# Zack_M_Davis comments on [Link] The Bayesian argument against induction. - Less Wrong Discussion

4 18 July 2011 09:52PM

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Comment author: 18 July 2011 11:59:31PM *  0 points [-]

[Correction: In the original version of this comment, I claimed that the linked post was mistaken on a point of mathematics: specifically, I said that it is not the case that P(A|B) – P(A)= P(A v B|B) – P(A v B) + P(A v ~B|B) – P(A v ~B). However, Guy Srinivasan pointed out that my supposed disproof contained a mistake. Redoing my calculations, I find that the equation in question is in fact an identity. I regret the error.]

Comment author: 19 July 2011 12:31:18AM *  0 points [-]

P(Av~B|B) does not equal P(A). P((Av~B) & B) equals P(A).

Edit: it doesn't, of course. P(Av~B|B) = P(A|B) and the other thing I said is just silly.

Comment author: 19 July 2011 12:56:47AM 1 point [-]

P(Av~B|B) does not equal P(A) [...] P(Av~B|B) = P(A|B)

Whoops! You're right. I'll edit the comment to reflect this correction.

Comment author: 19 July 2011 07:23:54AM 0 points [-]

Just for general convenience: P((A+~B)B) = P(AB).