Information Retrieval and Search

#The Problem

The user types "what happens if someone lies to get money" and expects to find the statute that actually covers that: "Section 420 IPC." A keyword search misses it entirely (no shared vocabulary). A semantic search misses it if the embeddings were not trained on legal text. Real search has to handle both.

IR is the pipeline under every RAG system, every search bar, every docs site's fuzzy lookup. The 2026 architecture that works in production is not a single method. It is a chain of complementary methods, each catching the failures of the one before.

This lesson builds each piece and names which failures each catches.