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报告题目: 量子力学的完备性与实在性
报 告 人: 陈泽乾 研究员,中科院武汉物理与数学研究所
时间地点: 2013年10月9日(星期三)下午4:00 思源楼703室
报告摘要:

In this talk, we will report a proof for the completeness of von Neumann's axiomatic system on quantum mechanics in the sense that, under the assumption of von Neumann's measurement axiom, no extension of quantum theory can give more information about the outcomes of future measurements than quantum theory itself. The proof is based on Gleason's theorem. Our result sheds new light on the foundations of quantum mechanics, as well as applications to tasks that exploit the inherent randomness in quantum theory, such as quantum computing. This is a joint work with A. Montina 【Zeqian Chen, A. Montina, Measurement contextuality is implied by macroscopic realism, Physical Review A 83 , 042110 (2011)】.

报告题目: Construction of SLE and CLE from Poisson point process of Brownian paths
报 告 人: Dr. Hao Wu, University Paris Sud and MIT
时间地点: 2013年7月29日(星期一)下午2:30 思源楼712室
报告摘要:

SLE (Stochastic Loewner Evolution) processes are introduced by Oded Schramm in 1999 as candidates for the scaling limits of discrete models in two dimensions. They are usually presented as a random curve generated via Loewner evolution equations. In our talk, we give another construction of SLE curves from Poisson point process of Brownian paths. We first introduce SLE and CLE from the point of view of discrete models where the initial motivation came from. Then we construct SLE8=3 curves from Poisson Point Process of Brownian excursions which is derived by Lawler,Schramm and Werner in [LSW03]. Third, we construct CLEk from Poisson point process of Brownian loops derived by Sheffield and Werner in [SW12]. Finally,we construct SLEk from the union of Poisson point process of Brownian excursions and Poisson point process of Brownian loops. And this is the main result of [WW13] by Werner and Wu.

[LSW03] Gregory Lawler, Oded Schramm, and Wendelin Werner. Conformal restriction: the chordal case. J. Amer. Math. Soc., 16(4):917–955 (electronic),2003.
[SW12] Scott Sheffield and Wendelin Werner. Conformal loop ensembles: the Markovian characterization and the loop-soup construction. Ann. of Math. (2), 176(3):1827–1917, 2012.
[WW13] Wendelin Werner and Hao Wu. From cle(nkappa) to sle(nkappa,nrho)’s. Electron. J. Probab., 18:no. 36, 1–20, 2013.

报告题目: Algorithmic Aspects on Power Domination Problem of Graphs
报 告 人: Prof. Changhong Lu, Department of Mathematics, East China Normal University
时间地点: 2013年8月1日(星期四)上午10:00 思源楼712室
报告摘要:

The power system monitoring problem asks for as few as possible measurement devices to be put in an electric power system. The problem has a graph theory model involving power dominating set in graphs. Let G be a graph. A set S of vertices is a power dominating set of G if and only if all vertices of G have a message either by Observation Rule 1 (OR1) initially or by bservation Rule 2 (OR2) recursively.

OR1: A vertex v in S sends a message to itself and all its neighbors. We say v observes itself and all its neighbors.OR2: If an observed vertex v has only one unobserved neighbor u then v will send a message to u. We say v observes u.

In this talk, we present simplified linear-time algorithms for this problem in trees and block graphs.

报告题目: Submodular Optimization: A Tutorial
报 告 人: Prof. Donglei Du, University of New Brunswich, Canada
时间地点: 2013年8月16日(星期五)下午4:00 思源楼1013室
报告摘要:

ISubmodular optimization is an important topic incombinatorial optimization. In this tutorial, we will review extant literature with a focus on recent development on approximation algorithms for submodular optimization.

Prof. Donglei Du received his MS degree from Shangdong University, his PhD degree in Operations Research in Institute of Applied Math, CAS, and his PhD degree in Computer Science from University of Texas at Dallas. His research interests include Combinatorial Optimization, Supply Chain Management, Algorithmic Game Theory, Robust Optimization and its Applications.

报告题目: Some Efficient Domain Decomposition Methods for a Class of Inverse Problems
报 告 人: Professor Jun Zou,Dept of Math, Chinese University of Hong Kong
时间地点: 2013年8月15日(星期四)上午10:030 思源楼712室
报告摘要:

In this talk we shall present several new domain decomposition methods for solving some linear and nonlinear inverse problems. The motivations and derivations of the methods will be discussed, and numerical experiments will be demonstrated.

报告题目: NSF Center for Research on Complex Networks and its Research in Wireless Sensor Networks

报 告 人: Prof. Wei LI,Dept of Computer Science, Texas Southern Univ., USA
时间地点: 2013年6月7日(星期五)上午10:00 思源楼712室
报告摘要:

Prof. Li plans to introduce the research topics of NSF Center for Research on Complex Networks, explore the integration of different research projects in energy efficient wireless sensor networks, urban transportation environmental networks, and distributed computational networks, as well as explain their importance to the science, technology, engineering and mathematics (STEM) education and technology transfer. In particularly, the speaker will address some of the specific research in wireless networks and wireless sensor networks.

Prof. Li received his PhD at Institute of Applied Mathematics, Chinese Academy of Sciences in 1994. Currently, he is the director of NSF Center for Research on Complex Networks (cs.tsu.edu/crest/) and Interim Chair of Department of Computer Science (cs.tsu.edu/), Texas Southern University, Houston, USA.

