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18:17, 17 April 2023 Etone talk contribs created page 概率论与数理统计 (Spring 2023)/Weierstrass Approximation Theorem (Created page with "[https://en.wikipedia.org/wiki/Stone%E2%80%93Weierstrass_theorem '''魏尔施特拉斯逼近定理''']（'''Weierstrass Approximation Theorem'''）陈述了：闭区间上的连续函数总可以用多项式一致逼近。 {{Theorem|魏尔施特拉斯逼近定理| :设<math>f:[a,b]\to\mathbb{R}</math>为定义在实数区间<math>[a,b]</math>上的连续实值函数。对每个<math>\epsilon>0</math>，存在一个多项式 <math>p</math> 使得对于 <math>[a,b]</math>...")
14:58, 17 April 2023 Etone talk contribs created page 概率论与数理统计 (Spring 2023)/Two-point sampling (Created page with "= 利用线性同余方程构造两两独立的随机变量 = 令<math>p</math>为一质数。考虑模<math>p</math>余数构成的集合<math>[p]=\{0,1,\ldots,p-1\}=\mathbb{Z}_p</math>。众所周知，当<math>p</math>为质数时，<math>\mathbb{Z}_p</math>为对模<math>p</math>加法和乘法运算闭合的'''有限域'''。我们现在构造一系列值域为<math>[p]</math>的'''两两独立'''（'''pairwise Independent'''）且'''均匀分布'''（'''uniforml...")
11:36, 13 April 2023 Etone talk contribs created page 组合数学 (Fall 2023)/Cayley's formula (Created page with "== Cayley's Formula == We now present a theorem of the number of labeled trees on a fixed number of vertices. It is due to [http://en.wikipedia.org/wiki/Arthur_Cayley Cayley] in 1889. The theorem is often referred by the name [http://en.wikipedia.org/wiki/Cayley's_formula Cayley's formula]. {{Theorem|Cayley's formula for trees| : There are <math>n^{n-2}</math> different trees on <math>n</math> distinct vertices. }} The theorem has several proofs, including the bijectio...")
13:06, 12 April 2023 Etone talk contribs created page 概率论与数理统计 (Spring 2023)/Average-case analysis of QuickSort (Created page with "[http://en.wikipedia.org/wiki/Quicksort '''快速排序'''（'''Quicksort'''）]是由Tony Hoare发现的基于比较的（comparison-based）排序算法。该算法的伪代码描述如下（为方便起见，假设数组元素互不相同——更一般情况的分析易推广得到）： '''''QSort'''''(A): 输入A[1...n]是存有n个不同数字的数组 if n>1 then '''pivot''' = A[1]; 将A中<pivot的元素存于数组L，将>pivot的元素存于...")
14:25, 29 March 2023 Etone talk contribs created page 组合数学 (Fall 2023)/Pólya's theory of counting (Created page with "== Groups == A group <math>(G,\cdot)</math> is set <math>G</math> along with a binary operator <math>\cdot</math> which satisfies the following axioms: * ''closure'': <math>\forall g,h\in G, g\cdot h \in G</math>; * ''associativity'': <math>\forall f,g,h\in G, f\cdot(g\cdot h)=(f\cdot g)\cdot h</math>; * ''identity'': there exists a special element <math>e\in G</math>, called the '''identity''', such that <math>e\cdot g=g</math> for any <math>g\in G</math>; * ''inverse''...")
12:45, 16 March 2023 Etone talk contribs created page 组合数学 (Fall 2023)/Sieve methods (Created page with "== Principle of Inclusion-Exclusion == Let <math>A</math> and <math>B</math> be two finite sets. The cardinality of their union is :<math>|A\cup B|=|A|+|B|-{\color{Blue}|A\cap B|}</math>. For three sets <math>A</math>, <math>B</math>, and <math>C</math>, the cardinality of the union of these three sets is computed as :<math>|A\cup B\cup C|=|A|+|B|+|C|-{\color{Blue}|A\cap B|}-{\color{Blue}|A\cap C|}-{\color{Blue}|B\cap C|}+{\color{Red}|A\cap B\cap C|}</math>. This is illu...")
17:35, 11 March 2023 Etone talk contribs created page 概率论与数理统计 (Spring 2023)/Karger's min-cut algorithm (Created page with "= Graph Cut = Let <math>G(V, E)</math> be an undirected graph. A subset <math>C\subseteq E</math> of edges is a '''cut''' of graph <math>G</math> if <math>G</math> becomes ''disconnected'' after deleting all edges in <math>C</math>. Let <math>\{S,T\}</math> be a '''bipartition''' of <math>V</math> into nonempty subsets <math>S,T\subseteq V</math>, where <math>S\cap T=\emptyset</math> and <math>S\cup T=V</math>. A cut <math>C</math> is specified by this bipartition as...")
