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From: Osher Doctorow on 14 Jul 2010 19:15 From Osher Doctorow The Logistic Differential Equation is: 1) dy/dt = ky(1 - y) (k constant) Separating variables yields: 2) dy/[y(1 - y)] = kdt We know that: 3) 1/[y(1 - y)] = [1/y] + 1/(1 - y)] Substituting from (3) into (2) and integrating yields: 4) ln(y) - ln(1 - y) = kt + c (c constant of integration) which is equivalent to: 5) kt = ln(y) - ln(1 - y) - c Thus, time t has been decomposed into the Probable Causation/Influence (PI) form (assuming normalization into [0, 1] and c = -1: 6) kt = 1 + y1 - x1, y1 = ln(y), x1 = ln(1 - y), -c = 1 (note that since y and 1 - y yield negative numbers for logarithms, being in (0, 1), we have to assume that the constant k knocks out negatives, or something similar). Notice that y1 (the "Effect") and x1 (the "Cause") essentially differ as P(A) and 1 - P(A) differ for P(A) proportional to ln(1 - y), 1 - P(A) proportional to ln(y) or vice versa, which up to logarithms are Repulsion vs Attraction under appropriate conditions. While y has not been specified here except that it is a variable, an obvious choice for y is R (radius, distance, scale factor in Cosmology, etc.), precisely the conditions under which Repulsion vs Attraction were developed in previous posts. Osher Doctorow
From: Osher Doctorow on 14 Jul 2010 19:22
From Osher Doctorow More precisely, y1 and x1 differ "proportionately" to y and 1 - y or vice versa, up to logarithms. There is also a "second type of time," dy/dt, which has its own derivatives with respect to y, as discussed in previous posts, but I do not consider that machinery here. Osher Doctorow |