报告题目: On Judicious Bisections of Graphs
报 告 人: Prof.Xingxing Yu, Professor of Mathematics Georgia Institute of Technology
时间地点: 2013年6月5日(星期三)上午10:00 思源楼712室
报告摘要:

A bisection of a graph G is a bipartition S1,S2 of V(G) such that ||S1|-|S2||<=1.It is NP-hard to find a bisection S1,S2 maximizing e(S1,S2) (repectively, minimizing max{e(S1),e(S2)}, where e(S1,S2) denotes the number of edges from S1 to S2, and e(Si) denotes the number of edges of G with both ends in Si. There has been extensive research on bisections from algorithmic point of view, but very few extremal results are known. Bollob'{a}s and Scott conjectured that if G is a graph with m edges and minimum degree at least 2 then G admits a bisection S1,S2 such that e(Si)<=m/3 for i=1,2. In this paper, we confirm this conjecture and show that any extremal graph is a disjoint union of triangles.

报告题目: The Bandpass problem
报 告 人: Prof. Guohui LIN,Dept of Computing Science, University of Alberta
时间地点: 2013年5月30日(星期四)上午10:00 思源楼712室
报告摘要: The general Bandpass-B problem is NP-hard and can be approximated by a reduction into the weighted B-set packing problem, with a worst case performance ratio of O(B^2). When B = 2, a maximum weight matching gives a 2-approximation to the problem. In this talk, we call the Bandpass-2 problem simply the Bandpass problem. The Bandpass problem can be viewed as a variation of the maximum traveling salesman problem, in which the edge weights are dynamic rather than given at the front. We present a 426/227-approximation algorithm for the problem. Such an improved approximation is built on an intrinsic structural property proven for the optimal solution and several novel schemes to partition a b-matching into desired matchings.
报告题目: Approximating the minimum independent dominating set
报 告 人: Prof. Guohui LIN,Dept of Computing Science, University of Alberta
时间地点: 2013年5月30日(星期四)上午9:00 思源楼712室
报告摘要: We investigate the minimum independent dominating set in perturbed graphs g(G, p) of input graph G = (V, E), obtained by negating the existence of edges independently with a probability p > 0. The minimum independent dominating set (MIDS) problem does not admit a polynomial running time approximation algorithm with worst-case performance ratio of n^{1 - e} for any e > 0. We prove that the size of the minimum independent dominating set in g(G, p), denoted as i(g(G, p)), is asymptotically almost surely in Theta(log |V|). Furthermore, we show that the probability of i(g(G, p)) >= sqrt{4|V|/p} is no more than 2^{-|V|}, and present a simple greedy algorithm of proven worst-case performance ratio sqrt{4|V|/p} and with polynomial expected running time.
报告题目: Approximating the minimum independent dominating set
报 告 人: Prof. Guoli Ding, Dept of Math., Louisiana State University, USA
时间地点: 2013年5月28日(星期二)上午10:00 思源楼703室
报告摘要:

Projective planar graphs are characterized by 35 forbidden minors. In this talk we explain how to characterize large well connected projective graphs by only 6 forbidden minors.

Prof. Guoli Ding received his MS degree from Institute of System Science, CAS, Beijing, and his PhD degree in Operations Research from Rutgers University, New Jersey. Since 2001, he is a professor at Department of Mathematics., Louisiana State University. His research interests include graph theory and combinatorial optimization.

报告题目: An RNA Network for Cancer Metastasis
报 告 人: Yi Xing, Associate Professor, University of California, Los Angeles
时间地点: 2013年5月20日(星期一)上午10:00 思源楼1013室
报告摘要: The epithelial-mesenchymal transition (EMT), characterized by the loss of cell-cell adhesion in epithelial cells and the acquisition of motile and invasive properties in mesenchymal cells, is one key mechanism by which tumors of epithelial origin acquire the capability to undergo tissue invasion and metastasis. An underlying principle of EMT is that global changes in the gene regulatory network drive transformation in cell phenotype during this process. While recent studies have characterized the transcriptional network of EMT, the roles of post-transcriptional processes such as alternative splicing and polyadenylation are poorly understood. In this talk, I will introduce computational and statistical methods we developed for global analysis of post-transcriptional gene regulation using high-throughput sequencing technologies. Through the use of integrated genomic, computational, and molecular approaches, we have elucidated the genome-wide landscape of alternative splicing during EMT. This cell-type-specific splicing network is globally switched in in vitro and in vivo models of cancer invasion and metastasis, and represents a robust molecular signature of cancer cells with invasive properties and aggressive phenotypes. Our study provides a comprehensive picture of an extensive EMT-regulated post-transcriptional RNA network in development and cancer.
报告题目: Strong Oracle Optimality of Folded Concave Penalized Estimation
报 告 人: Jianqing Fan, Department of Operations Research and Financial Engineering, Princeton University
时间地点: 2013年5月10日(星期五)下午3:00 思源楼712室
报告摘要: Folded concave penalization methods have been shown to enjoy the strong oracle property for high-dimensional sparse estimation. However, a folded concave penalization problem usually has multiple local solutions and the oracle property is established only for one of the unknown local solutions. A challenging fundamental issue still remains that it is not clear whether the local optimal solution computed by a given optimization algorithm possesses those nice theoretical properties. To close this important theoretical gap in over a decade, we provide a unified theory to show explicitly how to obtain the oracle solution using the local linear approximation algorithm. For a folded concave penalized estimation problem, we show that as long as the problem is localizable and the oracle estimator is well behaved, we can obtain the oracle estimator by using the one-step local linear approximation. In addition, once the oracle estimator is obtained, the local linear approximation algorithm converges, namely produces the same estimator in the next iteration. We show that the LASSO is a good initial estimator, which produces the oracle estimator using the one-step LLA algorithm for folded concave penalization methods. This is demonstrated by using three classical sparse estimation problems, namely, the sparse linear regression, the sparse logistic regression and the sparse precision matrix estimation, and illustrates the power of combining the LASSO and SCAD to solve sparse inartistical estimation problem. (joint work with Lingzhou Xue and Hui Zou).
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