Equation 9 · Part 1 · From BM25 to Agentic Retrieval: A History of Retrieval-Augmented Generation
Symbol f
What this part means
the frequency of query term in D , |D| is the document’s length, is the average document length in the collection, and .
Its job in the formula
f is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
Full expression→Symbol f→Article meaning
Where the article explains it
where f(, D) is the frequency of query term in D , |D| is the document’s length, is the average document length in the collection, and and b are tuned constants controlling term-frequency saturation and length normalization respectively.
The passage around this formula
where f(, D) is the frequency of query term in D , |D| is the document’s length, is the average document length in the collection, and and b are tuned constants controlling term-frequency saturation and length normalization respectively. The saturation term is the substantive…
Learn the underlying idea
A function assigns an output to each allowed input. The expression f(x) means “apply f to x”.
Open the illustrated functions: inputs become outputs guide →
See this notation across published equations →
Sources cited in the article section
These citations provide research context; check each source for the exact claim it supports.