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 Deep Learning


Training large-scale ANNs on simulated resistive crossbar arrays

arXiv.org Artificial Intelligence

Accelerating training of artificial neural networks (ANN) with analog resistive crossbar arrays is a promising idea. While the concept has been verified on very small ANNs and toy data sets (such as MNIST), more realistically sized ANNs and datasets have not yet been tackled. However, it is to be expected that device materials and hardware design constraints, such as noisy computations, finite number of resistive states of the device materials, saturating weight and activation ranges, and limited precision of analog-to-digital converters, will cause significant challenges to the successful training of state-of-the-art ANNs. By using analog hardware aware ANN training simulations, we here explore a number of simple algorithmic compensatory measures to cope with analog noise and limited weight and output ranges and resolutions, that dramatically improve the simulated training performances on RPU arrays on intermediately to large-scale ANNs.


One-shot Information Extraction from Document Images using Neuro-Deductive Program Synthesis

arXiv.org Artificial Intelligence

Our interest in this paper is in meeting a rapidly growing industrial With the rapid advancement of Deep Learning (DL) for computer demand for information extraction from images of documents such vision problems, many DL architectures are available today for as invoices, bills, receipts etc. In practice users are able to provide a document image understanding ([11], [18], [22], [28]). But like most very small number of example images labeled with the information DLbased techniques, training these models from scratch is resource that needs to be extracted. We adopt a novel'two-level''neurodeductive', and data intensive. This is a major stumbling block for industrial approach where (a) we use pre-trained deep neural problems for which collecting and annotating data incur significant networks to populate a relational database with facts about each costs in time and money. In this paper, we use two complementary document-image; and (b) we use a form of deductive reasoning, forms learning to address this problem: related to meta-interpretive learning of transition systems to learn extraction programs: Given task-specific transitions defined using (1) Neural-learning: Using pre-trained DL models for reading the entities and relations identified by the neural detectors and document images and converting them into a structured a small number of instances (usually 1, sometimes 2) of images form by populating a predefined database schema.


Bad Global Minima Exist and SGD Can Reach Them

arXiv.org Machine Learning

Several recent works have aimed to explain why severely overparameterized models, generalize well when trained by Stochastic Gradient Descent (SGD). The emergent consensus explanation has two parts: the first is that there are "no bad local minima", while the second is that SGD performs implicit regularization by having a bias towards low complexity models. We revisit both of these ideas in the context of image classification with common deep neural network architectures. Our first finding is that there exist bad global minima, i.e., models that fit the training set perfectly, yet have poor generalization. Our second finding is that given only unlabeled training data, we can easily construct initializations that will cause SGD to quickly converge to such bad global minima. For example, on CIFAR, CINIC10, and (Restricted) ImageNet, this can be achieved by starting SGD at a model derived by fitting random labels on the training data: while subsequent SGD training (with the correct labels) will reach zero training error, the resulting model will exhibit a test accuracy degradation of up to 40% compared to training from a random initialization. Finally, we show that regularization seems to provide SGD with an escape route: once heuristics such as data augmentation are used, starting from a complex model (adversarial initialization) has no effect on the test accuracy.


Machine Learning and Visualization in Clinical Decision Support: Current State and Future Directions

arXiv.org Machine Learning

Deep learning, an area of machine learning, is set to revolutionize patient care. But it is not yet part of standard of care, especially when it comes to individual patient care. In fact, it is unclear to what extent data-driven techniques are being used to support clinical decision making (CDS). Heretofore, there has not been a review of ways in which research in machine learning and other types of data-driven techniques can contribute effectively to clinical care and the types of support they can bring to clinicians. In this paper, we consider ways in which two data driven domains - machine learning and data visualizations - can contribute to the next generation of clinical decision support systems. We review the literature regarding the ways heuristic knowledge, machine learning, and visualization are - and can be - applied to three types of CDS. There has been substantial research into the use of predictive modeling for alerts, however current CDS systems are not utilizing these methods. Approaches that leverage interactive visualizations and machine-learning inferences to organize and review patient data are gaining popularity but are still at the prototype stage and are not yet in use. CDS systems that could benefit from prescriptive machine learning (e.g., treatment recommendations for specific patients) have not yet been developed. We discuss potential reasons for the lack of deployment of data-driven methods in CDS and directions for future research.


Improving Robustness Without Sacrificing Accuracy with Patch Gaussian Augmentation

arXiv.org Machine Learning

Deploying machine learning systems in the real world requires both high accuracy on clean data and robustness to naturally occurring corruptions. While architectural advances have led to improved accuracy, building robust models remains challenging. Prior work has argued that there is an inherent trade-off between robustness and accuracy, which is exemplified by standard data augment techniques such as Cutout, which improves clean accuracy but not robustness, and additive Gaussian noise, which improves robustness but hurts accuracy. To overcome this trade-off, we introduce Patch Gaussian, a simple augmentation scheme that adds noise to randomly selected patches in an input image. Models trained with Patch Gaussian achieve state of the art on the CIFAR-10 and ImageNetCommon Corruptions benchmarks while also improving accuracy on clean data. We find that this augmentation leads to reduced sensitivity to high frequency noise(similar to Gaussian) while retaining the ability to take advantage of relevant high frequency information in the image (similar to Cutout). Finally, we show that Patch Gaussian can be used in conjunction with other regularization methods and data augmentation policies such as AutoAugment, and improves performance on the COCO object detection benchmark.


