Batch normalization

rdf:langString Batch normalization

rdf:langString Batch normalization (also known as batch norm) is a method used to make training of artificial neural networks faster and more stable through normalization of the layers' inputs by re-centering and re-scaling. It was proposed by Sergey Ioffe and Christian Szegedy in 2015. While the effect of batch normalization is evident, the reasons behind its effectiveness remain under discussion. It was believed that it can mitigate the problem of internal covariate shift, where parameter initialization and changes in the distribution of the inputs of each layer affect the learning rate of the network. Recently, some scholars have argued that batch normalization does not reduce internal covariate shift, but rather smooths the objective function, which in turn improves the performance. However, at initialization, batch normalization in fact induces severe gradient explosion in deep networks, which is only alleviated by skip connections in residual networks. Others maintain that batch normalization achieves length-direction decoupling, and thereby accelerates neural networks. More recently a normalize gradient clipping technique and smart hyperparameter tuning has been introduced in Normalizer-Free Nets, so called "NF-Nets" which mitigates the need for batch normalization.