categories
string
doi
string
id
string
year
float64
venue
string
link
string
updated
string
published
string
title
string
abstract
string
authors
list
null
null
1611.01400
null
null
http://arxiv.org/pdf/1611.01400v1
2016-11-04T14:43:44Z
2016-11-04T14:43:44Z
Learning to Rank Scientific Documents from the Crowd
Finding related published articles is an important task in any science, but with the explosion of new work in the biomedical domain it has become especially challenging. Most existing methodologies use text similarity metrics to identify whether two articles are related or not. However biomedical knowledge discovery is hypothesis-driven. The most related articles may not be ones with the highest text similarities. In this study, we first develop an innovative crowd-sourcing approach to build an expert-annotated document-ranking corpus. Using this corpus as the gold standard, we then evaluate the approaches of using text similarity to rank the relatedness of articles. Finally, we develop and evaluate a new supervised model to automatically rank related scientific articles. Our results show that authors' ranking differ significantly from rankings by text-similarity-based models. By training a learning-to-rank model on a subset of the annotated corpus, we found the best supervised learning-to-rank model (SVM-Rank) significantly surpassed state-of-the-art baseline systems.
[ "['Jesse M Lingeman' 'Hong Yu']" ]
cs.IT cs.LG math.IT
10.1162/NECO_a_01056
1611.01414
null
null
http://arxiv.org/abs/1611.01414v3
2017-11-07T17:11:42Z
2016-11-04T15:12:47Z
Information-Theoretic Bounds and Approximations in Neural Population Coding
While Shannon's mutual information has widespread applications in many disciplines, for practical applications it is often difficult to calculate its value accurately for high-dimensional variables because of the curse of dimensionality. This paper is focused on effective approximation methods for evaluating mutual information in the context of neural population coding. For large but finite neural populations, we derive several information-theoretic asymptotic bounds and approximation formulas that remain valid in high-dimensional spaces. We prove that optimizing the population density distribution based on these approximation formulas is a convex optimization problem which allows efficient numerical solutions. Numerical simulation results confirmed that our asymptotic formulas were highly accurate for approximating mutual information for large neural populations. In special cases, the approximation formulas are exactly equal to the true mutual information. We also discuss techniques of variable transformation and dimensionality reduction to facilitate computation of the approximations.
[ "Wentao Huang and Kechen Zhang", "['Wentao Huang' 'Kechen Zhang']" ]
cs.LG cs.AI
null
1611.01423
null
null
http://arxiv.org/pdf/1611.01423v2
2017-06-10T19:18:55Z
2016-11-04T15:30:43Z
Learning Continuous Semantic Representations of Symbolic Expressions
Combining abstract, symbolic reasoning with continuous neural reasoning is a grand challenge of representation learning. As a step in this direction, we propose a new architecture, called neural equivalence networks, for the problem of learning continuous semantic representations of algebraic and logical expressions. These networks are trained to represent semantic equivalence, even of expressions that are syntactically very different. The challenge is that semantic representations must be computed in a syntax-directed manner, because semantics is compositional, but at the same time, small changes in syntax can lead to very large changes in semantics, which can be difficult for continuous neural architectures. We perform an exhaustive evaluation on the task of checking equivalence on a highly diverse class of symbolic algebraic and boolean expression types, showing that our model significantly outperforms existing architectures.
[ "['Miltiadis Allamanis' 'Pankajan Chanthirasegaran' 'Pushmeet Kohli'\n 'Charles Sutton']", "Miltiadis Allamanis, Pankajan Chanthirasegaran, Pushmeet Kohli,\n Charles Sutton" ]
cs.NE cs.LG
null
1611.01427
null
null
http://arxiv.org/pdf/1611.01427v3
2017-03-30T19:51:47Z
2016-11-04T15:47:32Z
Sparsely-Connected Neural Networks: Towards Efficient VLSI Implementation of Deep Neural Networks
Recently deep neural networks have received considerable attention due to their ability to extract and represent high-level abstractions in data sets. Deep neural networks such as fully-connected and convolutional neural networks have shown excellent performance on a wide range of recognition and classification tasks. However, their hardware implementations currently suffer from large silicon area and high power consumption due to the their high degree of complexity. The power/energy consumption of neural networks is dominated by memory accesses, the majority of which occur in fully-connected networks. In fact, they contain most of the deep neural network parameters. In this paper, we propose sparsely-connected networks, by showing that the number of connections in fully-connected networks can be reduced by up to 90% while improving the accuracy performance on three popular datasets (MNIST, CIFAR10 and SVHN). We then propose an efficient hardware architecture based on linear-feedback shift registers to reduce the memory requirements of the proposed sparsely-connected networks. The proposed architecture can save up to 90% of memory compared to the conventional implementations of fully-connected neural networks. Moreover, implementation results show up to 84% reduction in the energy consumption of a single neuron of the proposed sparsely-connected networks compared to a single neuron of fully-connected neural networks.
[ "['Arash Ardakani' 'Carlo Condo' 'Warren J. Gross']", "Arash Ardakani, Carlo Condo and Warren J. Gross" ]
cs.LG
null
1611.01449
null
null
http://arxiv.org/pdf/1611.01449v2
2018-12-04T15:39:28Z
2016-11-04T16:39:20Z
Semi-supervised deep learning by metric embedding
Deep networks are successfully used as classification models yielding state-of-the-art results when trained on a large number of labeled samples. These models, however, are usually much less suited for semi-supervised problems because of their tendency to overfit easily when trained on small amounts of data. In this work we will explore a new training objective that is targeting a semi-supervised regime with only a small subset of labeled data. This criterion is based on a deep metric embedding over distance relations within the set of labeled samples, together with constraints over the embeddings of the unlabeled set. The final learned representations are discriminative in euclidean space, and hence can be used with subsequent nearest-neighbor classification using the labeled samples.
[ "Elad Hoffer, Nir Ailon", "['Elad Hoffer' 'Nir Ailon']" ]
cs.LG cs.AI stat.ML
null
1611.01455
null
null
http://arxiv.org/pdf/1611.01455v1
2016-11-04T17:08:54Z
2016-11-04T17:08:54Z
Ways of Conditioning Generative Adversarial Networks
The GANs are generative models whose random samples realistically reflect natural images. It also can generate samples with specific attributes by concatenating a condition vector into the input, yet research on this field is not well studied. We propose novel methods of conditioning generative adversarial networks (GANs) that achieve state-of-the-art results on MNIST and CIFAR-10. We mainly introduce two models: an information retrieving model that extracts conditional information from the samples, and a spatial bilinear pooling model that forms bilinear features derived from the spatial cross product of an image and a condition vector. These methods significantly enhance log-likelihood of test data under the conditional distributions compared to the methods of concatenation.
[ "['Hanock Kwak' 'Byoung-Tak Zhang']", "Hanock Kwak and Byoung-Tak Zhang" ]
cs.LG cs.SI stat.ML
null
1611.01456
null
null
http://arxiv.org/pdf/1611.01456v1
2016-11-04T17:16:17Z
2016-11-04T17:16:17Z
Learning heat diffusion graphs
Effective information analysis generally boils down to properly identifying the structure or geometry of the data, which is often represented by a graph. In some applications, this structure may be partly determined by design constraints or pre-determined sensing arrangements, like in road transportation networks for example. In general though, the data structure is not readily available and becomes pretty difficult to define. In particular, the global smoothness assumptions, that most of the existing works adopt, are often too general and unable to properly capture localized properties of data. In this paper, we go beyond this classical data model and rather propose to represent information as a sparse combination of localized functions that live on a data structure represented by a graph. Based on this model, we focus on the problem of inferring the connectivity that best explains the data samples at different vertices of a graph that is a priori unknown. We concentrate on the case where the observed data is actually the sum of heat diffusion processes, which is a quite common model for data on networks or other irregular structures. We cast a new graph learning problem and solve it with an efficient nonconvex optimization algorithm. Experiments on both synthetic and real world data finally illustrate the benefits of the proposed graph learning framework and confirm that the data structure can be efficiently learned from data observations only. We believe that our algorithm will help solving key questions in diverse application domains such as social and biological network analysis where it is crucial to unveil proper geometry for data understanding and inference.