An Introduction to Variational Autoencoders

arXiv.org Machine Learning

Variational autoencoders provide a principled framework for learning deep latent-variable models and corresponding inference models. In this work, we provide an introduction to variational autoencoders and some important extensions.


Scaling and Benchmarking Self-Supervised Visual Representation Learning

arXiv.org Artificial Intelligence

Self-supervised learning aims to learn representations from the data itself without explicit manual supervision. Existing efforts ignore a crucial aspect of self-supervised learning - the ability to scale to large amount of data because self-supervision requires no manual labels. In this work, we revisit this principle and scale two popular self-supervised approaches to 100 million images. We show that by scaling on various axes (including data size and problem 'hardness'), one can largely match or even exceed the performance of supervised pre-training on a variety of tasks such as object detection, surface normal estimation (3D) and visual navigation using reinforcement learning. Scaling these methods also provides many interesting insights into the limitations of current self-supervised techniques and evaluations. We conclude that current self-supervised methods are not 'hard' enough to take full advantage of large scale data and do not seem to learn effective high level semantic representations. We also introduce an extensive benchmark across 9 different datasets and tasks. We believe that such a benchmark along with comparable evaluation settings is necessary to make meaningful progress. Code is at: https://github.com/facebookresearch/fair_self_supervision_benchmark.


One ticket to win them all: generalizing lottery ticket initializations across datasets and optimizers

arXiv.org Machine Learning

The success of lottery ticket initializations (Frankle and Carbin, 2019) suggests that small, sparsified networks can be trained so long as the network is initialized appropriately. Unfortunately, finding these "winning ticket" initializations is computationally expensive. One potential solution is to reuse the same winning tickets across a variety of datasets and optimizers. However, the generality of winning ticket initializations remains unclear. Here, we attempt to answer this question by generating winning tickets for one training configuration (optimizer and dataset) and evaluating their performance on another configuration. Perhaps surprisingly, we found that, within the natural images domain, winning ticket initializations generalized across a variety of datasets, including Fashion MNIST, SVHN, CIFAR-10/100, ImageNet, and Places365, often achieving performance close to that of winning tickets generated on the same dataset. Moreover, winning tickets generated using larger datasets consistently transferred better than those generated using smaller datasets. We also found that winning ticket initializations generalize across optimizers with high performance. These results suggest that winning ticket initializations contain inductive biases generic to neural networks more broadly which improve training across many settings and provide hope for the development of better initialization methods.


Playing the lottery with rewards and multiple languages: lottery tickets in RL and NLP

arXiv.org Artificial Intelligence

The lottery ticket hypothesis proposes that over-parameterization of deep neural networks (DNNs) aids training by increasing the probability of a "lucky" subnetwork initialization being present rather than by helping the optimization process [8]. This phenomenon is intriguing and suggests that initialization strategies for DNNs can be improved substantially, but the lottery ticket hypothesis has only previously been tested in the context of supervised learning for natural image tasks. Here, we evaluate whether "winning ticket" initializations exist in two different domains: reinforcement learning (RL) and in natural language processing (NLP). For RL, we analyzed a number of discrete-action space tasks, including both classic control and pixel control. For NLP, we examined both recurrent LSTM models and large-scale Transformer models [30]. Consistent with work in supervised image classification, we confirm that winning ticket initializations generally outperform parameter-matched random initializations, even at extreme pruning rates. Together, these results suggest that the lottery ticket hypothesis is not restricted to supervised learning of natural images, but rather represents a broader phenomenon in DNNs.


Don't Paint It Black: White-Box Explanations for Deep Learning in Computer Security

arXiv.org Machine Learning

Deep learning is increasingly used as a basic building block of security systems. Unfortunately, deep neural networks are hard to interpret, and their decision process is opaque to the practitioner. Recent work has started to address this problem by considering black-box explanations for deep learning in computer security (CCS'18). The underlying explanation methods, however, ignore the structure of neural networks and thus omit crucial information for analyzing the decision process. In this paper, we investigate white-box explanations and systematically compare them with current black-box approaches. In an extensive evaluation with learning-based systems for malware detection and vulnerability discovery, we demonstrate that white-box explanations are more concise, sparse, complete and efficient than black-box approaches. As a consequence, we generally recommend the use of white-box explanations if access to the employed neural network is available, which usually is the case for stand-alone systems for malware detection, binary analysis, and vulnerability discovery.