The Dot Product: How AI Measures Similarity

Two users on a music app. User A listens to jazz, blues, and soul. User B listens to jazz, blues, and R&B. How similar are they? You could eyeball it. But your recommendation system cannot eyeball anything. It needs a number. A precise, calculable number that says exactly how similar two things are. The dot product produces that number. It is the most important single operation in all of AI. Not an exaggeration. Attention mechanisms in transformers, similarity search in recommendation system