[ "['Dorina Thanou' 'Xiaowen Dong' 'Daniel Kressner' 'Pascal Frossard']", "Dorina Thanou, Xiaowen Dong, Daniel Kressner, and Pascal Frossard" ]
cs.LG
null
1611.01457
null
null
http://arxiv.org/pdf/1611.01457v4
2017-05-23T18:52:37Z
2016-11-04T17:20:22Z
Multi-task learning with deep model based reinforcement learning
In recent years, model-free methods that use deep learning have achieved great success in many different reinforcement learning environments. Most successful approaches focus on solving a single task, while multi-task reinforcement learning remains an open problem. In this paper, we present a model based approach to deep reinforcement learning which we use to solve different tasks simultaneously. We show that our approach not only does not degrade but actually benefits from learning multiple tasks. For our model, we also present a new kind of recurrent neural network inspired by residual networks that decouples memory from computation allowing to model complex environments that do not require lots of memory.
[ "Asier Mujika", "['Asier Mujika']" ]
cs.LG cs.CL stat.ML
null
1611.01462
null
null
http://arxiv.org/pdf/1611.01462v3
2017-03-11T19:13:52Z
2016-11-04T17:36:20Z
Tying Word Vectors and Word Classifiers: A Loss Framework for Language Modeling
Recurrent neural networks have been very successful at predicting sequences of words in tasks such as language modeling. However, all such models are based on the conventional classification framework, where the model is trained against one-hot targets, and each word is represented both as an input and as an output in isolation. This causes inefficiencies in learning both in terms of utilizing all of the information and in terms of the number of parameters needed to train. We introduce a novel theoretical framework that facilitates better learning in language modeling, and show that our framework leads to tying together the input embedding and the output projection matrices, greatly reducing the number of trainable variables. Our framework leads to state of the art performance on the Penn Treebank with a variety of network models.
[ "['Hakan Inan' 'Khashayar Khosravi' 'Richard Socher']", "Hakan Inan, Khashayar Khosravi, Richard Socher" ]
cs.LG cond-mat.dis-nn cs.AI cs.CC stat.ML
null
1611.01491
null
null
http://arxiv.org/pdf/1611.01491v6
2018-02-28T02:23:47Z
2016-11-04T18:54:50Z
Understanding Deep Neural Networks with Rectified Linear Units
In this paper we investigate the family of functions representable by deep neural networks (DNN) with rectified linear units (ReLU). We give an algorithm to train a ReLU DNN with one hidden layer to *global optimality* with runtime polynomial in the data size albeit exponential in the input dimension. Further, we improve on the known lower bounds on size (from exponential to super exponential) for approximating a ReLU deep net function by a shallower ReLU net. Our gap theorems hold for smoothly parametrized families of "hard" functions, contrary to countable, discrete families known in the literature. An example consequence of our gap theorems is the following: for every natural number $k$ there exists a function representable by a ReLU DNN with $k^2$ hidden layers and total size $k^3$, such that any ReLU DNN with at most $k$ hidden layers will require at least $\frac{1}{2}k^{k+1}-1$ total nodes. Finally, for the family of $\mathbb{R}^n\to \mathbb{R}$ DNNs with ReLU activations, we show a new lowerbound on the number of affine pieces, which is larger than previous constructions in certain regimes of the network architecture and most distinctively our lowerbound is demonstrated by an explicit construction of a *smoothly parameterized* family of functions attaining this scaling. Our construction utilizes the theory of zonotopes from polyhedral theory.
[ "Raman Arora, Amitabh Basu, Poorya Mianjy and Anirbit Mukherjee", "['Raman Arora' 'Amitabh Basu' 'Poorya Mianjy' 'Anirbit Mukherjee']" ]
cs.LG q-bio.BM
null
1611.01503
null
null
http://arxiv.org/pdf/1611.01503v1
2016-11-04T19:32:15Z
2016-11-04T19:32:15Z
Protein Secondary Structure Prediction Using Deep Multi-scale Convolutional Neural Networks and Next-Step Conditioning
Recently developed deep learning techniques have significantly improved the accuracy of various speech and image recognition systems. In this paper we adapt some of these techniques for protein secondary structure prediction. We first train a series of deep neural networks to predict eight-class secondary structure labels given a protein's amino acid sequence information and find that using recent methods for regularization, such as dropout and weight-norm constraining, leads to measurable gains in accuracy. We then adapt recent convolutional neural network architectures--Inception, ReSNet, and DenseNet with Batch Normalization--to the problem of protein structure prediction. These convolutional architectures make heavy use of multi-scale filter layers that simultaneously compute features on several scales, and use residual connections to prevent underfitting. Using a carefully modified version of these architectures, we achieve state-of-the-art performance of 70.0% per amino acid accuracy on the public CB513 benchmark dataset. Finally, we explore additions from sequence-to-sequence learning, altering the model to make its predictions conditioned on both the protein's amino acid sequence and its past secondary structure labels. We introduce a new method of ensembling such a conditional model with our convolutional model, an approach which reaches 70.6% Q8 accuracy on CB513. We argue that these results can be further refined for larger boosts in prediction accuracy through more sophisticated attempts to control overfitting of conditional models. We aim to release the code for these experiments as part of the TensorFlow repository.
[ "Akosua Busia, Jasmine Collins, Navdeep Jaitly", "['Akosua Busia' 'Jasmine Collins' 'Navdeep Jaitly']" ]
stat.ML cs.AI cs.LG
null
1611.01504
null
null
http://arxiv.org/pdf/1611.01504v1
2016-11-04T19:33:35Z
2016-11-04T19:33:35Z
Estimating Causal Direction and Confounding of Two Discrete Variables
We propose a method to classify the causal relationship between two discrete variables given only the joint distribution of the variables, acknowledging that the method is subject to an inherent baseline error. We assume that the causal system is acyclicity, but we do allow for hidden common causes. Our algorithm presupposes that the probability distributions $P(C)$ of a cause $C$ is independent from the probability distribution $P(E\mid C)$ of the cause-effect mechanism. While our classifier is trained with a Bayesian assumption of flat hyperpriors, we do not make this assumption about our test data. This work connects to recent developments on the identifiability of causal models over continuous variables under the assumption of "independent mechanisms". Carefully-commented Python notebooks that reproduce all our experiments are available online at http://vision.caltech.edu/~kchalupk/code.html.
[ "Krzysztof Chalupka, Frederick Eberhardt and Pietro Perona", "['Krzysztof Chalupka' 'Frederick Eberhardt' 'Pietro Perona']" ]
cs.LG
null
1611.01505
null
null
http://arxiv.org/pdf/1611.01505v3
2018-06-11T04:28:33Z
2016-11-04T19:42:45Z
Eve: A Gradient Based Optimization Method with Locally and Globally Adaptive Learning Rates
Adaptive gradient methods for stochastic optimization adjust the learning rate for each parameter locally. However, there is also a global learning rate which must be tuned in order to get the best performance. In this paper, we present a new algorithm that adapts the learning rate locally for each parameter separately, and also globally for all parameters together. Specifically, we modify Adam, a popular method for training deep learning models, with a coefficient that captures properties of the objective function. Empirically, we show that our method, which we call Eve, outperforms Adam and other popular methods in training deep neural networks, like convolutional neural networks for image classification, and recurrent neural networks for language tasks.
[ "Hiroaki Hayashi, Jayanth Koushik, Graham Neubig", "['Hiroaki Hayashi' 'Jayanth Koushik' 'Graham Neubig']" ]
stat.ML cs.LG
null
1611.0154
null
null
null
null
null
Topology and Geometry of Half-Rectified Network Optimization
The loss surface of deep neural networks has recently attracted interest in the optimization and machine learning communities as a prime example of high-dimensional non-convex problem. Some insights were recently gained using spin glass models and mean-field approximations, but at the expense of strongly simplifying the nonlinear nature of the model. In this work, we do not make any such assumption and study conditions on the data distribution and model architecture that prevent the existence of bad local minima. Our theoretical work quantifies and formalizes two important \emph{folklore} facts: (i) the landscape of deep linear networks has a radically different topology from that of deep half-rectified ones, and (ii) that the energy landscape in the non-linear case is fundamentally controlled by the interplay between the smoothness of the data distribution and model over-parametrization. Our main theoretical contribution is to prove that half-rectified single layer networks are asymptotically connected, and we provide explicit bounds that reveal the aforementioned interplay. The conditioning of gradient descent is the next challenge we address. We study this question through the geometry of the level sets, and we introduce an algorithm to efficiently estimate the regularity of such sets on large-scale networks. Our empirical results show that these level sets remain connected throughout all the learning phase, suggesting a near convex behavior, but they become exponentially more curvy as the energy level decays, in accordance to what is observed in practice with very low curvature attractors.
