# Clarke’s three laws 2

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For many years, Robert A. Heinlein, Isaac Asimov, and Arthur C. Clarke were known as the “Big Three” of science fiction.

During interviews, both in 1993 and 2004–2005, he stated that he did not believe in reincarnation, citing that there was no mechanism to make it possible, though he stated “I’m always paraphrasing J. B. S. Haldane: ‘The universe is not only stranger than we imagine, it’s stranger than we can imagine.‘”

— Wikipedia on Arthur C. Clarke

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2010.04.24 Saturday $ACHK$

# The Low Countries

Wikipedia on History of the Netherlands

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2010.04.23 Friday $ACHK$

# 重新裝載

Pure Maths 6

Past papers 20

… 無限個的是 S = a/(1-r) … 有限個的是 … 我不是太記得 … 好像是 S = a(1-r^n)/(1-r)。對不對？

（LWT：不記得。）

（LWT：那些 Form 5 時學過的東西，過了暑假以後，很多科也是這樣，我也好像忘記掉了。）

（LWT：就算東西仍然存在於腦海中，人有時會不記得的。）

1. 從來沒有 A（輸入過腦海中），還是

2. 有 A（輸入過腦海中），只是不記得。

（LWT：總之輸入過，就會永遠在腦海中？）

「忘記了輸入過的東西」和「腦海中從來也沒有那樣東西」，是兩回事。太部分人以為「忘記了某樣東西」，等如「那樣東西從腦海中消失了」。那是錯的。明不明白？

（LWT：明白。）

（LWT：那我需不需要刻意去溫習 Form 5 的東西？）

（LWT：但是很多 Form 5 AMaths（Additional Mathematics 附加數學）的公式，我都用不回出來（，不能有效運用）。）

— Me@2010.04.22

[1] 這句並不是百分百準確的科學事實，但是可信可用。

# 思考過少

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A person thinking too much can reduce the intensity of his thinking.

A person thinking too little cannot know that he thinks too little.

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— Me@2010.04.09

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2010.04.22 Thursday $copyright ACHK$

# 多次元宇宙 15

（安：問題是，怎樣才為之「主要」？）

— Me@2010.04.21

# 多次元宇宙 14

（安：因為我們其實不是太清楚「時間」是什麼，所以我們也不是太清楚「因果」是什麼 … ）

（安：等一等。如果用你這些定義，那會很奇怪。如果「眾多先決條件之一」就為之「原因」的話，就會有很多奇怪的結論。例如：如果我沒有「出世」，我就不會「讀大學」。所以「出世」是「讀大學」的「眾多先決條件之一」。換言之，我「讀大學」的「原因」是我「出了世」。但是，這並不符合我們日常生活中，「原因」這個詞的用法。）

（安：加了「之一」，就好像沒有那麼奇怪。但是，那仍然不符合我們日常生活中，「原因」這個詞的用法。如果有人問我：「為什麼你可以讀到大學？」我總不能回答：「我讀到大學的原因之一是我『出了世』。」）

「原因」這個詞，有三個可能的意思。

1. 第一個意思是「充份條件」（sufficient condition）。「所有先決條件」（all the necessary conditions）加在一起，就是「充份條件」。為免節外生枝，這裡暫時不討論這個意思。

2. 我們現在討論的「原因」是取其廣義，意思是「眾多先決條件之一」。

3. 而日常生活中的所講的「原因」，是取其狹義，意思是 「眾多先決條件中，最重要的一個」，即是「主要先決條件」。

（安：問題是，怎樣才為之「主要」？）

— Me@2010.04.20

# Inception

Christopher Nolan 3

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Nolan worked on the script for nine to ten years. When he first started thinking about making the film, the director was influenced by “that era of movies where you had The Matrix, you had Dark City, you had The Thirteenth Floor and, to a certain extent, you had Memento too. They were based in the principles that the world around you might not be real“.

