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What you are
comes to you.
– Ralph Waldo Emerson
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2010.03.29 Monday
Author Archives: rpflee
Clebsch-Gordan coefficients software
This program is written by me to calculate the Clebsch-Gordan coefficients.
To use it, copy-and-paste the text of this file onto DrScheme and run it.
Within DrScheme, you have to select the Language “Pretty Big”.
You can contact me if you find any bugs in this program.
2010.03.28 Sunday (c) All rights reserved by ACHK
Racket
Racket is still a dialect of Lisp and a descendant of Scheme.
— Racket
2010.03.28 Sunday ACHK
Batman Begins
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Blogger Mark Fisher states that Bruce’s search for justice requires him to learn from a proper father figure, with Thomas Wayne and Ra’s al Ghul being the two counterpoints. Alfred provides a maternal figure of unconditional love, despite the overall lack of focus on a mother figure in Bruce’s life.
Impact
Shawn Adler of MTV stated after Batman Begins, a trend of darker genre films, that either retold back-stories or rebooted them altogether, began. Examples he cited were Casino Royale, as well as the in-development RoboCop, Red Sonja, and He-Man. Filmmakers, screenwriters and producers who have mentioned the film to describe their projects include: Jon Favreau and Iron Man, Edward Norton and The Incredible Hulk, McG and Terminator Salvation (which also stars Bale), Damon Lindelof and Star Trek, Robert Downey, Jr. and Sherlock Holmes, Lorenzo di Bonaventura and G.I. Joe: The Rise of Cobra, and even Hugh Jackman and X-Men Origins: Wolverine.
— Wikipedia on Batman Begins
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2010.03.28 Sunday
Copyleft 4
The Open Invention Network (OIN) is a company that acquires patents and licenses them royalty free to entities which, in turn, agree not to assert their own patents against Linux or Linux-related applications.
— Wikipedia on Open Invention Network
2010.03.27 Saturday ACHK
浮水 2
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真姐也講過，當你遇到一個難講的題目時，唯有對考官承認：「我個人的經歷尚淺，所以不能完全掌握此題目。若果真的要我講的話，我會 … 」有如遇溺時，越爭扎 只會浸得越快。唯有放鬆，等水浮起你。
– Diary, Me@2000.04.28
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2010.03.27 Saturday
OCD 3
Past papers 13
“Past papers” means “past HKCEE/HKAL examination papers”. The topic is for Hong Kong students who are facing HKCEE or HKAL. But the general principles can also be used for tackling other public examinations.
這段改篇自2010年 1 月 3 日的對話。
我當年（十九歲，高考時期）另外一個大問題是，我有情緒病。我當時沒有「情緒病」這個概念。到大約在二十三歲時，看紀錄片才知道我的所謂「弱點」原來不是我個人的性格問題，而是一種很普遍的情緒病。到了二十八歲時，我發明了一些方法，導致我可以排除了九成的情緒病。
我所講的「情緒病」大概是這個意思：例如，考試時計了一題數後，我怕自己計錯數，所以計完以後，會檢查一次。那是正常。但是，我檢查了一次後，仍然不安心，所以會再檢查。明明只需要檢查一次，我卻檢查超過一次，自然會浪費很多時間，導致拿不到最好的成績。
（KYH：我的是另外一個類似的問題。我有時寫了一東西，例如計完一題數，我覺得字體不夠好，會擦掉，重新寫一次。那算不算是情緒病？）
輕微的不算。比喻說，間中一次打噴嚏，不算是病。但是，如果一天之中多次打噴嚏的話，那就是患了傷風感冒。
你的問題算不算「情緒病」，要視乎嚴不嚴重。你的問題嚴不嚴重？
（KYH：OK 啦 …）
「OK」即是「頗為嚴重」？
（KYH：我也不知道算不算嚴重。）
「嚴重」的意思是，你的問題，除了令你心裡不舒服外，對你還有「實質影響」。你的問題對你有沒有「實質影響」？
（KYH：我考試有時明明某一題做完做對了，但是覺得寫得很混亂，所以會擦掉，重新寫一次。）
那就應該算是「情緒病」，因為你這個問題十分浪費你的考試作答時間。如果那導致你整份試卷損失幾分的話，你該科隨時會低一個 grade（成績等級）。那就是我所講的「實質影響」。
你的心理問題算是「情緒病」，因為你的心理問題對你有心理以外的「實質影響」。
我說我在二十八歲時，可以排除了九成的情緒病。我有很多方法，其中一個方法可能對你有用，可以用來解決你這個問題。
…
— Me@2010.03.26
2010.03.26 Friday (c) All rights reserved by ACHK
The Maxwell’s equations of programming
Interactive means that programming is a dialog with Lisp. You enter an expression and Lisp computes the side effects (for example output) and the value.