[ "C. Daniel Freeman and Joan Bruna" ]
null
null
1611.01540
null
null
http://arxiv.org/pdf/1611.01540v4
2017-06-01T19:46:41Z
2016-11-04T21:17:42Z
Topology and Geometry of Half-Rectified Network Optimization
The loss surface of deep neural networks has recently attracted interest in the optimization and machine learning communities as a prime example of high-dimensional non-convex problem. Some insights were recently gained using spin glass models and mean-field approximations, but at the expense of strongly simplifying the nonlinear nature of the model. In this work, we do not make any such assumption and study conditions on the data distribution and model architecture that prevent the existence of bad local minima. Our theoretical work quantifies and formalizes two important emph{folklore} facts: (i) the landscape of deep linear networks has a radically different topology from that of deep half-rectified ones, and (ii) that the energy landscape in the non-linear case is fundamentally controlled by the interplay between the smoothness of the data distribution and model over-parametrization. Our main theoretical contribution is to prove that half-rectified single layer networks are asymptotically connected, and we provide explicit bounds that reveal the aforementioned interplay. The conditioning of gradient descent is the next challenge we address. We study this question through the geometry of the level sets, and we introduce an algorithm to efficiently estimate the regularity of such sets on large-scale networks. Our empirical results show that these level sets remain connected throughout all the learning phase, suggesting a near convex behavior, but they become exponentially more curvy as the energy level decays, in accordance to what is observed in practice with very low curvature attractors.
[ "['C. Daniel Freeman' 'Joan Bruna']" ]
stat.ML cs.LG
null
1611.01541
null
null
http://arxiv.org/pdf/1611.01541v1
2016-11-04T21:21:53Z
2016-11-04T21:21:53Z
Classification with Ultrahigh-Dimensional Features
Although much progress has been made in classification with high-dimensional features \citep{Fan_Fan:2008, JGuo:2010, CaiSun:2014, PRXu:2014}, classification with ultrahigh-dimensional features, wherein the features much outnumber the sample size, defies most existing work. This paper introduces a novel and computationally feasible multivariate screening and classification method for ultrahigh-dimensional data. Leveraging inter-feature correlations, the proposed method enables detection of marginally weak and sparse signals and recovery of the true informative feature set, and achieves asymptotic optimal misclassification rates. We also show that the proposed procedure provides more powerful discovery boundaries compared to those in \citet{CaiSun:2014} and \citet{JJin:2009}. The performance of the proposed procedure is evaluated using simulation studies and demonstrated via classification of patients with different post-transplantation renal functional types.
[ "Yanming Li, Hyokyoung Hong, Jian Kang, Kevin He, Ji Zhu, Yi Li", "['Yanming Li' 'Hyokyoung Hong' 'Jian Kang' 'Kevin He' 'Ji Zhu' 'Yi Li']" ]
cs.CL cs.LG
null
1611.01547
null
null
http://arxiv.org/pdf/1611.01547v5
2017-04-05T15:26:51Z
2016-11-04T21:35:07Z
Automated Generation of Multilingual Clusters for the Evaluation of Distributed Representations
We propose a language-agnostic way of automatically generating sets of semantically similar clusters of entities along with sets of "outlier" elements, which may then be used to perform an intrinsic evaluation of word embeddings in the outlier detection task. We used our methodology to create a gold-standard dataset, which we call WikiSem500, and evaluated multiple state-of-the-art embeddings. The results show a correlation between performance on this dataset and performance on sentiment analysis.
[ "['Philip Blair' 'Yuval Merhav' 'Joel Barry']", "Philip Blair, Yuval Merhav, and Joel Barry" ]
cs.NE cs.AI cs.CL cs.LG
null
1611.01576
null
null
http://arxiv.org/pdf/1611.01576v2
2016-11-21T20:52:34Z
2016-11-05T00:31:25Z
Quasi-Recurrent Neural Networks
Recurrent neural networks are a powerful tool for modeling sequential data, but the dependence of each timestep's computation on the previous timestep's output limits parallelism and makes RNNs unwieldy for very long sequences. We introduce quasi-recurrent neural networks (QRNNs), an approach to neural sequence modeling that alternates convolutional layers, which apply in parallel across timesteps, and a minimalist recurrent pooling function that applies in parallel across channels. Despite lacking trainable recurrent layers, stacked QRNNs have better predictive accuracy than stacked LSTMs of the same hidden size. Due to their increased parallelism, they are up to 16 times faster at train and test time. Experiments on language modeling, sentiment classification, and character-level neural machine translation demonstrate these advantages and underline the viability of QRNNs as a basic building block for a variety of sequence tasks.
[ "['James Bradbury' 'Stephen Merity' 'Caiming Xiong' 'Richard Socher']", "James Bradbury, Stephen Merity, Caiming Xiong, Richard Socher" ]
cs.LG cs.AI cs.NE
null
1611.01578
null
null
http://arxiv.org/pdf/1611.01578v2
2017-02-15T05:28:05Z
2016-11-05T00:41:37Z
Neural Architecture Search with Reinforcement Learning
Neural networks are powerful and flexible models that work well for many difficult learning tasks in image, speech and natural language understanding. Despite their success, neural networks are still hard to design. In this paper, we use a recurrent network to generate the model descriptions of neural networks and train this RNN with reinforcement learning to maximize the expected accuracy of the generated architectures on a validation set. On the CIFAR-10 dataset, our method, starting from scratch, can design a novel network architecture that rivals the best human-invented architecture in terms of test set accuracy. Our CIFAR-10 model achieves a test error rate of 3.65, which is 0.09 percent better and 1.05x faster than the previous state-of-the-art model that used a similar architectural scheme. On the Penn Treebank dataset, our model can compose a novel recurrent cell that outperforms the widely-used LSTM cell, and other state-of-the-art baselines. Our cell achieves a test set perplexity of 62.4 on the Penn Treebank, which is 3.6 perplexity better than the previous state-of-the-art model. The cell can also be transferred to the character language modeling task on PTB and achieves a state-of-the-art perplexity of 1.214.
[ "['Barret Zoph' 'Quoc V. Le']", "Barret Zoph and Quoc V. Le" ]
cs.LG stat.ML
10.1007/s10994-016-5604-6
1611.01586
null
null
http://arxiv.org/abs/1611.01586v1
2016-11-05T01:58:12Z
2016-11-05T01:58:12Z
Class-prior Estimation for Learning from Positive and Unlabeled Data
We consider the problem of estimating the class prior in an unlabeled dataset. Under the assumption that an additional labeled dataset is available, the class prior can be estimated by fitting a mixture of class-wise data distributions to the unlabeled data distribution. However, in practice, such an additional labeled dataset is often not available. In this paper, we show that, with additional samples coming only from the positive class, the class prior of the unlabeled dataset can be estimated correctly. Our key idea is to use properly penalized divergences for model fitting to cancel the error caused by the absence of negative samples. We further show that the use of the penalized $L_1$-distance gives a computationally efficient algorithm with an analytic solution. The consistency, stability, and estimation error are theoretically analyzed. Finally, we experimentally demonstrate the usefulness of the proposed method.
[ "['Marthinus C. du Plessis' 'Gang Niu' 'Masashi Sugiyama']", "Marthinus C. du Plessis, Gang Niu, and Masashi Sugiyama" ]
cs.LG cs.CL cs.CV
null
1611.01599
null
null
http://arxiv.org/pdf/1611.01599v2
2016-12-16T16:09:34Z
2016-11-05T04:05:18Z
LipNet: End-to-End Sentence-level Lipreading
Lipreading is the task of decoding text from the movement of a speaker's mouth. Traditional approaches separated the problem into two stages: designing or learning visual features, and prediction. More recent deep lipreading approaches are end-to-end trainable (Wand et al., 2016; Chung & Zisserman, 2016a). However, existing work on models trained end-to-end perform only word classification, rather than sentence-level sequence prediction. Studies have shown that human lipreading performance increases for longer words (Easton & Basala, 1982), indicating the importance of features capturing temporal context in an ambiguous communication channel. Motivated by this observation, we present LipNet, a model that maps a variable-length sequence of video frames to text, making use of spatiotemporal convolutions, a recurrent network, and the connectionist temporal classification loss, trained entirely end-to-end. To the best of our knowledge, LipNet is the first end-to-end sentence-level lipreading model that simultaneously learns spatiotemporal visual features and a sequence model. On the GRID corpus, LipNet achieves 95.2% accuracy in sentence-level, overlapped speaker split task, outperforming experienced human lipreaders and the previous 86.4% word-level state-of-the-art accuracy (Gergen et al., 2016).
