Equation 21 · Part 1 · Retrieval Is an Evidence System, Not a Memory
Symbol k
What this part means
the recall at.
Its job in the formula
k 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 k→Article meaning
Where the article explains it
The first factor is a pure retrieval quantity: recall at k , measurable against relevance judgements with no generator involved, using the established information-retrieval apparatus that BEIR standardised [ 6 ] .
The passage around this formula
The first factor is a pure retrieval quantity: recall at k , measurable against relevance judgements with no generator involved, using the established information-retrieval apparatus that BEIR standardised [ 6 ] . The second is a pure generation quantity: given that sufficient evidence was present, did the model use it faithfully? Es and colleagues built RAGAS to score exactly this separation — retrieval effectiveness, the faithfulness with which the model uses retrieved passages, and generation quality — as a reference-free evaluation that does not require ground-truth answers, enabling faster iteration [ 17 ] .
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Sources cited in the surrounding passage
- [6] BEIR: A Heterogenous Benchmark for Zero-shot Evaluation of Information Retrieval Models ↗
- [17] Ragas: Automated Evaluation of Retrieval Augmented Generation ↗
These citations provide research context; check each source for the exact claim it supports.