Lesson 4: Semantic search: finding the right help article
43 min read·14 Oct 2026
Module 6 · Lesson 4 · About 50 minutes · Needs: basic Python; TF-IDF and BM25 (Module 4 Lesson 2) and cosine similarity help; this lesson loads its own encoder
The situation
It is Monday 12 October 2026, project week 6. A customer asks Ines whether she can spread the cost of a Volt 2. Ines knows the help centre covers it, types "pay in instalments" into the keyword search, and gets the EU delivery article first. The right one, KB18 "Paying for your order", comes 20th of 24. It says "spread the cost over 12 months" and never uses the word "instalments".
Rosa's fourth job is to suggest the right article while Ines replies. This lesson builds search by meaning, scores it against keyword search on 60 labelled queries, and finds where each one fails (simulated data).