Equation 8 · Part 9 · What Actually Happens Between a Query and an Answer in RAG
Starting index or lower bound: r in R
What this part means
This label says where the repeated addition, multiplication, or accumulation starts. Read its value or condition together with the article’s description of the index.
Its job in the formula
r in R appears in the bound of this sum. The bound states where the repeated operation starts, ends, or which values it includes.
Full expression→Starting index or lower bound: r in R→Article meaning
The passage around this formula
Reciprocal rank fusion avoids the currency problem by discarding scores altogether and combining rank positions instead. For a document d and a set of ranked result lists R , with r(d) the rank of d in a given list and a smoothing constant k : . Cormack, Clarke, and Buettcher introduced the method and reported that it consistently outperformed both the individual ranked lists and a Condorcet-style fusion baseline, with the specific virtue that it requires no score normalisation across systems with incompatible scoring functions [ 9 ] . That virtue is also its limitation: two documents ranked first in their respective lists count identically toward the fused score…
Learn the underlying idea
Σ adds a collection of terms. Π multiplies them. The lower and upper labels tell you which terms belong to the collection.
Open the illustrated sums and products: repeat an operation over an index guide →
Sources cited in the surrounding passage
These citations provide research context; check each source for the exact claim it supports.