— Wikipedia on Inception (film)

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2010.04.21 Wednesday $ACHK$

# Pure Maths 5

Past papers 19

… 為什麼你會時常不懂做 pure maths（純數學）的題目呢？

1. 忘記了 Factor Theorem（因子定理）；

2. 不懂用「乘法符號」來簡化運算：

— Me@2010.04.20

# Kingdom of the Netherlands

Wikipedia on Kingdom of the Netherlands

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2010.04.20 Tuesday $ACHK$

# 多次元宇宙 13

（安：我們回去有關 multi-dimensions（多次元）的問題。你將宇宙的「本體」比喻成「物件本身」，萬物「現象」比喻成「投影」。

Wikipedia, public domain image

— Me@2010.04.19

— Me@2010.04.18

# Lisp | XML

Everything we’ve learned about Lisp so far can be summarized by a single statement: Lisp is executable XML with a friendlier syntax.

— Slava Akhmechet

2010.04.19 Monday ACHK

# Time Mind I

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1. 什麼是時間? What is Time? –> So I study Physics.

2. 什麼是心靈? What is Mind? –> So I study Psychology.

3. 什麼是自我? Who am I? –> So I study Philosophy.

— Me@2008.09.15, 2010.04.12

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2010.04.19 Monday $copyright ACHK$

# Pure Maths 4

Past papers 18

… 到最後你要記（刻意背誦）的東西其實很少。即是好像小學生學生字一樣。一年級時所學的生字，到二年級時已經不是「生字」，而是「熟字」。所以，對於一個二年級學生來說，他只需要背誦二年級時所學的「生字」，而不是所有在一、二年級時所學的「生字」。

（LWT：現在我基本上打開本 pure maths（純數學）書，都不懂如何做內裡的題目。）

（LWT：如果是這樣說的話，即是我以後就溫那本 tip paper？）

（LWT：如果只溫 tip paper，會不會有些運算細節被忽略了？）

「Tip paper」這個方法，我初初發明它，主要是用來記錄大部分人常犯的錯誤，或者是自己常犯的錯誤。

— Me@2010.04.18

Always make new mistakes.

— Esther Dyson

Always make new mistakes.

Always make new mistakes.

— Me@2007

# Action at a distance

Functional programming 5

The essence of functional programming is that programs are built entirely of functions with no side effects that compute their results based solely on the values of their arguments. The advantage of the functional style is that it makes programs easier to understand. Eliminating side effects eliminates almost all possibilities for action at a distance.

— Peter Seibel

2010.04.18 Sunday ACHK

# Go West

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There where the air is free
we’ll be what we want to be
Now if we make a stand
we’ll find our promised land

— Go West

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2010.04.18 Sunday $ACHK$

# Redpill

“Lisp is the red pill.”

— John Fraser, comp.lang.lisp

The first appearance of the concept of the “red pill” in the 1999 film The Matrix. A hacker named Morpheus offers a choice to the film’s protagonist, Neo, to take the blue pill, where “the story ends, you wake up in your bed and believe whatever you want to believe”, or to take the red pill, where “you stay in wonderland, and I show you how deep the rabbithole goes.”

The term redpill is a pop culture term that was popularised in science fiction culture via the 1999 film The Matrix. The movie relies on the premise that an artificial reality that is advanced enough will be indistinguishable from reality and that no test exists that can conclusively prove that reality is not a simulation. This ties in closely with the skeptical idea that the everyday world is illusory. In the movie, a Redpill is the term used to describe a human who has been freed from the Matrix, a fictional computer-generated world set in 1999. Bluepill refers to a human still connected to the Matrix.

— Wikipedia on Redpill

2010.04.17 Saturday ACHK

# Utrecht 2

This is a file from the Wikimedia Commons.

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2010.04.17 Saturday $ACHK$

# Mortals

By policy, LISP has never really catered to mere mortals. And, of course, mere mortals have never really forgiven LISP for not catering to them.

* Larry Wall, “Programming is Hard, Let’s Go Scripting…”

2010.04.16 Friday ACHK

# Utrecht (city)

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Utrecht is host to Utrecht University, the largest university of the Netherlands, as well as several other institutes for higher education. Due to its central position within the country it is an important transportation hub (rail and road) in the Netherlands. It has the second highest number of cultural events in the Netherlands, after Amsterdam.

In Utrecht 52% of the population is female, 48% is male. Utrecht has a young population, with many inhabitants in the age category from 20 and 30 years, due to the presence of a large university.

— Wikipedia on Utrecht (city)

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2010.04.16 Friday $ACHK$