Machine Learning Fundamentals · free preview

What Training Optimizes, and What It Cannot

The training loss is an average over a finite sample, and its minimum sits at a different parameter value from the minimum of the expected loss, so optimization alone cannot deliver generalization.

1. Empirical risk and risk

Empirical risk and risk

2. Why stopping early is principled

Why stopping early is principled

3. Two kinds of stationary point

Two kinds of stationary point

4. Why the training loss can mislead

A model's training loss is driven to nearly zero by increasing its capacity, and its validation loss rises once the training loss is below a threshold. Which statement explains the divergence between the two losses?

5. The saddle point test

At a stationary point of a two-dimensional loss, the Hessian has eigenvalues +3+3 and −2-2. The point is a ____.

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