Applied AI

Course map · S2 Retrieval and RAG · Episode 7 of 16

Reranking

S2 E7 Explainer · 21 slides · 23 October 2026

  1. Slide 1 of 21, Cover.
  2. Slide 2 of 21, Why it matters.
  3. Slide 3 of 21, Recap.
  4. Slide 4 of 21, Mental model.
  5. Slide 5 of 21, Mental model.
  6. Slide 6 of 21, An honest choice.
  7. Slide 7 of 21, Live, every question.
  8. Slide 8 of 21, Worked example.
  9. Slide 9 of 21, The test.
  10. Slide 10 of 21, Before the results.
  11. Slide 11 of 21, Finding.
  12. Slide 12 of 21, Finding.
  13. Slide 13 of 21, Where it breaks.
  14. Slide 14 of 21, Finding.
  15. Slide 15 of 21, The decision.
  16. Slide 16 of 21, Where it breaks.
  17. Slide 17 of 21, For engineers.
  18. Slide 18 of 21, For leaders.
  19. Slide 19 of 21, The scoreboard.
  20. Slide 20 of 21, Decision rule.
  21. Slide 21 of 21, Series map.

Lesson notes

Search was finding answers but ranking them too low, so an LLM reranker reading the top 20 lifted search from 281 to 316 of 400, for about $0.001 a question.

Decision rule

Add a reranker when the right passage is found but ranked too low. Give it a long enough shortlist, and measure what it costs per question.

Ideas in this lesson

  • Retrieval

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