In plain words: Instead of computing gradients to nudge a network's weights, ZORB pushes the answer's targets backward using a matrix shortcut called the pseudoinverse. On an 11-layer network it reached a similar error rate 300 times faster than Adam, with no tuning.
Abstract
Gradient descent and backpropagation have enabled neural networks to achieve remarkable results in many real-world applications. Despite ongoing success, training a neural network with gradient descent can be a slow and strenuous affair. We present a simple yet faster training algorithm called Zeroth-Order Relaxed Backpropagation (ZORB). Instead of calculating gradients, ZORB uses the pseudoinverse of targets to backpropagate information. ZORB is designed to reduce the time required to train deep neural networks without penalizing performance. To illustrate the speed up, we trained a feed-forward neural network with 11 layers on MNIST and observed that ZORB converged 300 times faster than Adam while achieving a comparable error rate, without any hyperparameter tuning. We also broaden the scope of ZORB to convolutional neural networks, and apply it to subsamples of the CIFAR-10 dataset. Experiments on standard classification and regression benchmarks demonstrate ZORB's advantage over traditional backpropagation with Gradient Descent.
Varun Ranganathan, Alex Lewandowski
arXiv:2011.08895 · cs.LG, cs.NE, stat.ML · submitted Nov 17, 2020
abstract · pdf · html · To appear in "Beyond Backpropagation - Novel Ideas for Training Neural Architectures" Workshop at NeurIPS 2020