16:43, 11 March 2023 Etone talk contribs created page 概率论与数理统计 (Spring 2023)/Polynomial identity testing (Created page with "=Polynomial Identity Testing (PIT) = The '''Polynomial Identity Testing (PIT)''' is such a problem: given as input two polynomials, determine whether they are identical. It plays a fundamental role in ''Identity Testing'' problems. First, let's consider the univariate ("one variable") case: * '''Input:''' two polynomials <math>f, g\in\mathbb{F}[x]</math> of degree <math>d</math>. * Determine whether <math>f\equiv g</math> (<math>f</math> and <math>g</math> are identica...")
08:31, 3 March 2023 Etone talk contribs created page 组合数学 (Fall 2023)/Generating functions (Created page with "== Generating Functions == In Stanley's magnificent book ''Enumerative Combinatorics'', he comments the generating function as "the most useful but most difficult to understand method (for counting)". The solution to a counting problem is usually represented as some <math>a_n</math> depending a parameter <math>n</math>. Sometimes this <math>a_n</math> is called a ''counting function'' as it is a function of the parameter <math>n</math>. <math>a_n</math> can also be tre...")
13:22, 16 February 2023 Etone talk contribs created page 组合数学 (Fall 2023)/Basic enumeration (Created page with "== Basic Enumeration == The three basic rules for enumeration are: *'''The sum rule''': for any '''''disjoint''''' finite sets <math>S</math> and <math>T</math>, the cardinality of the union <math>|S\cup T|=|S|+|T|</math>. *'''The product rule''': for any finite sets <math>S</math> and <math>T</math>, the cardinality of the Cartesian product <math>|S\times T|=|S|\cdot|T|</math>. *'''The bijection rule''': if there exists a bijection between finite sets <math>S</math> a...")
10:26, 16 February 2023 Etone talk contribs created page File:Stanley-2e.jpg
10:26, 16 February 2023 Etone talk contribs uploaded File:Stanley-2e.jpg
07:28, 13 February 2023 Etone talk contribs created page File:Probability and Computing 2ed.jpg
07:28, 13 February 2023 Etone talk contribs uploaded File:Probability and Computing 2ed.jpg
07:18, 13 February 2023 Etone talk contribs uploaded a new version of File:Grimmett probability.jpg
07:16, 13 February 2023 Etone talk contribs created page File:Grimmett probability.jpg
07:16, 13 February 2023 Etone talk contribs uploaded File:Grimmett probability.jpg
07:14, 13 February 2023 Etone talk contribs created page File:概率导论.jpeg
07:14, 13 February 2023 Etone talk contribs uploaded File:概率导论.jpeg
07:04, 13 February 2023 Etone talk contribs created page 概率论与数理统计 (Spring 2023) (Created page with "{{Infobox |name = Infobox |bodystyle = |title = 概率论与数理统计 Probability Theory and Mathematical Statistics |titlestyle = |image = |imagestyle = |caption = |captionstyle = |headerstyle = background:#ccf; |labelstyle = background:#ddf; |datastyle = |header1 =Instructors |label1 = |data1 = |header2 = |label2 = |data2 = 尹一通 |header3 = |label3 = Email |data3 = yinyt@...")
05:23, 13 February 2023 Etone talk contribs created page File:TheBook-6ed.jpeg
05:23, 13 February 2023 Etone talk contribs uploaded File:TheBook-6ed.jpeg
05:19, 13 February 2023 Etone talk contribs created page File:Alon-Spencer-4ed.jpg
05:19, 13 February 2023 Etone talk contribs uploaded File:Alon-Spencer-4ed.jpg
05:17, 13 February 2023 Etone talk contribs created page File:Lovasz-matching-theory.jpg
05:17, 13 February 2023 Etone talk contribs uploaded File:Lovasz-matching-theory.jpg
05:17, 13 February 2023 Etone talk contribs created page 组合数学 (Spring 2023)/Course materials (Created page with "== Textbooks == {|border="2" cellspacing="4" cellpadding="3" rules="all" style="margin:1em 1em 1em 0; border:solid 1px #AAAAAA; border-collapse:collapse;empty-cells:show;" |border|100px |width="100%"| :J. H. van Lint and R. M. Wilson. ''A course in Combinatorics, 2nd Edition.'' Cambridge University Press, 2001. |- |border|100px|| :S. Jukna. ''Extremal Combinatorics: With Applications in Computer Science, 2nd Edition...")
