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Equation 30 · Part 1 · The Real Economics of Shipping a Model to a Device

Symbol U

UU
UU

What this part means

U is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

Its job in the formula

U is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

The passage around this formula

…can build with it while “using AI inference that is free of cost” [ 13 ] . Read against the equation above, that phrase is not a claim that inference has no cost — it is a claim about who pays CdevC_{\mathrm{dev}} and U . Apple absorbs the variant-matrix engineering and the update-distribution bill once, centrally, at the operating-system level, and amortizes both across every app on every device rather than letting each app vendor pay its own share of the same fixed costs redundantly. A platform holder that…

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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 surrounding passage

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