Monthly Archives: June 2012

魚目混珠 3

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Second best 5

The enemy of the “best” is the “good.”

Decisions are easier when it’s a question of “good” or “bad.” We can easily see how some ways we could spend our time are wasteful, mind-numbing, even destructive. But for most of us, the issue is not between “good” or “bad,” but between the “good” and the “best.” So often, the enemy of the best is the good.

— First Things First

— by Stephen R. Covey

The greatest enemy of “the best” is “the second best”.

— Me@2010.11.14

2012.06.05 Tuesday ACHK

閱讀理解 1.3.1

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這段改編自 2010 年 6 月 2 日的對話。

我不是叫你完全放棄。

假設「閱讀理解」部分佔了 14 分。我不是叫你，完全放棄那 14 分。我的意思是，你要有心理準備，你大概沒有可能，完全奪取那 14 分。甚至，那 14 分中，你將會失去大部分。

在這個「回到現實」的心理基礎上，才從長計議「如何盡量遠離零分」，你的策略會符合實際一點。

如果一道題目是「有道理」的，你只要根據那個「道理」作答，完全拿到那 14 分的機會就很大。比喻說，上司叫你去香港的旺角區，買一部電腦。你只要去香港的旺角區，買一部電腦，就已經完成任務。

如果一道題目是「沒有道理」的，你就不能明顯地按「道理」作答，完全拿到那 14 分的機會就很小。但是，你是有方法減低損失的。你就先看看，題目「沒有道理」之餘，會不會是「有系統地」沒有道理，每次也以同一類方法「沒有道理」。換句話說，題目雖然要求你答一些「沒有道理」的東西，但是，你大概知道，那類題目所要求的「沒有道理」東西是那一種。你只要答那類題目，所喜歡的那一種，就可以拿到一定的分數。

比喻說，上司叫你去香港的旺角區，買一部電腦。但是，根據你以往與他的相處，他每次叫你去旺角區時，其實是都想你去銅鑼灣區。那樣，你只要去香港的銅鑼灣區，買一部電腦，就可以完成任務。

— Me@2012.06.05

2012.06.05 Tuesday (c) All rights reserved by ACHK

Bayesian spam filtering

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Bayesian spam filtering (after Rev. Thomas Bayes) is a statistical technique of e-mail filtering. It makes use of a naive Bayes classifier to identify spam e-mail.

Disadvantages

Depending on the implementation, Bayesian spam filtering may be susceptible to Bayesian poisoning, a technique used by spammers in an attempt to degrade the effectiveness of spam filters that rely on Bayesian filtering. A spammer practicing Bayesian poisoning will send out emails with large amounts of legitimate text (gathered from legitimate news or literary sources). Spammer tactics include insertion of random innocuous words that are not normally associated with spam, thereby decreasing the email’s spam score, making it more likely to slip past a Bayesian spam filter.

However with (for example) Paul Graham’s scheme only the most significant probabilities are used, so that padding the text out with non-spam-related words does not affect the detection probability significantly.

Words that normally appear in large quantities in spam may also be transformed by spammers. For example, ? Viagra ? would be replaced with ? Viaagra ? or ? V!agra ? in the spam message. The recipient of the message can still read the changed words, but each of these words is met more rarely by the bayesian filter, which hinders its learning process.

As a general rule, this spamming technique does not work very well, because the derived words end up recognized by the filter just like the normal ones.

Another technique used to try to defeat Bayesian spam filters is to replace text with pictures, either directly included or linked. The whole text of the message, or some part of it, is replaced with a picture where the same text is “drawn”. The spam filter is usually unable to analyze this picture, which would contain the sensitive words like “Viagra”.

However, since many mail clients disable the display of linked pictures for security reasons, the spammer sending links to distant pictures might reach fewer targets. Also, a picture’s size in bytes is bigger than the equivalent text’s size, so the spammer needs more bandwidth to send messages directly including pictures. Some filters are more inclined to decide that a message is spam if it has mostly graphical contents. Finally, a probably more efficient solution has been proposed by Google and is used by its Gmail email system, performing an OCR (Optical Character Recognition) to every mid to large size image, analyzing the text inside.

— Wikipedia on Bayesian spam filtering

2012.06.03 Sunday ACHK

The why of love, 2.1

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軟硬智力 7.1

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How to answer this kind of questions:

Why am I so stupid?

It is not a valid question.

It is not the case that there is a pre-existing “I”, to which we can assign some qualities such as stupidity.

Instead, I am the sum of all my qualities, including the quality of being stupid.

