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From: Osher Doctorow on 3 Jul 2010 03:47 From Osher Doctorow It is fairly easy to prove, as I have done earlier in this thread, that: 1) P(A-->B) + P(B-->A) = 1 + P(A<-->B) 2) P(A-->B) - P(B-->A) = P(B) - P(A) To prove (1), simply consider P{(A-->B) U (B-->A)} which is easily shown to be 1 since (A-->B) U (B-->A) = A ' U B U B ' U A. Then use P(C U D) = P(C) + P(D) - P(CD) for any (random) sets C, D. The proof of (2) is easy by direct substitution of the definitions. We can write in LISP-like notation: 3) P(A-->B) = 1 + P(AB) - P(A) = (1, B, A) 4) P(B-->A) = 1 + P(AB) - P(B) = (1, A, B) Define the Operators: 5) REVERSE(P(A-->B)) = P(B-->A) 6) CORREL(P(A-->B)) = P(A<-->B) Then we can write (1) as: 7) P(A-->B) + REVERSE(P(A-->B)) = 1 + CORREL(P(A-->B)) We can write (2) as: 8) P(A-->B) - REVERSE(P(A-->B)) = P ' (A-->B) - 1 at least formally. Whether P(B) < = P(A) in (8) is required will be left for another time. Osher Doctorow
From: Osher Doctorow on 3 Jul 2010 04:01 From Osher Doctorow In LISP-like notation, we can write (1) above as: 1) P(A-->B) + P(B-->A) = (1, B, A) + (1, A, B) = 1 + CORREL(1, B, A) Similarly, for (2): 2) P(A-->B) - P(B-->A) = (1, B, A) - (1, A, B) = P ' (A-->B) - 1 at least formally. Notice that we do not add lists like (1, B, A) + (1, A, B) componentwise, and similarly we do not subtract them componentwise. Their sums and differences, however, are related to important Operators and to +/- 1. If we want to use {1, B, A} to mean P ' (A-->B) = 1 + P(B) - P(A), then in (2) P ' (A-->B) - 1 can be written {1, B, A} - 1 formally. Osher Doctorow
From: Osher Doctorow on 3 Jul 2010 08:05
Let us write: 1) [0, B, A] = CORREL(1, B, A) = P(AB) + P(A ' B ' ) 2) [1, B, A] = 1 + CORREL(1, B, A) = 1 + P(AB) + P(A ' B ' ) Then (1) of the previous post becomes: 3) P(A-->B) + P(B-->A) = (1, B, A) + (1, A, B) = [1, B, A] Next, from the paragraph below (2) of the previous post, we have: 4) {1, B, A} = P ' (A-->B) Let us write: 5) {0, B, A} = P ' (A-->B) - 1 = {1, B, A} - 1 Then (2) of the previous post becomes: 6) P(A-->B) - P(B-->A) = (1, B, A) - (1, A, B) = {0, B, A} Notice in (6) that the subtraction of the 1s become 0 with a change in list symbols, while in (3) the addition of 1s becomes 1 with a change in list symbols. We have 3 list symbols now, representing P(A-->B), P ' (A-->B), and P(A<-->B), the 3 types of Probable Causation/Influence and/or Probable Correlation, +/- 1, namely (A, B, C), {A, B, C}, and [A, B, C], which potentially can describe quark triples, the genetic code triple codons, etc. Osher Doctorow |