An optimizer is a selectable deep-learning training function that strongly influences whether a model trains effectively. Its choice is tuned alongside activation and loss functions, while network architecture usually follows the data and features being learned. section 5.1.2
Practical optimizer selection involves:
- Comparing training behavior across stochastic gradient descent (SGD), Adagrad, Adam, and RMSprop. section 5.1.2
- Treating optimizer and loss choices as major influences on whether a model trains at all. section 5.1.2
- Inspecting loss curves and generated output after changing an optimizer, especially in GAN training. section 9.2.2
Inducing vanishing gradients by changing the discriminator optimizer
In a GAN notebook, replace the discriminator's RMSprop setting with Adam using an extremely small argument value. The discriminator can become very effective at identifying fakes, while generator loss changes little and discriminator fake loss remains nearly fixed. These patterns indicate vanishing gradients; changing generator activations is then explored as a separate intervention. section 9.2.2

