第一次上传资料,不知怎么传,只好直接发表。
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只需要证明E(XY)=E(X)E(Y)..
因为X属于由X生成的sigma代数,故
E(XY|X)=XE(Y).
从而E(XY)=E[E(XY|X)]=E[XE(Y)]=E(X)E(Y).