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Equation 3 · Part 5 · Humanity Has Always Been a Human–Technology System

Symbol j

x˙i=xi(fi−fˉ)+∑jMjixj−∑jMijxi,\dot{x}_i = x_i(f_i-\bar f) + \sum_j M_{ji}x_j - \sum_j M_{ij}x_i,
jj

What this part means

j appears in the bound of this sum. The bound states where the repeated operation starts, ends, or which values it includes.

Its job in the formula

j appears in the bound of this sum. The bound states where the repeated operation starts, ends, or which values it includes.

The passage around this formula

A minimal cultural-selection model can represent the frequency xix_i of a variant i as x˙i=xi(fi−fˉ)+∑jMjixj−∑jMijxi\dot{x}_i = x_i(f_i-\bar f) + \sum_j M_{ji}x_j - \sum_j M_{ij}x_i. where fif_i is context-dependent cultural fitness and MijM_{ij} represents transformation or transmission from variant i to j . The equation is illustrative, not a claim that beliefs have fixed genes or that cultural change is reducible to one replicator law. Unlike alleles, cultural variants can be intentionally modified, horizontally transmitted, blended, externally stored, and adopted because of prestige, conformity, coercion, or institutional mandate.

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Learn the underlying idea

A variable is a named place for a value. Its letter is a local label: x can mean position in one formula and a data point in another.

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Sources cited in the article section

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