Reinforcement learning has accumulated layers of complexity over the years: value functions, policy gradients, replay buffers, target networks. The Cross-Entropy Method predates all of it. Rubinstein introduced it in 1997 for rare-event simulation, ...

A fraud detection model scores 99.5% accuracy. Sounds excellent until you check the predictions: it labels every single transaction as legitimate. With only 0.5% of transactions being fraudulent, a classifier that always says "no" is right 99.5% of ...