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Robustness to Adversarial Perturbations in Learning from Incomplete Data

arXiv.org Machine Learning

Robustness to adversarial perturbations has become an essential feature in the design of modern classifiers --in particular, of deep neural networks. This phenomenon originates from several empirical observations, such as [1] and [2], which show deep networks are vulnerable to adversarial attacks in the input space. So far, plenty of novel methodologies have been introduced to compensate for this shortcoming. Adversarial Training (AT) [3], Virtual AT [4] or Distillation [5] are just examples of some promising methods in this area. The majority of these approaches seek an effective defense against a point-wise adversary, who shifts input data-points toward adversarial directions, in a separate manner. However, as shown by [6], a distributional adversary who can shift the data distribution instead of the input data-points is provably more detrimental to learning. This suggests that one can greatly improve the robustness of a classifier by improving its defense against a distributional adversary rather than a point-wise one. This motivation has led to the development of Distributionally Robust Learning (DRL) [7], which has attracted intensive research interest over the last few years [8, 9, 10, 11]. Despite of all the advancements in supervised or unsupervised DRL, the amount of researches tackling this problem from a semi-supervised angle is slim to none [12].


Active embedding search via noisy paired comparisons

arXiv.org Machine Learning

Suppose that we wish to estimate a user's preference vector $w$ from paired comparisons of the form "does user $w$ prefer item $p$ or item $q$?," where both the user and items are embedded in a low-dimensional Euclidean space with distances that reflect user and item similarities. Such observations arise in numerous settings, including psychometrics and psychology experiments, search tasks, advertising, and recommender systems. In such tasks, queries can be extremely costly and subject to varying levels of response noise; thus, we aim to actively choose pairs that are most informative given the results of previous comparisons. We provide new theoretical insights into the benefits and challenges of greedy information maximization in this setting, and develop two novel strategies that maximize lower bounds on information gain and are simpler to analyze and compute respectively. We use simulated responses from a real-world dataset to validate our strategies through their similar performance to greedy information maximization, and their superior preference estimation over state-of-the-art selection methods as well as random queries.


NTP : A Neural Network Topology Profiler

arXiv.org Artificial Intelligence

Performance of end-to-end neural networks on a given hardware platform is a function of its compute and memory signature, which in-turn, is governed by a wide range of parameters such as topology size, primitives used, framework used, batching strategy, latency requirements, precision etc. Current benchmarking tools suffer from limitations such as a) being either too granular like DeepBench [1] (or) b) mandate a working implementation that is either framework specific or hardware-architecture specific or both (or) c) provide only high level benchmark metrics. In this paper, we present NTP (Neural Net Topology Profiler), a sophisticated benchmarking framework, to effectively identify memory and compute signature of an end-to-end topology on multiple hardware architectures, without the need for an actual implementation. NTP is tightly integrated with hardware specific benchmarking tools to enable exhaustive data collection and analysis. Using NTP, a deep learning researcher can quickly establish baselines needed to understand performance of an end-to-end neural network topology and make high level architectural decisions. Further, integration of NTP with frameworks like Tensorflow, Pytorch, Intel OpenVINO etc. allows for performance comparison along several vectors like a) Comparison of different frameworks on a given hardware b) Comparison of different hardware using a given framework c) Comparison across different heterogeneous hardware configurations for given framework etc. These capabilities empower a researcher to effortlessly make architectural decisions needed for achieving optimized performance on any hardware platform. The paper documents the architectural approach of NTP and demonstrates the capabilities of the tool by benchmarking Mozilla DeepSpeech, a popular Speech Recognition topology.


Using Deep Networks and Transfer Learning to Address Disinformation

arXiv.org Artificial Intelligence

We also demonstrate the the detection of inflammatory, inauthentic, or otherwise ability to use this architecture to transfer knowledge nefarious communication. Character-level convolutional from labeled data in one domain to related neural networks (CNNs) are particularly well-suited for (supervised and unsupervised) tasks. Characterlevel this task--as opposed to a word-level model--because they neural networks and transfer learning are allow for non-vernacular discourse, misspelling, and other particularly valuable tools in the disinformation social media features (e.g., emoticons) to be learned without space because of the messy nature of social media, the constraint of fixed vocabularies (Zhang et al., 2015). We lack of labeled data, and the multi-channel tactics implement an adaptation of a neural network architecture of influence campaigns. We demonstrate their effectiveness recently demonstrated to be effective for text classification in several tasks relevant for detecting (Zhang et al., 2015; Józefowicz et al., 2016). The method disinformation: spam emails, review bombing, is purely content-based and does not require any additional political sentiment, and conversation clustering.


