Daily Archives: April 2, 2011

神奇現實世界

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靈魂軟件論 2 | 輪迴 5　

還有，之前提過，人的心靈，其實是一個軟件/程式。軟件可以複製。輪迴的時候，究竟如何複製？而又會複製成怎麼樣？有很多可能。

所以，現實世界，其實很 magical（神奇）。

— Me@2011.04.02

2011.04.02 Saturday (c) All rights reserved by ACHK

Founders at Work 5

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I think there’s a general principle at work here: the less energy people expend on performance, the more they expend on appearances to compensate. More often than not, the energy they expend on seeming impressive makes their actual performance worse.

In big companies, there’s always going to be more politics and less scope for individual decisions.

The time may soon be coming when instead of startups trying to seem more corporate, corporations will try to seem more like startups. That would be a good thing.

— Paul Graham

2011.04.02 Saturday ACHK

Peirce’s law

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Peirce’s law in logic is named after the philosopher and logician Charles Sanders Peirce. It was taken as an axiom in his first axiomatisation of propositional logic.

In propositional calculus, Peirce’s law says that ((P→Q)→P)→P. Written out, this means that P must be true if there is a proposition Q such that the truth of P follows from the truth of if P then Q. In particular, when Q is taken to be a false formula, the law says that if P must be true whenever it implies the false, then P is true. In this way Peirce’s law implies the law of excluded middle.

Peirce’s law does not hold in intuitionistic logic or intermediate logics and cannot be deduced from the deduction theorem alone.

Under the Curry-Howard isomorphism, Peirce’s law is the type of continuation operators, e.g. call/cc in Scheme.

— Wikipedia on Peirce’s law

2011.04.02 Saturday ACHK