So your programming session is like ‘talking’ with the Lisp system. You work with it until you get the right answers.
Alan Kay (of Smalltalk fame) calls the original definition of Lisp evaluation in Lisp the Maxwell’s equations of programming.
— Rainer Joswig
2010.03.26 Friday ACHK
Be rewritten
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Another group was worried when they realized they had to rewrite their software from scratch. I told them it would be a bad sign if they didn’t. The main function of your initial version is to be rewritten.
— Paul Graham
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2010.03.26 Friday
50 50
無關重要的選擇，應該擲毫決定。
那可以節省很多時間。
— Me@around 2000
如果有兩個抉擇：甲或乙，你只能選一個。
如果你花了三日三夜也不能決定選哪一個比較好，即是甲和乙的好處多少，其實十分相近。所以你選哪一個，對你的影響也分別不大。
既然分別不大，何不擲毫決定？
— Me, based on Mr Lee@around 2007-2008
如果擲毫所做的決定，令你心裡有少許不舒服的話，那就選相反的一個。
— an updated version by Me@around 2007-2008
— Me@2010.03.25
2010.03.25 Thursday (c) All rights reserved by ACHK
Recursion 2
To iterate is human; to recurse, divine.
L. Peter Deutsch
2010.03.25 Thursday ACHK
University-academic
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The way to get an academic position is to write great books, proving your academic competence. But you may not want an university-academic life.
— Me@around 2007
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The way to get an academic position is not to get a PhD first, but to write great books, proving your academic competence. But you may not want an university-academic life.
2010.03.25 Thursday
天才省略
Past papers 12
“Past papers” means “past HKCEE/HKAL examination papers”. The topic is for Hong Kong students who are facing HKCEE or HKAL. But the general principles can also be used for tackling other public examinations.
這段改篇自2010年 1 月 3 日的對話。
我當年的主要問題是，我打算「讀完所有東西」。那不是正確的讀書心態，因為書是沒有所謂讀得「完」的。任何一個 topic（課題）都可以無限深入研究。正確的心態是，即使你打算於某一科拿到 A 級的成績，無論是各個課題之間，還是同一個課題的不同部分之間，都應該要權衡取捨。如果花太多時間於不太重要的部分，你將會不夠時間溫習重要的部分。
我當年溫習時不懂得「取捨」，任何課題、任何部分也企圖「徹底完成」，導致沒有足夠的時間集中火力進攻真正的重點，結果拿不到 A 級的成績。所以你要拿好成績的話，就要學懂「權衡取捨」。
The art of being wise is the art of knowing what to overlook. –- William James
「天才」，就是知道什麼可以省略的人。但是要「知道什麼可以省略」，本身就要有強大的背景知識，一般人也沒有。所以如果你是「一般人」，又要「知道什麼可以省略」的話，你可以用以下兩個捷徑：
一、 靠做 pastpapers（歷來試題），歸納出重點；
二、 靠高人老師的提點。
老師的主要責任是告訴學生，什麼可以省略，什麼不可以。
— Me@2010.03.24
2010.03.24 Wednesday (c) All rights reserved by ACHK
Matrix string theory
In physics, matrix string theory is the first known set of equations that describe superstring theory in a non-perturbatively complete and consistent framework. Type IIA string theory can be shown equivalent to a maximally supersymmetric two-dimensional gauge theory, the gauge group of which is U(N) for a large value of N.