Magnetoresistive RAM for error resilient XNOR-Nets

arXiv.org Machine Learning

We trained three Binarized Convolutional Neural Network architectures (LeNet-4, Network-In-Network, AlexNet) on a variety of datasets (MNIST, CIFAR-10, CIFAR-100, extended SVHN, ImageNet) using error-prone activations and tested them without errors to study the resilience of the training process. With the exception of the AlexNet when trained on the ImageNet dataset, we found that Bit Error Rates of a few percent during training do not degrade the test accuracy. Furthermore, by training the AlexNet on progressively smaller subsets of ImageNet classes, we observed increasing tolerance to activation errors. The ability to operate with high BERs is critical for reducing power consumption in existing hardware and for facilitating emerging memory technologies. We discuss how operating at moderate BER can enable Magnetoresistive RAM with higher endurance, speed and density.


Automatic Machine Learning by Pipeline Synthesis using Model-Based Reinforcement Learning and a Grammar

arXiv.org Machine Learning

Automatic machine learning is an important problem in the forefront of machine learning. The strongest AutoML systems are based on neural networks, evolutionary algorithms, and Bayesian optimization. Recently AlphaD3M reached state-of-the-art results with an order of magnitude speedup using reinforcement learning with self-play. In this work we extend AlphaD3M by using a pipeline grammar and a pre-trained model which generalizes from many different datasets and similar tasks. Our results demonstrate improved performance compared with our earlier work and existing methods on AutoML benchmark datasets for classification and regression tasks. In the spirit of reproducible research we make our data, models, and code publicly available.


Continual Reinforcement Learning in 3D Non-stationary Environments

arXiv.org Machine Learning

High-dimensional always-changing environments constitute a hard challenge for current reinforcement learning techniques. Artificial agents, nowadays, are often trained off-line in very static and controlled conditions in simulation such that training observations can be thought as sampled i.i.d. from the entire observations space. However, in real world settings, the environment is often non-stationary and subject to unpredictable, frequent changes. In this paper we propose and openly release CRLMaze, a new benchmark for learning continually through reinforcement in a complex 3D non-stationary task based on ViZDoom and subject to several environmental changes. Then, we introduce an end-to-end model-free continual reinforcement learning strategy showing competitive results with respect to four different baselines and not requiring any access to additional supervised signals, previously encountered environmental conditions or observations.


Efficient Batch Black-box Optimization with Deterministic Regret Bounds

arXiv.org Machine Learning

In this work, we investigate black-box optimization from the perspective of frequentist kernel methods. We propose a novel batch optimization algorithm to jointly maximize the acquisition function and select points from a whole batch in a holistic way. Theoretically, we derive regret bounds for both the noise-free and perturbation settings. Moreover, we analyze the property of the adversarial regret that is required by robust initialization for Bayesian Optimization (BO), and prove that the adversarial regret bounds decrease with the decrease of covering radius, which provides a criterion for generating (initialization point set) to minimize the bound. We then propose fast searching algorithms to generate a point set with a small covering radius for the robust initialization. Experimental results on both synthetic benchmark problems and real-world problems show the effectiveness of the proposed algorithms.


Sparse Gaussian Process Modulated Hawkes Process

arXiv.org Machine Learning

The Hawkes process has been widely applied to modeling self-exciting events, including neuron spikes, earthquakes and tweets. To avoid designing parametric kernel functions and to be able to quantify the prediction confidence, non-parametric Bayesian Hawkes processes have been proposed. However the inference of such models suffers from unscalability or slow convergence. In this paper, we first propose a new non-parametric Bayesian Hawkes process whose triggering kernel is modeled as a squared sparse Gaussian process. Second, we present the variational inference scheme for the model optimization, which has the advantage of linear time complexity by leveraging the stationarity of the triggering kernel. Third, we contribute a tighter lower bound than the evidence lower bound of the marginal likelihood for the model selection. Finally, we exploit synthetic data and large-scale social media data to validate the efficiency of our method and the practical utility of our approximate marginal likelihood. We show that our approach outperforms state-of-the-art non-parametric Bayesian and non-Bayesian methods.


Concentration bounds for linear Monge mapping estimation and optimal transport domain adaptation

arXiv.org Machine Learning

This article investigates the quality of the estimator of the linear Monge mapping between distributions. We provide the first concentration result on the linear mapping operator and prove a sample complexity of $n^{-1/2}$ when using empirical estimates of first and second order moments. This result is then used to derive a generalization bound for domain adaptation with optimal transport. As a consequence, this method approaches the performance of theoretical Bayes predictor under mild conditions on the covariance structure of the problem. We also discuss the computational complexity of the linear mapping estimation and show that when the source and target are stationary the mapping is a convolution that can be estimated very efficiently using fast Fourier transforms. Numerical experiments reproduce the behavior of the proven bounds on simulated and real data for mapping estimation and domain adaptation on images.