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Academy of Mathematics and Systems Science, CAS Colloquia & Seminars：Direct sampling method to inverse wave-number-dependent source problems: determination of the support of a stationary source
反波数 相关源问题 直接采样 固定源
2023/11/29
This talk is concerned with a direct sampling method for imaging the support of a frequency-dependent source term embedded in a homogeneous and isotropic medium. The source term is given by the Fourie...
Academy of Mathematics and Systems Science, CAS Colloquia & Seminars：Solving hidden number problem with lattice sieving
晶格筛分 隐数问题 格约简算法
2023/4/28
Lattice reduction algorithms have been proved to be one of the most powerful and versatile tools in public key cryptanalysis. In this talk, we primarily concentrate on lattice attacks against (EC)DSA ...
Academy of Mathematics and Systems Science, CAS Colloquia & Seminars：Number of rational points of difference varieties in finite difference fields
有限差分域 差分簇 有理点数
2023/4/13
A difference field is a field with a distinguished automorphism. Automorphisms of a finite field are powers of the Frobenius map. In this talk, I will discuss how to estimate the number of rational po...
Academy of Mathematics and Systems Science, CAS Colloquia & Seminars：Learning Quantum Observables of Low Degrees from a Logarithmic Number of Random Queries
对数 随机查询 低次量子 可观察量
2023/4/14
A fundamental problem from computational learning theory is to well-reconstruct an unknown function on the discrete hypercubes. One classical result of this problem for the random query model is the l...
Academy of Mathematics and Systems Science, CAS Colloquia & Seminars：Almost periodic function and rotation number of the Schrodinger operator
薛定谔算子 几乎周期函数 旋转数
2023/4/25
The concept of almost periodic functions is due to H. Bohr. The concept of rotation number is due to H. Poincaré. The Schr?dinger operator is named after E. Schr?dinger. I will present our work relate...
Academy of Mathematics and Systems Science, CAS Colloquia & Seminars：On the Turán number of theta graphs
θ图 图兰数 图论
2023/4/26
Turán-type problem may be one of central problems in extremal graph theory. Particularly, the Turán number of a cycle attracts much attention. In this talk, we introduce a terminology, that is, theta ...
Academy of Mathematics and Systems Science, CAS Colloquia & Seminars：Proper orientations and proper orientation number
正确取向数 MAD（G） 图论
2023/4/27
The proper orientation number \Vec{\chi}(G) of a graph G is the minimum k such that there exists an orientation of the edges of G with all vertex-outdegrees at most k and such that for any adjacent ve...
Academy of Mathematics and Systems Science, CAS Colloquia & Seminars：Markov Chains and θ-Congruent Number Problem
马尔可夫链 θ-同余数 θ-全等数分布
2023/5/10
A positive integer n is called a θ-congruent number if n sin θ is the area of a triangle with rational side lengths and with an angle θ. Markov chains play a key role in the study of the distribution ...
Number of Published Science and Engineering Articles Flattens, But U.S. Influence Remains Strong（图）
Published Science 出版业 Engineering 工程学
2007/7/24
July 19, 2007，A new National Science Foundation (NSF) report finds the number of U.S. science and engineering (S&E) articles in major peer-reviewed journals flattened in the 1990s, after more than two...
14 May 2007，Close to 1000 grade nine and ten high school students will descend on University of Southern Queensland this week (Tuesday 15-18 May 2007), for the Science and Regional Challenge.
Record Number of Countries Contribute Record Amount to United Nations Population Fund in 2006
reproductive health HIV prevention
2007/1/30
15 January 2007,UNITED NATIONS, New York — In 2006, 180 countries around the world contributed a total of $360 million to the regular resources of UNFPA, the United Nations Population Fund. This was t...