— Wikipedia on Matrix string theory
2010.03.24 Wednesday ACHK
Grigori Perelman
Known for
Riemannian geometry and geometric topology
Notable awards
Fields Medal (2006), declined
Millennium Prize (2010), declined
Sir John Ball, president of the International Mathematical Union, approached Perelman in Saint Petersburg in June 2006 to persuade him to accept the prize. After 10 hours of persuasion over two days, he gave up. Two weeks later, Perelman summed up the conversation as: “He proposed to me three alternatives: accept and come; accept and don’t come, and we will send you the medal later; third, I don’t accept the prize. From the very beginning, I told him I have chosen the third one… [the prize] was completely irrelevant for me. Everybody understood that if the proof is correct then no other recognition is needed.”
— Wikipedia on Grigori Perelman
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2010.03.24 Wednesday
心經
多次元宇宙 6
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物自身
= 物體本身
= 本體
= 如來法身
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現象
= 我們看見事件的一些方面
=（比喻成）我們看見物體的一些方面
= 投影
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例如：一隻杯是個立體。你看到那隻杯時，其實不是那隻杯本身。你所接收到的，只是那隻杯在，你的視網膜上投影（projection）。你任何一個時間所看到的，只是那個杯的，其中一個角度（projection）。
空 = 本體
色 = 投影
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2010.02.09 2010.03.23 Tuesday (c) All rights reserved by ACHK
Linux adoption
In January 2001 Microsoft CEO Bill Gates explained the attraction of adopting Linux, in an internal memo that was released in the Comes vs Microsoft case. He said:
“ Our most potent Operating System competitor is Linux and the phenomena around Open Source and free software. The same phenomena fuels competitors to all of our products. The ease of picking up Linux to learn it or to modify some piece of it is very attractive. The academic community, start up companies, foreign governments and many other constituencies are putting their best work into Linux. ”
— Wikipedia on Linux adoption
2010.03.23 Tuesday ACHK
Live forever!
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He attributes his lifelong habit of writing every day to an incident in 1932 when a carnival entertainer, Mr. Electrico, touched him on the nose with an electrified sword, made his hair stand on end, and shouted, “Live forever!” It was from then that Bradbury wanted to live forever and decided his career as an author in order to do what he was told: live forever. It was at that age that Bradbury first started to do magic. Magic was his first great love. If he had not discovered writing, he would have become a magician.
— Wikipedia on Ray Bradbury
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2010.03.23 Tuesday
無足夠資料 4
Past papers 11
“Past papers” means “past HKCEE/HKAL examination papers”. The topic is for Hong Kong students who are facing HKCEE or HKAL. But the general principles can also be used for tackling other public examinations.
這段改篇自2010年 1 月 3 日的對話。
「你的 physics 老師根本沒有教內容。」
「起碼你知道你 physics 讀得不好，都不是你自己的問題，而是你的 physics 老師失職。」
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你要記住，如果沒有足夠資料，一個人多聰明也沒有用。
例如，即使你是烹飪天才，如果你沒有足夠的食物材料，你也沒有辦法煮到美味的菜色。
同理，即使你是 physics（物理）天才，如果你沒有足夠的 physics 資料的話，你多努力去思考 physics 問題，也沒有用。
你的 physics 老師根本沒有教內容，沒有給你足夠資料。所以，你 physics 讀得不好，不是你自己的問題，而是你的 physics 老師失職。
— Me@2010.03.22
2010.03.22 Monday (c) All rights reserved by ACHK
Homomorphism
In abstract algebra, a homomorphism is a structure-preserving map between two algebraic structures (such as groups, rings, or vector spaces). The word homomorphism comes from the Greek language: (homos) meaning “same” and (morphe) meaning “shape”.
— Wikipedia on Homomorphism
2010.03.22 Monday ACHK
Physics Town 
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