Equation 8 · Part 15 · From BM25 to Agentic Retrieval: A History of Retrieval-Augmented Generation
Denominator: f(q_i, D) + k_1 × (1 - b + b × dfrac|D|avgdl)
What this part means
The complete quantity below the fraction bar; it must be nonzero for this division.
Its job in the formula
f(, D) + × (1 - b + b × dfrac|D|avgdl) occurs below the fraction bar. The quantity above the bar is divided by this expression; zero is excluded as a denominator.
Full expression→Denominator: f(q_i, D) + k_1 × (1 - b + b × dfrac|D|avgdl)→Article meaning
The passage around this formula
The Text REtrieval Conference, run annually by the U.S. National Institute of Standards and Technology from 1992 onward, gave information retrieval something the field had mostly lacked: a shared, blind evaluation on a common document set, repeated every year with published results. Robertson, Walker, and colleagues at City University London entered TREC-3 in 1994 with the Okapi system, reporting a term-weighting approach within a probabilistic relevance framework and applying it, among other extensions, to phrase weighting and to query expansion using terms drawn from an initial pilot search [ 2 ] . Over that and the following TREC rounds, the Okapi team’s tuning of term-frequency…
Learn the underlying idea
A fraction a/b means a divided by b. The top number is the numerator; the bottom number is the denominator, and it cannot be zero.
Open the illustrated fractions: division written vertically guide →
Sources cited in the surrounding passage
These citations provide research context; check each source for the exact claim it supports.