Handling the no-answer case

The hardest behaviour to get is a clean "I don’t know". Make it an explicit, allowed output instead of the model’s last resort.

Lesson 4.221m 33sAdvanced4.4k students

Chapters

21:33
  1. 0:00Introduction: The Hallucination Problem
  2. 1:46Why Do LLMs Hallucinate?
  3. 4:19The Core Idea of RAG
  4. 7:10Smarter Chunking and Indexing
  5. 9:54Dense, Sparse & Hybrid Retrieval
  6. 12:28Reranking and Context Curation
  7. 14:56Self-Correcting & Agentic RAG
  8. 17:35Grounding, Citations & Verification
  9. 19:47Limitations, Open Challenges & Closing

What this lesson covers

  • Detect when retrieval returned nothing relevant
  • Make abstaining an explicit, acceptable outcome
  • Offer a next step instead of a dead end

This lesson sits in Grounded Generation, part of Retrieval-Augmented Generation from Scratch. It assumes what came before it and leads directly into the next lesson in the module.

In this lesson you will

  • Detect when retrieval returned nothing relevant
  • Make abstaining an explicit, acceptable outcome
  • Offer a next step instead of a dead end

Resources