Expressive power describes the range and complexity of functions a model architecture can represent. In practice, model capacity is adjusted to avoid underfitting while controlling overfitting: choose a model complex enough to explain the data, but prefer simpler models when they explain it well. section 7.4 section 10.1
For a multilayer perceptron, adjust capacity by changing its architecture:
- Increase the number of layers or hidden units per layer when the model underfits or has insufficient validation accuracy. section 10.1
- When overfitting, use weight decay, early stopping, or dropout to encourage simpler models or improve generalization. section 10.1
Figure 10.1 MLP architecture
Use the MLP architecture diagram to locate the layers and hidden units that can be varied to change capacity. section 10.1









