Equation 9 · Part 2 · From BM25 to Agentic Retrieval: A History of Retrieval-Augmented Generation

Symbol q_i

f(q_i, D)

q_i

What this part means

$q_i$ 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

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

Full expressionSymbol q_iArticle meaning

The passage around this formula

where f( $q_i$ , D) is the frequency of query term $q_i$ in D , |D| is the document’s length, $\mathrm{avgdl}$ is the average document length in the collection, and $k_1$ and b are tuned constants controlling term-frequency saturation and length normalization respectively. The saturation term is the substantive advance over a raw term-frequency-times-IDF…

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Learn the underlying idea

A subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.

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Sources cited in the article section

[2] Okapi at TREC-3 ↗

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