学术报告
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Completely Monotonic Fredholm DeterminantsIn this talk we discuss some monotonicity questions related to Fredholm matrices and operators. A function $f(x)$ is called completely monotonic if $(-1)^mf^{(m)}(x)>0$. It is known that the expectation of having $m$ eigenvalues of a random Hermitian matrix in an interval is a multiple of $(-1)^{m}$ times the $m$-th derivative of a Fredholm determinant at $/lambda=1$. In this work we extend the positivity to half-real line $(-/infty,1]$, and we also study the completely monotonicity of some special functions which arise as Fredholm determinants.张瑞明 教授 (西北农林科技大学)致远楼101室2019年 5月29日 16:00-17:00
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The Q-Normal Distribution and Q-Hermite PolynomialsWe survey results on q-analogue of the normal distribution and the corresponding orthogonal polynomials.Prof. Mourad E.H. Ismail (University of Central Florida and King Saud University)致远楼101室019年5月29日 14:00-15:00
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Complex Short Pulse and Coupled Complex Short Pulse EquationsIn this talk, we will investigate a complex short pulse equation and its two-component generalization. First, we will derive them starting from Maxwell equations. Then we will study their various soliton solutions such as bright, dark, breather and rogue wave solutions by using Hirota’s bilinear method and Darboux transformation method.冯宝峰 教授 (美国德克萨斯大学大河谷分校)致远楼103室2019年5月29日(周三)15:30-16:30
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Apparent Singularities of D-Finite SystemsWe generalize the notions of ordinary points and singularities from linear ordinary differential equations to D-finite systems. Ordinary points and apparent singularities of a D-finite system are characterized in terms of its formal power series solutions. We also show that apparent singularities can be removed like in the univariate case by adding suitable additional solutions to the system at hand. Several algorithms are presented for removing and detecting apparent singularities. In addition, an algorithm is given for computing formal power series solutions of a D-finite system at apparent singularities. This is a joint work with Manuel Kauers, Ziming Li and Yi Zhang.陈绍示 副研究员 (中国科学院 数学与系统科学研究院)致远楼103室2019年5月24日14:00-15:00
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On the Existence of Conic Kahler-Einstien MetricLog Fano manifold are generalization of Fano manifolds, and the canonical metrics on them are conic Kahler-Einstein metrics. I will talk about the existence of such metrics on log K-polystable log Fano manifolds.王枫 副教授 (浙江大学)致远楼101室2019年5月23日14:00-16:00
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Asymptotic Spreading of Interacting Species with Multiple FrontsWe establish spreading properties of the Lotka-Volterra competition-diffusion system. When the initial data vanish on a right half-line, we show that there are two successive invasions. We derive the formulas of the exact spreading speeds and prove the convergence to homogeneous equilibrium states in between the invasion fronts. Our method is inspired by the geometric optics approach for Fisher-KPP equation due to the work of Freidlin, and that of Evans and Souganidis. Our main result settles an open question raised by Shigesada and Kawasaki in 1997, and shows that one of the species spreads to the right with a speed which is linearly, but non-locally, determined.King-Yeung Lam assistant professor (Ohio State University)致远楼101室2019年5月22日上午10:00-11:00
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A Fast Proximal Point Method for Computing Exact Wasserstein DistanceWasserstein distance plays increasingly important roles in machine learning, stochastic programming and image processing. Major efforts have been under way to address its high computational complexity, some leading to approximate or regularized variations such as Sinkhorn distance. However, as we will demonstrate, regularized variations with large regularization parameter will degradate the performance in several important machine learning applications, and small regularization parameter will fail due to numerical stability issues with existing algorithms. We address this challenge by developing an Inexact Proximal point method for exact Optimal Transport problem (IPOT) with the proximal operator approximately evaluated at each iteration using projections to the probability simplex. The algorithm (a) converges to exact Wasserstein distance with theoretical guarantee and robust regularization parameter selection,王祥丰 副教授 (华东师范大学 计算机科学与软件工程学院)致远楼103室2019年5月21日下午2:00-3:00
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A Supplement to Jiang's Limit LawsLet be an array of i.i.d. random variables, and let be a sequence of positive integers such that is bounded away from 0 and . The sample correlation matrix is generated from , , such that is the Pearson correlation coefficient between and . In this talk, we provide a supplement to Jiang's asymptotic distribution of the largest entry . We show that, for given nondecreasing function with ,there exists an array of symmetric i.i.d. random variables such that and, for some subsequence of , almost surely; does not exist almost surely; , ,and does not convergence in distribution, whereProfessor Deli LI (加拿大湖首大学 数学科学系)致远楼101室2019年5月20日(周一)上午9:30