[ "['Yannis M. Assael' 'Brendan Shillingford' 'Shimon Whiteson'\n 'Nando de Freitas']", "Yannis M. Assael, Brendan Shillingford, Shimon Whiteson, Nando de\n Freitas" ]
cs.NE cs.LG
null
1611.016
null
null
null
null
null
Loss-aware Binarization of Deep Networks
Deep neural network models, though very powerful and highly successful, are computationally expensive in terms of space and time. Recently, there have been a number of attempts on binarizing the network weights and activations. This greatly reduces the network size, and replaces the underlying multiplications to additions or even XNOR bit operations. However, existing binarization schemes are based on simple matrix approximation and ignore the effect of binarization on the loss. In this paper, we propose a proximal Newton algorithm with diagonal Hessian approximation that directly minimizes the loss w.r.t. the binarized weights. The underlying proximal step has an efficient closed-form solution, and the second-order information can be efficiently obtained from the second moments already computed by the Adam optimizer. Experiments on both feedforward and recurrent networks show that the proposed loss-aware binarization algorithm outperforms existing binarization schemes, and is also more robust for wide and deep networks.
[ "Lu Hou, Quanming Yao, James T. Kwok" ]
null
null
1611.01600
null
null
http://arxiv.org/pdf/1611.01600v3
2018-05-10T11:20:09Z
2016-11-05T04:23:42Z
Loss-aware Binarization of Deep Networks
Deep neural network models, though very powerful and highly successful, are computationally expensive in terms of space and time. Recently, there have been a number of attempts on binarizing the network weights and activations. This greatly reduces the network size, and replaces the underlying multiplications to additions or even XNOR bit operations. However, existing binarization schemes are based on simple matrix approximation and ignore the effect of binarization on the loss. In this paper, we propose a proximal Newton algorithm with diagonal Hessian approximation that directly minimizes the loss w.r.t. the binarized weights. The underlying proximal step has an efficient closed-form solution, and the second-order information can be efficiently obtained from the second moments already computed by the Adam optimizer. Experiments on both feedforward and recurrent networks show that the proposed loss-aware binarization algorithm outperforms existing binarization schemes, and is also more robust for wide and deep networks.
[ "['Lu Hou' 'Quanming Yao' 'James T. Kwok']" ]
cs.LG stat.ML
null
1611.01606
null
null
http://arxiv.org/pdf/1611.01606v1
2016-11-05T05:42:40Z
2016-11-05T05:42:40Z
Learning to Play in a Day: Faster Deep Reinforcement Learning by Optimality Tightening
We propose a novel training algorithm for reinforcement learning which combines the strength of deep Q-learning with a constrained optimization approach to tighten optimality and encourage faster reward propagation. Our novel technique makes deep reinforcement learning more practical by drastically reducing the training time. We evaluate the performance of our approach on the 49 games of the challenging Arcade Learning Environment, and report significant improvements in both training time and accuracy.
[ "['Frank S. He' 'Yang Liu' 'Alexander G. Schwing' 'Jian Peng']", "Frank S. He and Yang Liu and Alexander G. Schwing and Jian Peng" ]
cs.LG cs.AI math.OC stat.ML
null
1611.01626
null
null
http://arxiv.org/pdf/1611.01626v3
2017-04-07T15:20:05Z
2016-11-05T10:49:37Z
Combining policy gradient and Q-learning
Policy gradient is an efficient technique for improving a policy in a reinforcement learning setting. However, vanilla online variants are on-policy only and not able to take advantage of off-policy data. In this paper we describe a new technique that combines policy gradient with off-policy Q-learning, drawing experience from a replay buffer. This is motivated by making a connection between the fixed points of the regularized policy gradient algorithm and the Q-values. This connection allows us to estimate the Q-values from the action preferences of the policy, to which we apply Q-learning updates. We refer to the new technique as 'PGQL', for policy gradient and Q-learning. We also establish an equivalency between action-value fitting techniques and actor-critic algorithms, showing that regularized policy gradient techniques can be interpreted as advantage function learning algorithms. We conclude with some numerical examples that demonstrate improved data efficiency and stability of PGQL. In particular, we tested PGQL on the full suite of Atari games and achieved performance exceeding that of both asynchronous advantage actor-critic (A3C) and Q-learning.
[ "Brendan O'Donoghue, Remi Munos, Koray Kavukcuoglu and Volodymyr Mnih", "[\"Brendan O'Donoghue\" 'Remi Munos' 'Koray Kavukcuoglu' 'Volodymyr Mnih']" ]
cs.LG cs.CV cs.NE q-bio.NC
null
1611.01639
null
null
http://arxiv.org/pdf/1611.01639v7
2018-01-20T13:44:32Z
2016-11-05T12:32:16Z
Robustly representing uncertainty in deep neural networks through sampling
As deep neural networks (DNNs) are applied to increasingly challenging problems, they will need to be able to represent their own uncertainty. Modeling uncertainty is one of the key features of Bayesian methods. Using Bernoulli dropout with sampling at prediction time has recently been proposed as an efficient and well performing variational inference method for DNNs. However, sampling from other multiplicative noise based variational distributions has not been investigated in depth. We evaluated Bayesian DNNs trained with Bernoulli or Gaussian multiplicative masking of either the units (dropout) or the weights (dropconnect). We tested the calibration of the probabilistic predictions of Bayesian convolutional neural networks (CNNs) on MNIST and CIFAR-10. Sampling at prediction time increased the calibration of the DNNs' probabalistic predictions. Sampling weights, whether Gaussian or Bernoulli, led to more robust representation of uncertainty compared to sampling of units. However, using either Gaussian or Bernoulli dropout led to increased test set classification accuracy. Based on these findings we used both Bernoulli dropout and Gaussian dropconnect concurrently, which we show approximates the use of a spike-and-slab variational distribution without increasing the number of learned parameters. We found that spike-and-slab sampling had higher test set performance than Gaussian dropconnect and more robustly represented its uncertainty compared to Bernoulli dropout.
[ "Patrick McClure, Nikolaus Kriegeskorte", "['Patrick McClure' 'Nikolaus Kriegeskorte']" ]
cs.DM cs.DS cs.IT cs.LG math.CO math.IT
null
1611.01655
null
null
http://arxiv.org/pdf/1611.01655v3
2017-04-25T10:44:06Z
2016-11-05T13:55:25Z
Twenty (simple) questions
A basic combinatorial interpretation of Shannon's entropy function is via the "20 questions" game. This cooperative game is played by two players, Alice and Bob: Alice picks a distribution $\pi$ over the numbers $\{1,\ldots,n\}$, and announces it to Bob. She then chooses a number $x$ according to $\pi$, and Bob attempts to identify $x$ using as few Yes/No queries as possible, on average. An optimal strategy for the "20 questions" game is given by a Huffman code for $\pi$: Bob's questions reveal the codeword for $x$ bit by bit. This strategy finds $x$ using fewer than $H(\pi)+1$ questions on average. However, the questions asked by Bob could be arbitrary. In this paper, we investigate the following question: Are there restricted sets of questions that match the performance of Huffman codes, either exactly or approximately? Our first main result shows that for every distribution $\pi$, Bob has a strategy that uses only questions of the form "$x < c$?" and "$x = c$?", and uncovers $x$ using at most $H(\pi)+1$ questions on average, matching the performance of Huffman codes in this sense. We also give a natural set of $O(rn^{1/r})$ questions that achieve a performance of at most $H(\pi)+r$, and show that $\Omega(rn^{1/r})$ questions are required to achieve such a guarantee. Our second main result gives a set $\mathcal{Q}$ of $1.25^{n+o(n)}$ questions such that for every distribution $\pi$, Bob can implement an optimal strategy for $\pi$ using only questions from $\mathcal{Q}$. We also show that $1.25^{n-o(n)}$ questions are needed, for infinitely many $n$. If we allow a small slack of $r$ over the optimal strategy, then roughly $(rn)^{\Theta(1/r)}$ questions are necessary and sufficient.