— Me@2011.10.18

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2012.06.03 Sunday (c) All rights reserved by ACHK

應世守略 3.2

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這段改編自 2010 年 3 月 20 日的對話。

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（安：那有什麼方法，令到自己不再害怕孤獨呢？）

根據哲學家叔本華所講，人有如「寒冬裡的刺蝟」：

一方面，牠們要走近對方，互相取暖；另一方面，走得太近，又會刺傷對方。

那是一個兩難。

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但是，「平民百姓刺蝟」以外，還有一些「至尊星級刺蝟」。牠們每隻的體內，都有一個「核子反應堆」，可以自己發熱發暖。所以，牠們中的每一隻，都無懼寒冷孤獨，毋須走近其他刺蝟。

那就化解了兩難。

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一隻「至尊星級刺蝟」，間中會走近其他刺蝟。那並不是因為「被迫」或者「需要」，而是因為牠「希望」或者「享受」。如果牠去見其他「至尊星級刺蝟」，是因為牠想和其他刺蝟，交換「暖氣善意」；如果牠去見其他「平民百姓刺蝟」，是因為牠想在其他刺蝟之中，散播「暖氣善意」。

同理，你的精神世界越豐富，你就越不「需要」去見其他人。一方面，你會「希望」（而不是「需要」）與其他人相處；另一方面，你亦會十分享受，與自己相處。

相反，你的心靈生活越沉悶，你就越需要參加群體活動，以分散自己的注意力，盡力避免與自己相處。

— Me@2012.06.03

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2012.06.03 Sunday (c) All rights reserved by ACHK

Humble Indie Bundle

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The Humble Indie Bundles or Humble Bundles are a series of game bundles that are sold and distributed online at a price determined by the purchaser. The games are multi-platform, DRM-free, and independently developed, and buyers can set the revenue split between the developers, charities and humble bundle organizers.

    2.1 Main bundles
        2.1.1 Humble Indie Bundle 1
        2.1.2 Humble Indie Bundle 2
        2.1.3 Humble Indie Bundle 3
        2.1.4 Humble Indie Bundle 4
        2.1.5 Humble Indie Bundle V
       
    2.2 Game/Developer-specific bundles
        2.2.1 Humble Frozenbyte Bundle
        2.2.2 Humble Frozen Synapse Bundle
        2.2.3 Humble Voxatron Debut
        2.2.4 Humble Introversion Bundle
        2.2.5 Humble Bundle Mojam
        2.2.6 Humble Botanicula Debut
       
    2.3 Android-based bundles
        2.3.1 Humble Bundle for Android
        2.3.2 Humble Bundle for Android 2

— Wikipedia on Humble Indie Bundle

       
     
2012.06.02 Saturday ACHK

閱讀理解 1.2

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這段改編自 2010 年 6 月 2 日的對話。

如果一份閱讀理解的答案，除了你覺得沒有道理外，你所有同學也覺得沒有道理，而你的老師又解釋不到，那些答案道理何在的話，那些答案就真的是，客觀地「沒有道理」。換句話說，錯不在你，只是那份閱讀理解本身沒有價值。既然是那樣，你就毋須去理會考究它。

（CYW：但是，有很多份閱讀理解的題目，都是給予我「穿鑿附會、沒有道理」的感覺。）

可能校內考試的題目，才會是那樣。公開試的會好一點。萬一公開試的題目，都是令你無所適從的話，你就看看「閱讀理解」部分的分數，佔了整個中文科多少個百分比。

（CYW：但是，你沒有理由，要我完全放棄「閱讀理解」。）

我不是叫你完全放棄。

假設「閱讀理解」部分佔了 14 分。我不是叫你，完全放棄那 14 分。我的意思是，你要有心理準備，你大概沒有可能，完全奪取那 14 分。甚至，那 14 分中，你將會失去大部分。

在這個「回到現實」的心理基礎，才從長計議「如何盡量遠離零分」，你的策略會符合實際一點。

— Me@2012.06.02

2012.06.02 Saturday (c) All rights reserved by ACHK

Emergent space and emergent time

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General relativity has taught us that space and time should not be thought of as a static arena for other phenomena. Instead, they are dynamical players: the curvature of space and time tells matter how it should move, and matter influences spacetime’s curvature. But the lesson of quantum gravity and string theory in particular is more far-reaching: space and time do not have to exist at the very beginning – they are kind of illusions. Moreover, there can be many different illusionary geometries that emerge if we look at the same physical system.

Quantum mechanics guarantees that the concept of a completely smooth geometry is incompatible with quantum mechanics that make things fluctuate. But string theory goes much further. Geometric descriptions, such as general relativity, are only approximations valid at very long distances. At very short distances, comparable to the “length of the string” (string scale) or “the smallest meaningful black hole” (the Planck scale), physics does not admit a simple description in terms of usual geometry. Geometry is generalized to something much more grandiose, and the difference between geometry and matter disappears – this is the content of unification of gravity with other forces and matter.

— Emergent space and emergent time

— Lubos Motl

2012.06.01 Friday ACHK

應世守略 3.1

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這段改編自 2010 年 3 月 20 日的對話。

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香港是相對自由的地區。在自由的社會，沒有人可以迫你和什麼人相處。所以，至少在理論上，你不應該有「如何與很難相處的人相處」等問題。「與很難相處的人相處」的最理想（和唯一的）方法是，不要與他相處。

至於在實際上，要確切執行到這一點的話，你不可害怕孤獨。最理想是有好朋友。沒有好人和你做朋友的話，寧願沒有朋友，也不要與壞人結伴同行。

在感情上，你要做到「寧為玉碎，不作瓦存」。

— Me@2012.06.01

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2012.06.01 Friday (c) All rights reserved by ACHK