Easier to read with cream paper, a tint, more contrast or larger text? Choose your colours and text, once, for every page.

Free module

Retrieval systems

Learn retrieval systems hands on: hybrid search, reranking, query rewriting, chunk quality, access filters and agentic retrieval.

6 lessons385 min lessonSoftware engineering

The lessons

Each lesson is free to read in full. Create a free account to run its commands in a live lab and to sit its quizzes and tasks.

  1. 1 · Container lab

    Hybrid search with BM25 and vectors

    I can combine keyword and meaning search into one ranked list and say when each one wins.

    Read the lesson

  2. 2 · Container lab

    Reranking search results

    I can reorder a short list of results with a second pass and say whether it was worth its cost.

    Read the lesson

  3. 3 · Container lab

    Query rewriting for better search

    I can rewrite a question so it finds more, and check against known sources that the rewrite helped.

    Read the lesson

  4. 4 · Container lab

    Chunking structured documents for search

    I can split a structured document so that each piece keeps its heading, its table header and its source.

    Read the lesson

  5. 5 · Container lab

    Permissions and stale data in search

    I can keep a search inside what each person may see and make a deletion or a new version reach the index.

    Read the lesson

  6. 6 · Container lab

    Agentic retrieval and multi-step search

    I can let an agent search more than once, with a stop rule and a limit, and score its answers on known questions.

    Read the lesson

Worked in a real lab

Every lesson of this module is worked in a lab started for you alone. The labs it uses:

Teaching a class? Set this module for your students with a teacher guide, marked assignments and a lab for every student.