Equation 13 · Part 1 · The Hidden Infrastructure Bill Behind Every RAG Answer

Symbol E

E

E

What this part means

the number of extra context tokens each call would need to carry in place of what retrieval would otherwise have selected.

Its job in the formula

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

Full expressionSymbol EArticle meaning

Where the article explains it

Set against it, the cost of skipping retrieval and instead inlining a fixed block of extra context on every single call is $C_{\mathrm{LC}}(Q)$ = Q $\cdot$ $p_{\mathrm{in}}$ $\cdot$ E where E is the number of extra context tokens each call would need to carry in place of what retrieval would otherwise have selected, and $p_{\mathrm{in}}$ is the applicable — possibly long-context-tiered — input price.

The passage around this formula

…100,000 dollars a month — about seven times the retrieval pipeline’s bill. This is arithmetic on a stated hypothetical workload, not a measurement of either approach in production, and it depends entirely on the size of E , the amount of context a given task would actually need without retrieval; a task where the relevant evidence is small, or where the corpus fits comfortably inside the window, tilts the comparison the other way.

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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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