CourseRetrieval-Augmented Generation: The Complete Course · Module 13: Advanced and Emerging Topics · part 90 of 95
Part 90 · Module 13: Advanced and Emerging Topics

Lesson 1: Questions the corpus cannot answer, and what is missing

32 min read·13 Oct 2026
Module 13 · Lesson 1 · About 60 minutes · Needs: score thresholds (Module 6 Lesson 3), the cross-encoder reranker (Module 8 Lesson 1), the honest "I do not know" (Module 9 Lesson 1), hard negatives (Module 11 Lesson 3)

The situation

On 25 September 2026 an agent typed "how to descale X300" into Kwame's prototype. It returned the C70 user guide, the X300 Pro specifications and an X200 blade page. The agent gave a thumbs down and escalated. No Hollin document says how to descale the X300 Pro: the right reply is "I don't know" and a hand-over.

That is labelled question q36. Module 6 showed a score bar cannot refuse it without refusing ten answerable questions. Hannah asks the wider question: what else is missing, stale or contradictory across the corpus? Hollin and its data are simulated.

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