Gradient Descent - Batch Normalization in Neural Networks

Batch Normalization basically means that we normalize each activation individually. Training Deep Neural Networks is complicated by the fact that the distribution of each layer's inputs changes during training, as the parameters of the previous layers change. This slows down the training by requiring lower learning rates and careful parameter initialization, and makes it notoriously hard to train models with saturating nonlinearities. We refer to this phenomenon as internal covariate shift. Their paper is a fascinting deep dive into the math of how layers are affected by the input, and how this covariate shift can be reduced by applying batch normalizations. Using batch normalization means we can use higher learning rates (since gradients do not explode or vanish), making the network more resilient.