两千多年前的战国时期,魏王的大臣庞葱对魏王说:“如果有人说外面的街市有老虎,您相信吗?”魏王说不信。“如果又有一个人说呢?”魏王说:“我将半信半疑。”“如果有第三个人说呢?”魏王说:“我会相信。” 上
Xu Cui
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LaTex support (2020)

I used to use jsMath to support latex in this website, but it no longer works (I have no idea why). The one I am using right now in this blog is MathJax LaTex WordPress plugin. A pleasant surprise is that my old equations (e.g. in Balloon model) stil
Xu Cui
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Recommend 3blue1brown

When I was in high school and saw the following equation, my mind was blown! $$1+\frac{1}{4}+\frac{1}{9}+\frac{1}{16}+…=\frac{\pi^2}{6}$$ Why is Pi here? Isn’t it supposed to show up only in circle related problem? But the left-hand has n
Xu Cui
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What is the probability that the sun will rise…

Laplace introduced the sunrise problem in 18th century. With prior knowledge that the sun has risen N days in the past consecutively (not knowing the gravity rules etc), what is your confidence that the sun will rise tomorrow? Let p be the probabilit
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