05:07, 13 February 2023 Etone talk contribs created page 组合数学 (Spring 2023) (Created page with "{{Infobox |name = Infobox |bodystyle = |title = 组合数学 Combinatorics |titlestyle = |image = |imagestyle = |caption = |captionstyle = |headerstyle = background:#ccf; |labelstyle = background:#ddf; |datastyle = |header1 =Instructor |label1 = |data1 = |header2 = |label2 = |data2 = 尹一通 |header3 = |label3 = Email |data3 = yitong.yin@gmail.com yinyt@nju.edu.cn |header4 = |la...")
15:23, 29 November 2022 Etone talk contribs created page Assignment 4, Fall 2022 (Created page with "在第四章中，我们从准地转近似下的纬向平均风场、温度场的趋势方程出发，定义了E-P通量。但是该定义下的E-P通量并没有考虑到大气湿过程的影响。如果从第三章介绍的水汽方程出发，我们可以按照以下步骤定义出一个包含大气大尺度运动中湿过程作用的广义的E-P通量。 1）在准地转近似下，如果我们按照对热力学方程的简化方法，将比湿（specific humidity...")
05:51, 23 November 2022 Etone talk contribs created page Namelist Assignment 3 2022 (Created page with "姓名学号周榆杰 191870288 罗健峰 191830098 欧阳玥芸 191830111 代欣怡 652022280002 丁宇轩 502022280004 窦吉斌 502022280006 方旭 502022280008 付凯杰 502022280009 何世诚 502022280011 胡书挥 502022280012 李晨曦 652022280005 李惠林 502022280016 李颜昀 502022280018 李颖 502022280019 林齐颢 502022280021 刘洪江 502022280024 刘芷含 502022280026 闵隽玉 502022280028 倪乘岚 5020222...")
15:45, 19 November 2022 Etone talk contribs created page 高级算法 (Fall 2022)/Greedy and Local Search (Created page with "= Scheduling = We consider the following scheduling problem: * There are <math>n</math> '''jobs''' to be processed. * There are <math>m</math> identical parallel '''machines'''. Each machine can start processing jobs at time 0 and can process at most one job at a time. * Each job <math>j=1,2,\ldots, n</math> must be processed on one of these machines for <math>p_j</math> time units without interruption. <math>p_j</math> is called the '''processing time''' of job <math>j...")
11:17, 9 November 2022 Etone talk contribs created page Namelist Assignment 2 2022 (Created page with "姓名学号周榆杰 191870288 罗健峰 191830098 欧阳玥芸 191830111 代欣怡 652022280002 丁宇轩 502022280004 窦吉斌 502022280006 付凯杰 502022280009 何世诚 502022280011 胡书挥 502022280012 李晨曦 652022280005 李惠林 502022280016 李颜昀 502022280018 李颖 502022280019 林齐颢 502022280021 刘洪江 502022280024 刘芷含 502022280026 闵隽玉 502022280028 倪乘岚 502022280030 孙楚 502022...")
10:10, 1 November 2022 Etone talk contribs created page Assignment 3, Fall 2022 (Created page with "Held-Hou(1980) 讨论了当外部强迫的经向分布呈二次勒让德多项式，即<math>\dfrac{\Theta_E(\phi,z)}{\Theta_o}=1-\dfrac{2}{3}\Delta_H P_2(\sin \phi)+\Delta_v(\dfrac{z}{H}-\dfrac{1}{2})</math>的情况下，哈德莱环流内的风场、温度场、环流的空间范围等将怎样随纬度和外力强迫的强度而变化。如果将外力强迫的空间分布改为<math>\dfrac{\Theta_E(\phi,z)}{\Theta_o}=1-\Delta_H(\sin^3 \phi - \dfrac{1}{4})+\Delta_v...")
02:39, 27 October 2022 Etone talk contribs created page Namelist Assignment 1 2022 (Created page with "姓名学号周榆杰 191870288 罗健峰 191830098 欧阳玥芸 191830111 孙森灿 191830136 代欣怡 652022280002 丁宇轩 502022280004 窦吉斌 502022280006 付凯杰 502022280009 何世诚 502022280011 胡书挥 502022280012 李晨曦 652022280005 李惠林 502022280016 李颜昀 502022280018 李颖 502022280019 林齐颢 502022280021 刘洪江 502022280024 刘芷含 502022280026 闵隽玉 502022280028 倪乘岚 502022280030 孙楚 5020...")
