# 概率符号说明

## 概率符号说明

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* \[u(x;a,b)中的分号";"]\(#u(x;a,b)中的分号";")
* \[p(Y=y|X=x)中的竖线"|"]\(#p(Y=y|X=x)中的竖线"|")

## u(x;a,b)中的分号";"

表示**函数以分后后面的内容为参数**。

我们使用函数$u(x;a,b)$表示实数区间上的均匀分布，其中a和b是区间的端点且满足b>a。符号“;”表示**“以什么为参数”**；我们把x作为函数的自变量，a和b作为定义函数的参数。即在\[a,b]内，有$u(x;a,b)=\frac{1}{b-a}$。

## p(Y=y|X=x)中的竖线"|"

表示**条件概率**。

我们将给定X=x,Y=y发生的条件概率记为P(Y=y|X=x)，这个条件概率可以通过下面的公式计算：

$$
P(Y=y|X=x)=\frac{P(Y=y,X=x)}{P(X=x)}
$$


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