朴素贝叶斯 P(x1∣x2)=Px2P(x1,x2) P(x1,x2,x3)=P(x1)P(x2,x3∣x1) 且P(x2,x3∣x1)=P(x3∣x1,x2)P(x2∣x1) P(x1,x2,x3)=P(x1)P(x2∣x1)P(x3∣x1,x2) P(x1,x2,⋯,xn)=P(x1)P(x2∣x1)P(x3∣x1,x2)⋯P(xn∣x1,x2,⋯,xn−1)