Backpropagation
Expectation Backpropagation: Parameter-Free Training of Multilayer Neural Networks with Continuous or Discrete Weights
Soudry, Daniel, Hubara, Itay, Meir, Ron
Multilayer Neural Networks (MNNs) are commonly trained using gradient descent-based methods, such as BackPropagation (BP). Inference in probabilistic graphical models is often done using variational Bayes methods, such as Expectation Propagation (EP). We show how an EP based approach can also be used to train deterministic MNNs. Specifically, we approximate the posterior of the weights given the data using a "mean-field" factorized distribution, in an online setting. Using online EP and the central limit theorem we find an analytical approximation to the Bayes update of this posterior, as well as the resulting Bayes estimates of the weights and outputs.
Bayesian optimization for backpropagation in Monte-Carlo tree search
The robust nature of MCTS, versus a traditional approach like depth-first search in alpha-beta pruning, has not only enabled a leapfrog in performance in computer Go, but has also led to its utilization in other games where it is difficult to evaluate states, as well as in other domains (Browne et al., 2012). However, MCTS is known to suffer from slow convergence in certain situations (Coquelin and Munos, 2007), in particular when the precise calculation of a narrow tactical sequence is critical for success. For example in boardgames, (Ramanujan et al., 2010) defines a level-k search trap for player p after a move m as a state of the game where the opponent of p has a guaranteed k -move winning strategy . More relevantly, they show through a series of experiments that MCTS performs poorly even in shallow traps, in contrast to regular minimax search; see also (Ramanujan et al., 2011; Ramanujan and Sel-man, 2011). T o better understand this phenomenon, we take a closer look at the update rule Q n Q n 1 R n 1 Q n 1 n (1) which is performed during the backpropagation phase of MCTS. Here, the current estimate of the value of a state is taken to be the simple average of all previous returns accrued upon visiting that state. Proceeding, we discuss various methods which seek to improve backpropagation by challenging the basic assumptions implied by (1): (i) Value estimation by averaging returns: Instead of updating a parent node's value with that of its MAX (MIN) child as in minimax search, backpropagation in MCTS averages all returns to obtain a good signal in noisy environments (this is 1 arXiv:2001.09325v1
Model-Based Machine Learning for Joint Digital Backpropagation and PMD Compensation
Häger, Christian, Pfister, Henry D., Bütler, Rick M., Liga, Gabriele, Alvarado, Alex
More generally, one may regard the entire communication system design as an end-to-end reconstruction task and jointly optimize transmitter and receiver NNs [1]. Both traditional [2-4] and end-to-end learning [5-7] have received considerable attention for optical fiber systems. However, the reliance on NNs as universal (but sometimes poorly understood) function approximators makes it difficult to incorporate existing domain knowledge or interpret the obtained solutions. Rather than relying on NNs, a different approach is to start from an existing model and parameterize it. For fiberoptic systems, this can be done for example by considering the split-step method (SSM) for numerically solving the nonlinear Schr odinger equation (NLSE).
What Is Backpropagation?
Deep learning systems are able to learn extremely complex patterns, and they accomplish this by adjusting their weights. How are the weights of a deep neural network adjusted exactly? They are adjusted through a process called backpropagation. Without backpropagation, deep neural networks wouldn't be able to carry out tasks like recognizing images and interpreting natural language. Understanding how backpropagation works is critical to understanding deep neural networks in general, so let's delve into backpropagation and see how the process is used to adjust a network's weights.
Does Deep Learning Still Need Backpropagation?
When training deep neural networks, the goal is to automatically discover good "internal representations." One of the most widely accepted methods for this is backpropagation, which uses a gradient descent approach to adjust the neural network's weights. Now, researchers from the Victoria University of Wellington School of Engineering and Computer Science have introduced the HSIC (Hilbert-Schemidt independence criterion) bottleneck as an alternative to backpropagation for finding good representations. The new method has several distinct advantages. Instead of solving problems by using the chain rule as traditional backpropagation does, HSIC solves problems layer-by-layer, eliminating problematic vanishing and exploding gradient issues found in backpropagation.
Mean field theory for deep dropout networks: digging up gradient backpropagation deeply
Huang, Wei, Da Xu, Richard Yi, Du, Weitao, Zeng, Yutian, Zhao, Yunce
In recent years, the mean field theory has been applied to the study of neural networks and has achieved a great deal of success. The theory has been applied to various neural network structures, including CNNs, RNNs, Residual networks, and Batch normalization. Inevitably, recent work has also covered the use of dropout. The mean field theory shows that the existence of depth scales that limit the maximum depth of signal propagation and gradient backpropagation. However, the gradient backpropagation is derived under the gradient independence assumption that weights used during feed forward are drawn independently from the ones used in backpropagation. This is not how neural networks are trained in a real setting. Instead, the same weights used in a feed-forward step needs to be carried over to its corresponding backpropagation. Using this realistic condition, we perform theoretical computation on linear dropout networks and a series of experiments on dropout networks. Our empirical results show an interesting phenomenon that the length gradients can backpropagate for a single input and a pair of inputs are governed by the same depth scale. Besides, we study the relationship between variance and mean of statistical metrics of the gradient and shown an emergence of universality. Finally, we investigate the maximum trainable length for deep dropout networks through a series of experiments using MNIST and CIFAR10 and provide a more precise empirical formula that describes the trainable length than original work.
r/MachineLearning - [R] Faster AutoAugment: Learning Augmentation Strategies using Backpropagation
Abstract: Data augmentation methods are indispensable heuristics to boost the performance of deep neural networks, especially in image recognition tasks. Recently, several studies have shown that augmentation strategies found by search algorithms outperform hand-made strategies. Such methods employ black-box search algorithms over image transformations with continuous or discrete parameters and require a long time to obtain better strategies. In this paper, we propose a differentiable policy search pipeline for data augmentation, which is much faster than previous methods. We introduce approximate gradients for several transformation operations with discrete parameters as well as the differentiable mechanism for selecting operations.
Mastering Backpropagation in Neural Network
In this article, we are going to learn one of the most important Machine Learning Algorithm which is Backpropagation in Neural Network in the simplest way ever. Let's feel in a Backpropagation way. Think of a situation where we are playing against an elite grandmaster chess player. We are badly defeated by him but the grandmaster allowed us to undo our steps and rectify the errors made during the game. After going through all the previous steps, we rectified most of our errors.
Announcement Regarding Successful Development of Gradient Descent (Backpropagation) Algorithm for Quantum Computers
Quantum computing has received significant attention as a next-generation computing technology due to its potential speed and ability to solve problems considered too difficult for classical computers, as reflected in the recent discussion on Quantum Supremacy. Grid sees quantum computing not only as a tool for solving optimization and quantum chemical computation problems, but also as a tool for AI (Machine Learning, Deep Learning, etc.) calculations, such as feature extraction. Previous works have announced the successful implementation of machine learning-related algorithms, such as principal component analysis and auto-encoders, on quantum computers. This work announces the development of a gradient descent (backpropagation) algorithm, a method commonly used in machine learning for neural network parameter optimization, for use on NISQ quantum computers. Due to the non-linear nature of quantum bits (qubits), Grid proposes that this algorithm can be used to perform the feature extraction and representation calculations that deep learning methods employ.