和&积&贝叶斯(Sum&Product&Bayes rule)
Sum: P(x)=∫P(x,y)dy
Product: P(x,y)=P(y∣x)P(x)
Bayes: P(x∣y)=P(y)P(y∣x)P(x)
常规性质(properties)
总概率为1: ∫−∞∞P(x)=1
概率为非负: P(x)∈R and P(x)≥0
常用运算
期望(Expectation): E(∫(x))=∫P(x)f(x)dx
方差(Variance): var(f(x))=E[(f(x)−E[f(x)])2]=E[f(x)2]−E[f(x)]2
协方差(Covariance): cov[x,y]=Ex,y(xy)−E(x)E(y)