[ "['Yuval Dagan' 'Yuval Filmus' 'Ariel Gabizon' 'Shay Moran']", "Yuval Dagan, Yuval Filmus, Ariel Gabizon, Shay Moran" ]
cs.LG cs.MA cs.NE
null
1611.01673
null
null
http://arxiv.org/pdf/1611.01673v3
2017-03-02T21:20:59Z
2016-11-05T16:56:44Z
Generative Multi-Adversarial Networks
Generative adversarial networks (GANs) are a framework for producing a generative model by way of a two-player minimax game. In this paper, we propose the \emph{Generative Multi-Adversarial Network} (GMAN), a framework that extends GANs to multiple discriminators. In previous work, the successful training of GANs requires modifying the minimax objective to accelerate training early on. In contrast, GMAN can be reliably trained with the original, untampered objective. We explore a number of design perspectives with the discriminator role ranging from formidable adversary to forgiving teacher. Image generation tasks comparing the proposed framework to standard GANs demonstrate GMAN produces higher quality samples in a fraction of the iterations when measured by a pairwise GAM-type metric.
[ "Ishan Durugkar, Ian Gemp, Sridhar Mahadevan", "['Ishan Durugkar' 'Ian Gemp' 'Sridhar Mahadevan']" ]
cs.LG cs.NE
null
1611.01678
null
null
http://arxiv.org/pdf/1611.01678v1
2016-11-05T17:17:14Z
2016-11-05T17:17:14Z
Comparing learning algorithms in neural network for diagnosing cardiovascular disease
Today data mining techniques are exploited in medical science for diagnosing, overcoming and treating diseases. Neural network is one of the techniques which are widely used for diagnosis in medical field. In this article efficiency of nine algorithms, which are basis of neural network learning in diagnosing cardiovascular diseases, will be assessed. Algorithms are assessed in terms of accuracy, sensitivity, transparency, AROC and convergence rate by means of 10 fold cross validation. The results suggest that in training phase, Lonberg-M algorithm has the best efficiency in terms of all metrics, algorithm OSS has maximum accuracy in testing phase, algorithm SCG has the maximum transparency and algorithm CGB has the maximum sensitivity.
[ "['Mirmorsal Madani']", "Mirmorsal Madani" ]
cs.LG cs.DS cs.GT
null
1611.01688
null
null
http://arxiv.org/pdf/1611.01688v3
2019-08-05T14:10:08Z
2016-11-05T18:54:59Z
Oracle-Efficient Online Learning and Auction Design
We consider the design of computationally efficient online learning algorithms in an adversarial setting in which the learner has access to an offline optimization oracle. We present an algorithm called Generalized Follow-the-Perturbed-Leader and provide conditions under which it is oracle-efficient while achieving vanishing regret. Our results make significant progress on an open problem raised by Hazan and Koren, who showed that oracle-efficient algorithms do not exist in general and asked whether one can identify properties under which oracle-efficient online learning may be possible. Our auction-design framework considers an auctioneer learning an optimal auction for a sequence of adversarially selected valuations with the goal of achieving revenue that is almost as good as the optimal auction in hindsight, among a class of auctions. We give oracle-efficient learning results for: (1) VCG auctions with bidder-specific reserves in single-parameter settings, (2) envy-free item pricing in multi-item auctions, and (3) s-level auctions of Morgenstern and Roughgarden for single-item settings. The last result leads to an approximation of the overall optimal Myerson auction when bidders' valuations are drawn according to a fast-mixing Markov process, extending prior work that only gave such guarantees for the i.i.d. setting. Finally, we derive various extensions, including: (1) oracle-efficient algorithms for the contextual learning setting in which the learner has access to side information (such as bidder demographics), (2) learning with approximate oracles such as those based on Maximal-in-Range algorithms, and (3) no-regret bidding in simultaneous auctions, resolving an open problem of Daskalakis and Syrgkanis.
[ "['Miroslav Dudík' 'Nika Haghtalab' 'Haipeng Luo' 'Robert E. Schapire'\n 'Vasilis Syrgkanis' 'Jennifer Wortman Vaughan']", "Miroslav Dud\\'ik, Nika Haghtalab, Haipeng Luo, Robert E. Schapire,\n Vasilis Syrgkanis, Jennifer Wortman Vaughan" ]
cs.CL cs.AI cs.LG stat.ML
null
1611.01702
null
null
http://arxiv.org/pdf/1611.01702v2
2017-02-27T03:03:38Z
2016-11-05T21:25:07Z
TopicRNN: A Recurrent Neural Network with Long-Range Semantic Dependency
In this paper, we propose TopicRNN, a recurrent neural network (RNN)-based language model designed to directly capture the global semantic meaning relating words in a document via latent topics. Because of their sequential nature, RNNs are good at capturing the local structure of a word sequence - both semantic and syntactic - but might face difficulty remembering long-range dependencies. Intuitively, these long-range dependencies are of semantic nature. In contrast, latent topic models are able to capture the global underlying semantic structure of a document but do not account for word ordering. The proposed TopicRNN model integrates the merits of RNNs and latent topic models: it captures local (syntactic) dependencies using an RNN and global (semantic) dependencies using latent topics. Unlike previous work on contextual RNN language modeling, our model is learned end-to-end. Empirical results on word prediction show that TopicRNN outperforms existing contextual RNN baselines. In addition, TopicRNN can be used as an unsupervised feature extractor for documents. We do this for sentiment analysis on the IMDB movie review dataset and report an error rate of $6.28\%$. This is comparable to the state-of-the-art $5.91\%$ resulting from a semi-supervised approach. Finally, TopicRNN also yields sensible topics, making it a useful alternative to document models such as latent Dirichlet allocation.
[ "Adji B. Dieng, Chong Wang, Jianfeng Gao, John Paisley", "['Adji B. Dieng' 'Chong Wang' 'Jianfeng Gao' 'John Paisley']" ]
stat.ML cs.AI cs.LG
null
1611.01708
null
null
http://arxiv.org/pdf/1611.01708v2
2017-03-27T03:07:49Z
2016-11-05T23:02:25Z
Detecting Dependencies in Sparse, Multivariate Databases Using Probabilistic Programming and Non-parametric Bayes
Datasets with hundreds of variables and many missing values are commonplace. In this setting, it is both statistically and computationally challenging to detect true predictive relationships between variables and also to suppress false positives. This paper proposes an approach that combines probabilistic programming, information theory, and non-parametric Bayes. It shows how to use Bayesian non-parametric modeling to (i) build an ensemble of joint probability models for all the variables; (ii) efficiently detect marginal independencies; and (iii) estimate the conditional mutual information between arbitrary subsets of variables, subject to a broad class of constraints. Users can access these capabilities using BayesDB, a probabilistic programming platform for probabilistic data analysis, by writing queries in a simple, SQL-like language. This paper demonstrates empirically that the method can (i) detect context-specific (in)dependencies on challenging synthetic problems and (ii) yield improved sensitivity and specificity over baselines from statistics and machine learning, on a real-world database of over 300 sparsely observed indicators of macroeconomic development and public health.
[ "Feras Saad, Vikash Mansinghka", "['Feras Saad' 'Vikash Mansinghka']" ]
cs.LG cs.CL
null
1611.01714
null
null
http://arxiv.org/pdf/1611.01714v1
2016-11-06T01:32:39Z
2016-11-06T01:32:39Z
Beyond Fine Tuning: A Modular Approach to Learning on Small Data
In this paper we present a technique to train neural network models on small amounts of data. Current methods for training neural networks on small amounts of rich data typically rely on strategies such as fine-tuning a pre-trained neural network or the use of domain-specific hand-engineered features. Here we take the approach of treating network layers, or entire networks, as modules and combine pre-trained modules with untrained modules, to learn the shift in distributions between data sets. The central impact of using a modular approach comes from adding new representations to a network, as opposed to replacing representations via fine-tuning. Using this technique, we are able surpass results using standard fine-tuning transfer learning approaches, and we are also able to significantly increase performance over such approaches when using smaller amounts of data.
