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Equation 13 · Part 3 · Ten Failure Modes That Define Production RAG

Symbol d

keff=k−d,k_{\text{eff}} = k - d,
dd

What this part means

d is one of the signed contributions combined to compute the quantity on the left.

Its job in the formula

d is one of the signed contributions combined to compute the quantity on the left.

The passage around this formula

…republished passage tends to match all of them, and a naive top- k selection can fill a majority of its slots with restatements of a single fact rather than covering the breadth of what is actually in the corpus. If d of the k retrieved slots are occupied by near-duplicates of an already-retrieved passage, the effective evidence budget is not k but keff=k−dk_{\text{eff}} = k - d. and d grows with corpus redundancy in a way that is invisible to any retrieval metric computed against a deduplicated relevance-judgement set,…

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Learn the underlying idea

A variable is a named place for a value. Its letter is a local label: x can mean position in one formula and a data point in another.

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