Weight decay is one of the standard tricks in the neural network toolbox, but the reasons for its regularization effect are poorly understood, and recent results have cast doubt on the traditional interpretation in terms of L 2 regularization. Literal weight decay has been shown to outperform L 2 regularization for optimizers for which they differ. We empirically investigate weight decay for three optimization algorithms (SGD, Adam, and K-FAC) and a variety of network architectures. We identify three distinct mechanisms by which weight decay exerts a regularization effect, depending on the particular optimization algorithm and architecture: (1) increasing the effective learning rate, (2) approximately regularizing the inputoutput Jacobian norm, and (3) reducing the effective damping coefficient for second-order optimization. Our results provide insight into how to improve the regularization of neural networks.
Recently, REF identify three distinct mechanisms by which weight decay improves generalization: increasing the effective learning rate for BN, reducing the Jacobian norm, and reducing the effective damping parameter.
Three Mechanisms of Weight Decay Regularization
ArXiv
ArXiv
Computer Science Mathematics