09:32, 24 October 2022 Etone talk contribs created page 高级算法 (Fall 2022)/Dimension Reduction (Created page with "= Metric Embedding= A '''metric space''' is a pair <math>(X,d)</math>, where <math>X</math> is a set and <math>d</math> is a '''metric''' (or '''distance''') on <math>X</math>, i.e., a function :<math>d:X^2\to\mathbb{R}_{\ge 0}</math> such that for any <math>x,y,z\in X</math>, the following axioms hold: # (identity of indiscernibles) <math>d(x,y)=0\Leftrightarrow x=y</math> # (symmetry) <math>d(x,y)=d(y,x)</math> # (triangle inequality) <math>d(x,z)\le d(x,y)+d(y,z)</ma...")
12:53, 11 October 2022 Etone talk contribs created page 高级算法 (Fall 2022)/Conditional expectations (Created page with "= Conditional Expectations = The '''conditional expectation''' of a random variable <math>Y</math> with respect to an event <math>\mathcal{E}</math> is defined by :<math> \mathbf{E}[Y\mid \mathcal{E}]=\sum_{y}y\Pr[Y=y\mid\mathcal{E}]. </math> In particular, if the event <math>\mathcal{E}</math> is <math>X=a</math>, the conditional expectation :<math> \mathbf{E}[Y\mid X=a] </math> defines a function :<math> f(a)=\mathbf{E}[Y\mid X=a]. </math> Thus, <math>\mathbf{E}[Y\mid...")
12:53, 11 October 2022 Etone talk contribs created page 高级算法 (Fall 2022)/Concentration of measure (Created page with "=Chernoff Bound= Suppose that we have a fair coin. If we toss it once, then the outcome is completely unpredictable. But if we toss it, say for 1000 times, then the number of HEADs is very likely to be around 500. This phenomenon, as illustrated in the following figure, is called the '''concentration''' of measure. The Chernoff bound is an inequality that characterizes the concentration phenomenon for the sum of independent trials. File:Coinflip.png|border|450px|cent...")
02:51, 5 October 2022 Etone talk contribs created page Assignment 2, Fall 2022 (Created page with "请在题目一和题目二中任选一题作为本章的作业题目。另外的一题可作为选做题。 ==Question 1== 假设在大气层顶（TOA），在多年全年平均的情况下，入射的太阳辐射随纬度的分布满足 <math>\begin{align} Q&=Q_o \cdot s(x), \\ s(x)&=s_o \cdot P_o(x)+ s_2 \cdot P_2(x), \end{align}</math> 其中，<math>P_o(x)=1</math>, <math>P_2(x)=\frac{1}{2}(3x^2-1)</math>, <math>s_o=1</math>, <...")
15:49, 3 October 2022 Etone talk contribs created page 高级算法 (Fall 2022)/Basic tail inequalities (Created page with "=Markov's Inequality= One of the most natural information about a random variable is its expectation, which is the first moment of the random variable. Markov's inequality draws a tail bound for a random variable from its expectation. {{Theorem |Theorem (Markov's Inequality)| :Let <math>X</math> be a random variable assuming only nonnegative values. Then, for all <math>t>0</math>, ::<math>\begin{align} \Pr[X\ge t]\le \frac{\mathbf{E}[X]}{t}. \end{align}</math> }} {{Proo...")
15:48, 3 October 2022 Etone talk contribs created page 高级算法 (Fall 2022)/Hashing and Sketching (Created page with "=Distinct Elements= Consider the following problem of '''counting distinct elements''': Suppose that <math>\Omega</math> is a sufficiently large universe. *'''Input:''' a sequence of (not necessarily distinct) elements <math>x_1,x_2,\ldots,x_n\in\Omega</math>; *'''Output:''' an estimation of the total number of distinct elements <math>z=|\{x_1,x_2,\ldots,x_n\}|</math>. A straightforward way of solving this problem is to maintain a dictionary data structure, which costs...")
08:08, 26 September 2022 Etone talk contribs created page Assignment 1, Fall 2022 (Created page with "==Question #1== 请使用多年（>20年）的NCEP/NCAR月平均再分析资料，画出各季节（至少画出冬夏两季）纬向平均温度场、纬向平均纬向风场的高度－纬度剖面分布，并简述其分布特征和季节变化特征。 ==Question #2== 请使用多年（>20年）的NCEP/NCAR月平均再分析资料，画出各季节（至少画出冬夏两季）温度场、纬向风场在各高度（850、500、100 hPa，对于温度场请再画...")