[ "['Ark Anderson' 'Kyle Shaffer' 'Artem Yankov' 'Court D. Corley'\n 'Nathan O. Hodas']", "Ark Anderson, Kyle Shaffer, Artem Yankov, Court D. Corley, Nathan O.\n Hodas" ]
stat.ML cs.LG
null
1611.01722
null
null
http://arxiv.org/pdf/1611.01722v2
2016-11-26T01:08:47Z
2016-11-06T02:40:41Z
Learning to Draw Samples: With Application to Amortized MLE for Generative Adversarial Learning
We propose a simple algorithm to train stochastic neural networks to draw samples from given target distributions for probabilistic inference. Our method is based on iteratively adjusting the neural network parameters so that the output changes along a Stein variational gradient that maximumly decreases the KL divergence with the target distribution. Our method works for any target distribution specified by their unnormalized density function, and can train any black-box architectures that are differentiable in terms of the parameters we want to adapt. As an application of our method, we propose an amortized MLE algorithm for training deep energy model, where a neural sampler is adaptively trained to approximate the likelihood function. Our method mimics an adversarial game between the deep energy model and the neural sampler, and obtains realistic-looking images competitive with the state-of-the-art results.
[ "['Dilin Wang' 'Qiang Liu']", "Dilin Wang, Qiang Liu" ]
cs.CL cs.LG
null
1611.01724
null
null
http://arxiv.org/pdf/1611.01724v2
2017-09-11T21:00:30Z
2016-11-06T03:17:42Z
Words or Characters? Fine-grained Gating for Reading Comprehension
Previous work combines word-level and character-level representations using concatenation or scalar weighting, which is suboptimal for high-level tasks like reading comprehension. We present a fine-grained gating mechanism to dynamically combine word-level and character-level representations based on properties of the words. We also extend the idea of fine-grained gating to modeling the interaction between questions and paragraphs for reading comprehension. Experiments show that our approach can improve the performance on reading comprehension tasks, achieving new state-of-the-art results on the Children's Book Test dataset. To demonstrate the generality of our gating mechanism, we also show improved results on a social media tag prediction task.
[ "Zhilin Yang, Bhuwan Dhingra, Ye Yuan, Junjie Hu, William W. Cohen,\n Ruslan Salakhutdinov", "['Zhilin Yang' 'Bhuwan Dhingra' 'Ye Yuan' 'Junjie Hu' 'William W. Cohen'\n 'Ruslan Salakhutdinov']" ]
cs.CR cs.LG
null
1611.01726
null
null
http://arxiv.org/pdf/1611.01726v1
2016-11-06T04:07:29Z
2016-11-06T04:07:29Z
LSTM-Based System-Call Language Modeling and Robust Ensemble Method for Designing Host-Based Intrusion Detection Systems
In computer security, designing a robust intrusion detection system is one of the most fundamental and important problems. In this paper, we propose a system-call language-modeling approach for designing anomaly-based host intrusion detection systems. To remedy the issue of high false-alarm rates commonly arising in conventional methods, we employ a novel ensemble method that blends multiple thresholding classifiers into a single one, making it possible to accumulate 'highly normal' sequences. The proposed system-call language model has various advantages leveraged by the fact that it can learn the semantic meaning and interactions of each system call that existing methods cannot effectively consider. Through diverse experiments on public benchmark datasets, we demonstrate the validity and effectiveness of the proposed method. Moreover, we show that our model possesses high portability, which is one of the key aspects of realizing successful intrusion detection systems.
[ "Gyuwan Kim, Hayoon Yi, Jangho Lee, Yunheung Paek, Sungroh Yoon", "['Gyuwan Kim' 'Hayoon Yi' 'Jangho Lee' 'Yunheung Paek' 'Sungroh Yoon']" ]
cs.PL cs.LG
null
1611.01752
null
null
http://arxiv.org/pdf/1611.01752v2
2017-06-25T16:32:21Z
2016-11-06T10:35:56Z
Learning a Static Analyzer from Data
To be practically useful, modern static analyzers must precisely model the effect of both, statements in the programming language as well as frameworks used by the program under analysis. While important, manually addressing these challenges is difficult for at least two reasons: (i) the effects on the overall analysis can be non-trivial, and (ii) as the size and complexity of modern libraries increase, so is the number of cases the analysis must handle. In this paper we present a new, automated approach for creating static analyzers: instead of manually providing the various inference rules of the analyzer, the key idea is to learn these rules from a dataset of programs. Our method consists of two ingredients: (i) a synthesis algorithm capable of learning a candidate analyzer from a given dataset, and (ii) a counter-example guided learning procedure which generates new programs beyond those in the initial dataset, critical for discovering corner cases and ensuring the learned analysis generalizes to unseen programs. We implemented and instantiated our approach to the task of learning JavaScript static analysis rules for a subset of points-to analysis and for allocation sites analysis. These are challenging yet important problems that have received significant research attention. We show that our approach is effective: our system automatically discovered practical and useful inference rules for many cases that are tricky to manually identify and are missed by state-of-the-art, manually tuned analyzers.
[ "Pavol Bielik, Veselin Raychev, Martin Vechev", "['Pavol Bielik' 'Veselin Raychev' 'Martin Vechev']" ]
cs.LG cs.AI cs.CV
null
1611.01779
null
null
http://arxiv.org/pdf/1611.01779v2
2017-02-14T19:47:46Z
2016-11-06T13:45:00Z
Learning to Act by Predicting the Future
We present an approach to sensorimotor control in immersive environments. Our approach utilizes a high-dimensional sensory stream and a lower-dimensional measurement stream. The cotemporal structure of these streams provides a rich supervisory signal, which enables training a sensorimotor control model by interacting with the environment. The model is trained using supervised learning techniques, but without extraneous supervision. It learns to act based on raw sensory input from a complex three-dimensional environment. The presented formulation enables learning without a fixed goal at training time, and pursuing dynamically changing goals at test time. We conduct extensive experiments in three-dimensional simulations based on the classical first-person game Doom. The results demonstrate that the presented approach outperforms sophisticated prior formulations, particularly on challenging tasks. The results also show that trained models successfully generalize across environments and goals. A model trained using the presented approach won the Full Deathmatch track of the Visual Doom AI Competition, which was held in previously unseen environments.
[ "['Alexey Dosovitskiy' 'Vladlen Koltun']", "Alexey Dosovitskiy and Vladlen Koltun" ]
cs.LG
null
1611.01787
null
null
http://arxiv.org/pdf/1611.01787v3
2017-06-28T15:04:46Z
2016-11-06T14:35:38Z
Learning to superoptimize programs
Code super-optimization is the task of transforming any given program to a more efficient version while preserving its input-output behaviour. In some sense, it is similar to the paraphrase problem from natural language processing where the intention is to change the syntax of an utterance without changing its semantics. Code-optimization has been the subject of years of research that has resulted in the development of rule-based transformation strategies that are used by compilers. More recently, however, a class of stochastic search based methods have been shown to outperform these strategies. This approach involves repeated sampling of modifications to the program from a proposal distribution, which are accepted or rejected based on whether they preserve correctness, and the improvement they achieve. These methods, however, neither learn from past behaviour nor do they try to leverage the semantics of the program under consideration. Motivated by this observation, we present a novel learning based approach for code super-optimization. Intuitively, our method works by learning the proposal distribution using unbiased estimators of the gradient of the expected improvement. Experiments on benchmarks comprising of automatically generated as well as existing ("Hacker's Delight") programs show that the proposed method is able to significantly outperform state of the art approaches for code super-optimization.
