问题如下：
Can Bayes’ rule be helpful if A and B are independent? What if A and B are perfectly dependent so that B is a subset of A?
选项：
解释：
Bayes’ rule says that Pr(A|B) =Pr(B|A)Pr(A) /Pr(B)
If these events are independent, then Pr(B|A) = Pr(B) so that Pr(A|B) = Pr(A). B has no information about A and so updating with Bayes’ rule never changes the conditional probability.
If these events are perfectly dependent, then Pr(B|A) = 1, so that Pr(A|B) is just the ratio of the probabilities, Pr(A)/Pr(B).
Here the probability also only depends on unconditional probabilities and so never changes.
什么是完全独立
