Index Ai Academy
Phase 5 · Transformers · Language modeling

A bigram model

The simplest language model, built from counts.

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Why it matters

The bigram model is the simplest language model that uses context: it predicts each character from the one before it. It's small enough to see completely (one table), and it's the bridge to neural language models: train a single neural layer on the same task and it learns the very same table. Every later model in this phase is a better way of filling in that "what comes next" table.

What you'll be able to do

  • Build a bigram language model from a table of next-character counts
  • Generate text by sampling one character at a time
  • Handle unseen pairs with smoothing, and measure the improvement over unigrams
  • Train the same model as a one-layer neural network and see it reach the same answer

Before this lesson

Next in this phase: Sampling strategies