[ "Rudy Bunel, Alban Desmaison, M. Pawan Kumar, Philip H.S. Torr and\n Pushmeet Kohli", "['Rudy Bunel' 'Alban Desmaison' 'M. Pawan Kumar' 'Philip H. S. Torr'\n 'Pushmeet Kohli']" ]
cs.LG cs.NE
null
1611.01796
null
null
http://arxiv.org/pdf/1611.01796v2
2017-06-17T01:49:12Z
2016-11-06T15:36:56Z
Modular Multitask Reinforcement Learning with Policy Sketches
We describe a framework for multitask deep reinforcement learning guided by policy sketches. Sketches annotate tasks with sequences of named subtasks, providing information about high-level structural relationships among tasks but not how to implement them---specifically not providing the detailed guidance used by much previous work on learning policy abstractions for RL (e.g. intermediate rewards, subtask completion signals, or intrinsic motivations). To learn from sketches, we present a model that associates every subtask with a modular subpolicy, and jointly maximizes reward over full task-specific policies by tying parameters across shared subpolicies. Optimization is accomplished via a decoupled actor--critic training objective that facilitates learning common behaviors from multiple dissimilar reward functions. We evaluate the effectiveness of our approach in three environments featuring both discrete and continuous control, and with sparse rewards that can be obtained only after completing a number of high-level subgoals. Experiments show that using our approach to learn policies guided by sketches gives better performance than existing techniques for learning task-specific or shared policies, while naturally inducing a library of interpretable primitive behaviors that can be recombined to rapidly adapt to new tasks.
[ "['Jacob Andreas' 'Dan Klein' 'Sergey Levine']", "Jacob Andreas and Dan Klein and Sergey Levine" ]
cs.LG
null
1611.01799
null
null
http://arxiv.org/pdf/1611.01799v1
2016-11-06T16:04:48Z
2016-11-06T16:04:48Z
Generative Adversarial Networks as Variational Training of Energy Based Models
In this paper, we study deep generative models for effective unsupervised learning. We propose VGAN, which works by minimizing a variational lower bound of the negative log likelihood (NLL) of an energy based model (EBM), where the model density $p(\mathbf{x})$ is approximated by a variational distribution $q(\mathbf{x})$ that is easy to sample from. The training of VGAN takes a two step procedure: given $p(\mathbf{x})$, $q(\mathbf{x})$ is updated to maximize the lower bound; $p(\mathbf{x})$ is then updated one step with samples drawn from $q(\mathbf{x})$ to decrease the lower bound. VGAN is inspired by the generative adversarial networks (GANs), where $p(\mathbf{x})$ corresponds to the discriminator and $q(\mathbf{x})$ corresponds to the generator, but with several notable differences. We hence name our model variational GANs (VGANs). VGAN provides a practical solution to training deep EBMs in high dimensional space, by eliminating the need of MCMC sampling. From this view, we are also able to identify causes to the difficulty of training GANs and propose viable solutions. \footnote{Experimental code is available at https://github.com/Shuangfei/vgan}
[ "['Shuangfei Zhai' 'Yu Cheng' 'Rogerio Feris' 'Zhongfei Zhang']", "Shuangfei Zhai, Yu Cheng, Rogerio Feris, Zhongfei Zhang" ]
cs.LG stat.ML
null
1611.01838
null
null
http://arxiv.org/pdf/1611.01838v5
2017-04-21T07:16:30Z
2016-11-06T20:22:49Z
Entropy-SGD: Biasing Gradient Descent Into Wide Valleys
This paper proposes a new optimization algorithm called Entropy-SGD for training deep neural networks that is motivated by the local geometry of the energy landscape. Local extrema with low generalization error have a large proportion of almost-zero eigenvalues in the Hessian with very few positive or negative eigenvalues. We leverage upon this observation to construct a local-entropy-based objective function that favors well-generalizable solutions lying in large flat regions of the energy landscape, while avoiding poorly-generalizable solutions located in the sharp valleys. Conceptually, our algorithm resembles two nested loops of SGD where we use Langevin dynamics in the inner loop to compute the gradient of the local entropy before each update of the weights. We show that the new objective has a smoother energy landscape and show improved generalization over SGD using uniform stability, under certain assumptions. Our experiments on convolutional and recurrent networks demonstrate that Entropy-SGD compares favorably to state-of-the-art techniques in terms of generalization error and training time.
[ "['Pratik Chaudhari' 'Anna Choromanska' 'Stefano Soatto' 'Yann LeCun'\n 'Carlo Baldassi' 'Christian Borgs' 'Jennifer Chayes' 'Levent Sagun'\n 'Riccardo Zecchina']", "Pratik Chaudhari, Anna Choromanska, Stefano Soatto, Yann LeCun, Carlo\n Baldassi, Christian Borgs, Jennifer Chayes, Levent Sagun, Riccardo Zecchina" ]
stat.ML cs.AI cs.CV cs.LG cs.NE physics.soc-ph
null
1611.01843
null
null
http://arxiv.org/pdf/1611.01843v3
2017-08-17T19:51:29Z
2016-11-06T20:55:19Z
Learning to Perform Physics Experiments via Deep Reinforcement Learning
When encountering novel objects, humans are able to infer a wide range of physical properties such as mass, friction and deformability by interacting with them in a goal driven way. This process of active interaction is in the same spirit as a scientist performing experiments to discover hidden facts. Recent advances in artificial intelligence have yielded machines that can achieve superhuman performance in Go, Atari, natural language processing, and complex control problems; however, it is not clear that these systems can rival the scientific intuition of even a young child. In this work we introduce a basic set of tasks that require agents to estimate properties such as mass and cohesion of objects in an interactive simulated environment where they can manipulate the objects and observe the consequences. We found that state of art deep reinforcement learning methods can learn to perform the experiments necessary to discover such hidden properties. By systematically manipulating the problem difficulty and the cost incurred by the agent for performing experiments, we found that agents learn different strategies that balance the cost of gathering information against the cost of making mistakes in different situations.
[ "Misha Denil, Pulkit Agrawal, Tejas D Kulkarni, Tom Erez, Peter\n Battaglia, Nando de Freitas", "['Misha Denil' 'Pulkit Agrawal' 'Tejas D Kulkarni' 'Tom Erez'\n 'Peter Battaglia' 'Nando de Freitas']" ]
cs.LG
null
1611.01875
null
null
http://arxiv.org/pdf/1611.01875v1
2016-11-07T02:17:43Z
2016-11-07T02:17:43Z
Challenges of Feature Selection for Big Data Analytics
We are surrounded by huge amounts of large-scale high dimensional data. It is desirable to reduce the dimensionality of data for many learning tasks due to the curse of dimensionality. Feature selection has shown its effectiveness in many applications by building simpler and more comprehensive model, improving learning performance, and preparing clean, understandable data. Recently, some unique characteristics of big data such as data velocity and data variety present challenges to the feature selection problem. In this paper, we envision these challenges of feature selection for big data analytics. In particular, we first give a brief introduction about feature selection and then detail the challenges of feature selection for structured, heterogeneous and streaming data as well as its scalability and stability issues. At last, to facilitate and promote the feature selection research, we present an open-source feature selection repository (scikit-feature), which consists of most of current popular feature selection algorithms.
[ "Jundong Li, Huan Liu", "['Jundong Li' 'Huan Liu']" ]
cs.LG cs.AI cs.IT math.IT q-bio.NC stat.ML
null
1611.01886
null
null
http://arxiv.org/pdf/1611.01886v4
2017-03-10T16:41:16Z
2016-11-07T04:17:28Z
An Information-Theoretic Framework for Fast and Robust Unsupervised Learning via Neural Population Infomax
A framework is presented for unsupervised learning of representations based on infomax principle for large-scale neural populations. We use an asymptotic approximation to the Shannon's mutual information for a large neural population to demonstrate that a good initial approximation to the global information-theoretic optimum can be obtained by a hierarchical infomax method. Starting from the initial solution, an efficient algorithm based on gradient descent of the final objective function is proposed to learn representations from the input datasets, and the method works for complete, overcomplete, and undercomplete bases. As confirmed by numerical experiments, our method is robust and highly efficient for extracting salient features from input datasets. Compared with the main existing methods, our algorithm has a distinct advantage in both the training speed and the robustness of unsupervised representation learning. Furthermore, the proposed method is easily extended to the supervised or unsupervised model for training deep structure networks.
