omega$. Add to calendar:

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15 Apr 2019
17:00
S17 #06-11

Lin Wayne, Lu Jianlong, Lim Zhan Feng, An X
National University of Singapore
Black Hole Quartet

Black Hole Quartet

Date/Time : 15 Apr 2019 17:00
Venue : S17 #06-11
Speaker : Lin Wayne, Lu Jianlong, Lim Zhan Feng, An X, National University of Singapore

Date/Time:15 Apr 2019 17:00 Venue: S17 #06-11 Speaker: Lin Wayne, Lu Jianlong, Lim Zhan Feng, An X, National University of Singapore Black Hole Quartet We will present four 15-minute introductory talks on black holes: i) An introduction to black hole (by Lin Wayne) ii) Frozen star paradox (by Lu Jianlong) iii) Gravitational collapse under spherical symmetry (by Lim Zhan Feng) iv) What’s inside a black hole? (by An Xinliang) Add to calendar:

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15 Apr 2019
16:00
S17 #06-11

Deng Changsong
Wuhan University
Space and Time-Fractional Equations: a Random Time-Change Approach

Space and Time-Fractional Equations: a Random Time-Change Approach

Date/Time : 15 Apr 2019 16:00
Venue : S17 #06-11
Speaker : Deng Changsong, Wuhan University

Date/Time:15 Apr 2019 16:00 Venue: S17 #06-11 Speaker: Deng Changsong, Wuhan University Space and Time-Fractional Equations: a Random Time-Change Approach I will talk about a class of non-local equations with fractional operators in time and space from the point of view of the probability theory. In particular, we establish the exact asymptotic formulas for the fundamental solution to the $n$-dimensional fractional heat equations in both time and space. Add to calendar:

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11 Apr 2019
16:00
S17 #05-12 SR4

Jiang Meiyue
Peking University
Q-CURVATURE EQUATION IN DIMENSION 1

Q-CURVATURE EQUATION IN DIMENSION 1

Date/Time : 11 Apr 2019 16:00
Venue : S17 #05-12 SR4
Speaker : Jiang Meiyue, Peking University

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10 Apr 2019
15:00
S17 #05-11 SR5

Wang Dong
National University of Singapore
Phase transition related to Lyapunov exponents in the model of product of complex Ginibre matrices

Phase transition related to Lyapunov exponents in the model of product of complex Ginibre matrices

Date/Time : 10 Apr 2019 15:00
Venue : S17 #05-11 SR5
Speaker : Wang Dong , National University of Singapore

Date/Time:10 Apr 2019 15:00 Venue: S17 #05-11 SR5 Speaker: Wang Dong, National University of Singapore Phase transition related to Lyapunov exponents in the model of product of complex Ginibre matrices In this talk we consider the product of M independent complex Ginibre matrices, each of size N x N. The singular values of the product random matrix as M goes to infinity, under proper scaling, are Lyapunov exponents of a toy dynamical system model. In this talk we consider the model as (1) M goes to infinity and N is fixed, (2) N goes to infinity and M is fixed, or (3) M, N both goes to infinity, and find the behaviour of the largest singular eigenvalues. We observe a phase transition as M/N is O(1). Add to calendar:

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10 Apr 2019
14:00
S17 #05-11 SR5

Li Yunzhe
National University of Singapore
Uniqueness of billiards coding in polygon

Uniqueness of billiards coding in polygon

Date/Time : 10 Apr 2019 14:00
Venue : S17 #05-11 SR5
Speaker : Li Yunzhe, National University of Singapore

Date/Time:10 Apr 2019 14:00 Venue: S17 #05-11 SR5 Speaker: Li Yunzhe, National University of Singapore Uniqueness of billiards coding in polygon The study of mathematical billiards is a rich subject in dynamical systems. It describes the frictionless motion of a mass point in a domain with elastic reflection on the boundary. Among many other variations of mathematical billiards, polygonal billiards concerns the billiard problem in a two dimensional polygonal domain. One particular strategy to study polygonal billiards is to encode the trajectory of a billiard by the sequence of sides of the polygonal domain hit by the billiard along its trajectory. Several questions could be asked regarding this encoding and its relations with the billiard. Especially, we may want to know to what extend this encoding determines the physical trajectory of the billiard in the polygonal domain? In 1993, it has been proven by G. Galperin, T. Krüger and S. Troubetzkoy that for a non periodic trajectory in a simply connected polygon the encoding uniquely determines the physical trajectory. We aims to generalise this result to a wider class of polygons which are not necessarily simply connected but contain a finite number of holes such that the holes have non zero minimal diameter. This result was proven in a research project in 2018 at Aix-Marseille université under the supervision of S. Troubetzkoy. Add to calendar:

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