08:03, 26 September 2022 Etone talk contribs created page General Circulation(Fall 2022) (Created page with "{{Infobox |name = Infobox |bodystyle = |title = 大气环流 General Circulation of the Atmosphere |titlestyle = |headerstyle = background:#ccf; |labelstyle = background:#ddf; |datastyle = |header1 =Instructor |label1 = |data1 = |header2 = |label2 = |data2 = 张洋 |header3 = |label3 = Email |data3 = yangzhang@nju.edu.cn |header4 = |label4= office |data4= 仙林大气楼 B410 |header5 = Class |label5 = |data5 = |hea...")
11:48, 21 September 2022 Etone talk contribs created page 高级算法 (Fall 2022)/Limited independence (Created page with "= <math>k</math>-wise independence = Recall the definition of independence between events: {{Theorem |Definition (Independent events)| :Events <math>\mathcal{E}_1, \mathcal{E}_2, \ldots, \mathcal{E}_n</math> are '''mutually independent''' if, for any subset <math>I\subseteq\{1,2,\ldots,n\}</math>, ::<math>\begin{align} \Pr\left[\bigwedge_{i\in I}\mathcal{E}_i\right] &= \prod_{i\in I}\Pr[\mathcal{E}_i]. \end{align}</math> }} Similarly, we can define independence between...")
11:47, 21 September 2022 Etone talk contribs created page 高级算法 (Fall 2022)/Balls into bins (Created page with "=Balls into Bins= Consider throwing <math>m</math> balls into <math>n</math> bins uniformly and independently at random. This is equivalent to a random mapping <math>f:[m]\to[n]</math>. Needless to say, random mapping is an important random model and may have many applications in Computer Science, e.g. hashing. We are concerned with the following three questions regarding the balls into bins model: * birthday problem: the probability that every bin contains at most one...")
05:43, 13 September 2022 Etone talk contribs created page 高级算法 (Fall 2022)/Finite Field Basics (Created page with "=Field= Let <math>S</math> be a set, '''closed''' under binary operations <math>+</math> (addition) and <math>\cdot</math> (multiplication). It gives us the following algebraic structures if the corresponding set of axioms are satisfied. {|class="wikitable" !colspan="7"|Structures !Axioms !Operations |- |rowspan="9" style="background-color:#ffffcc;text-align:center;"|'''''field''''' |rowspan="8" style="background-color:#ffffcc;text-align:center;"|'''''commutative rin...")
05:43, 13 September 2022 Etone talk contribs created page 高级算法 (Fall 2022)/Fingerprinting (Created page with "=Polynomial Identity Testing (PIT) = The '''Polynomial Identity Testing (PIT)''' is such a problem: given as input two polynomials, determine whether they are identical. It plays a fundamental role in ''Identity Testing'' problems. First, let's consider the univariate ("one variable") case: * '''Input:''' two polynomials <math>f, g\in\mathbb{F}[x]</math> of degree <math>d</math>. * Determine whether <math>f\equiv g</math> (<math>f</math> and <math>g</math> are identica...")
07:31, 5 September 2022 Etone talk contribs created page 高级算法 (Fall 2022)/Probability Basics (Created page with "=Probability Space= The axiom foundation of probability theory is laid by [http://en.wikipedia.org/wiki/Andrey_Kolmogorov Kolmogorov], one of the greatest mathematician of the 20th century, who advanced various very different fields of mathematics. {{Theorem|Definition (Probability Space)| A '''probability space''' is a triple <math>(\Omega,\Sigma,\Pr)</math>. *<math>\Omega</math> is a set, called the '''sample space'''. *<math>\Sigma\subseteq 2^{\Omega}</math> is the...")
07:31, 5 September 2022 Etone talk contribs created page 高级算法 (Fall 2022)/Min-Cut and Max-Cut (Created page with "= Graph Cut = Let <math>G(V, E)</math> be an undirected graph. A subset <math>C\subseteq E</math> of edges is a '''cut''' of graph <math>G</math> if <math>G</math> becomes ''disconnected'' after deleting all edges in <math>C</math>. Let <math>\{S,T\}</math> be a '''bipartition''' of <math>V</math> into nonempty subsets <math>S,T\subseteq V</math>, where <math>S\cap T=\emptyset</math> and <math>S\cup T=V</math>. A cut <math>C</math> is specified by this bipartition as...")
07:29, 1 September 2022 User account Gispzjz talk contribs was created by Etone talk contribs
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