From: Osher Doctorow on
From Osher Doctorow

What I've been discussing in the last few subsections is Probable
Influence/Causation (PI) Cause-Intersection Optimality, which roughly
speaking optimizes the Influence of Cause A on Intersection AB of A
with a particular or general set/event (Effect) B. In Section 399
early subsections, another type of PI Optimality was discussed, PI
Game Theory Optimality, which maximizes P(A-->B) and/or P ' (A-->B),
which turns out to occur iff P(A) = P(B), and roughly speaking yields
Optimal Tracking (with applications far beyond spacecraft or missile
tracking).

PI Cause-Intersection Optimality occurs when:

1) P(AB) = 2P(A) - 1 (based on P(A-->B) = P(A))

or when:

2) P(B) = 2P(A) - 1 (based on P ' (A-->B) = P(A))

The two types of Optimality only coincide exactly using (2) if P(A) =
1, which is to say if A is the Universe, since from (2) we have P(B) =
2P(A) - 1 = P(A) iff P(A) = 1. So for most practical purposes other
than for the Universe as a whole, they do not coincide, although (1)
has not been thoroughly analyzed in comparison with PI Game Theory
Optimality.

Notice that both P(A) = P(B) and P(B) = 2P(A) - 1 are linear in P(A),
since the first says P(B) = P(A), while the second says P(B) = 2P(A) -
1. Moreover, across varying (different) A or P(A), the second type
has more rapid increase of P(B) with P(A) by ordinary
differentiation..

Osher Doctorow