[ "Wentao Huang and Kechen Zhang", "['Wentao Huang' 'Kechen Zhang']" ]
stat.ML cs.LG
null
1611.01891
null
null
http://arxiv.org/pdf/1611.01891v1
2016-11-07T04:45:05Z
2016-11-07T04:45:05Z
Joint Multimodal Learning with Deep Generative Models
We investigate deep generative models that can exchange multiple modalities bi-directionally, e.g., generating images from corresponding texts and vice versa. Recently, some studies handle multiple modalities on deep generative models, such as variational autoencoders (VAEs). However, these models typically assume that modalities are forced to have a conditioned relation, i.e., we can only generate modalities in one direction. To achieve our objective, we should extract a joint representation that captures high-level concepts among all modalities and through which we can exchange them bi-directionally. As described herein, we propose a joint multimodal variational autoencoder (JMVAE), in which all modalities are independently conditioned on joint representation. In other words, it models a joint distribution of modalities. Furthermore, to be able to generate missing modalities from the remaining modalities properly, we develop an additional method, JMVAE-kl, that is trained by reducing the divergence between JMVAE's encoder and prepared networks of respective modalities. Our experiments show that our proposed method can obtain appropriate joint representation from multiple modalities and that it can generate and reconstruct them more properly than conventional VAEs. We further demonstrate that JMVAE can generate multiple modalities bi-directionally.
[ "Masahiro Suzuki, Kotaro Nakayama, Yutaka Matsuo", "['Masahiro Suzuki' 'Kotaro Nakayama' 'Yutaka Matsuo']" ]
cs.DB cs.LG
null
1611.01919
null
null
http://arxiv.org/pdf/1611.01919v2
2019-05-23T19:32:43Z
2016-11-07T07:13:27Z
Decision Tree Classification with Differential Privacy: A Survey
Data mining information about people is becoming increasingly important in the data-driven society of the 21st century. Unfortunately, sometimes there are real-world considerations that conflict with the goals of data mining; sometimes the privacy of the people being data mined needs to be considered. This necessitates that the output of data mining algorithms be modified to preserve privacy while simultaneously not ruining the predictive power of the outputted model. Differential privacy is a strong, enforceable definition of privacy that can be used in data mining algorithms, guaranteeing that nothing will be learned about the people in the data that could not already be discovered without their participation. In this survey, we focus on one particular data mining algorithm -- decision trees -- and how differential privacy interacts with each of the components that constitute decision tree algorithms. We analyze both greedy and random decision trees, and the conflicts that arise when trying to balance privacy requirements with the accuracy of the model.
[ "Sam Fletcher, Md Zahidul Islam", "['Sam Fletcher' 'Md Zahidul Islam']" ]
cs.AI cs.LG stat.ML
null
1611.01929
null
null
http://arxiv.org/pdf/1611.01929v4
2017-03-10T09:52:52Z
2016-11-07T08:12:53Z
Averaged-DQN: Variance Reduction and Stabilization for Deep Reinforcement Learning
Instability and variability of Deep Reinforcement Learning (DRL) algorithms tend to adversely affect their performance. Averaged-DQN is a simple extension to the DQN algorithm, based on averaging previously learned Q-values estimates, which leads to a more stable training procedure and improved performance by reducing approximation error variance in the target values. To understand the effect of the algorithm, we examine the source of value function estimation errors and provide an analytical comparison within a simplified model. We further present experiments on the Arcade Learning Environment benchmark that demonstrate significantly improved stability and performance due to the proposed extension.
[ "['Oron Anschel' 'Nir Baram' 'Nahum Shimkin']", "Oron Anschel, Nir Baram, Nahum Shimkin" ]
cs.LG cs.NE cs.NI
null
1611.01942
null
null
http://arxiv.org/pdf/1611.01942v2
2017-07-02T22:02:21Z
2016-11-07T09:10:06Z
DeepSense: A Unified Deep Learning Framework for Time-Series Mobile Sensing Data Processing
Mobile sensing applications usually require time-series inputs from sensors. Some applications, such as tracking, can use sensed acceleration and rate of rotation to calculate displacement based on physical system models. Other applications, such as activity recognition, extract manually designed features from sensor inputs for classification. Such applications face two challenges. On one hand, on-device sensor measurements are noisy. For many mobile applications, it is hard to find a distribution that exactly describes the noise in practice. Unfortunately, calculating target quantities based on physical system and noise models is only as accurate as the noise assumptions. Similarly, in classification applications, although manually designed features have proven to be effective, it is not always straightforward to find the most robust features to accommodate diverse sensor noise patterns and user behaviors. To this end, we propose DeepSense, a deep learning framework that directly addresses the aforementioned noise and feature customization challenges in a unified manner. DeepSense integrates convolutional and recurrent neural networks to exploit local interactions among similar mobile sensors, merge local interactions of different sensory modalities into global interactions, and extract temporal relationships to model signal dynamics. DeepSense thus provides a general signal estimation and classification framework that accommodates a wide range of applications. We demonstrate the effectiveness of DeepSense using three representative and challenging tasks: car tracking with motion sensors, heterogeneous human activity recognition, and user identification with biometric motion analysis. DeepSense significantly outperforms the state-of-the-art methods for all three tasks. In addition, DeepSense is feasible to implement on smartphones due to its moderate energy consumption and low latency
[ "['Shuochao Yao' 'Shaohan Hu' 'Yiran Zhao' 'Aston Zhang' 'Tarek Abdelzaher']", "Shuochao Yao, Shaohan Hu, Yiran Zhao, Aston Zhang, Tarek Abdelzaher" ]
stat.ML cs.LG
null
1611.01957
null
null
http://arxiv.org/pdf/1611.01957v3
2017-07-27T06:34:45Z
2016-11-07T09:38:12Z
Linear Convergence of SVRG in Statistical Estimation
SVRG and its variants are among the state of art optimization algorithms for large scale machine learning problems. It is well known that SVRG converges linearly when the objective function is strongly convex. However this setup can be restrictive, and does not include several important formulations such as Lasso, group Lasso, logistic regression, and some non-convex models including corrected Lasso and SCAD. In this paper, we prove that, for a class of statistical M-estimators covering examples mentioned above, SVRG solves the formulation with {\em a linear convergence rate} without strong convexity or even convexity. Our analysis makes use of {\em restricted strong convexity}, under which we show that SVRG converges linearly to the fundamental statistical precision of the model, i.e., the difference between true unknown parameter $\theta^*$ and the optimal solution $\hat{\theta}$ of the model.
[ "['Chao Qu' 'Yan Li' 'Huan Xu']", "Chao Qu, Yan Li, Huan Xu" ]
cs.LG
null
1611.01964
null
null
http://arxiv.org/pdf/1611.01964v1
2016-11-07T10:10:43Z
2016-11-07T10:10:43Z
Log-time and Log-space Extreme Classification
We present LTLS, a technique for multiclass and multilabel prediction that can perform training and inference in logarithmic time and space. LTLS embeds large classification problems into simple structured prediction problems and relies on efficient dynamic programming algorithms for inference. We train LTLS with stochastic gradient descent on a number of multiclass and multilabel datasets and show that despite its small memory footprint it is often competitive with existing approaches.
[ "['Kalina Jasinska' 'Nikos Karampatziakis']", "Kalina Jasinska, Nikos Karampatziakis" ]
cs.LG cs.NE
null
1611.01967
null
null
http://arxiv.org/pdf/1611.01967v2
2017-03-15T08:18:28Z
2016-11-07T10:15:40Z
Regularizing CNNs with Locally Constrained Decorrelations
Regularization is key for deep learning since it allows training more complex models while keeping lower levels of overfitting. However, the most prevalent regularizations do not leverage all the capacity of the models since they rely on reducing the effective number of parameters. Feature decorrelation is an alternative for using the full capacity of the models but the overfitting reduction margins are too narrow given the overhead it introduces. In this paper, we show that regularizing negatively correlated features is an obstacle for effective decorrelation and present OrthoReg, a novel regularization technique that locally enforces feature orthogonality. As a result, imposing locality constraints in feature decorrelation removes interferences between negatively correlated feature weights, allowing the regularizer to reach higher decorrelation bounds, and reducing the overfitting more effectively. In particular, we show that the models regularized with OrthoReg have higher accuracy bounds even when batch normalization and dropout are present. Moreover, since our regularization is directly performed on the weights, it is especially suitable for fully convolutional neural networks, where the weight space is constant compared to the feature map space. As a result, we are able to reduce the overfitting of state-of-the-art CNNs on CIFAR-10, CIFAR-100, and SVHN.
[ "Pau Rodr\\'iguez, Jordi Gonz\\`alez, Guillem Cucurull, Josep M. Gonfaus,\n Xavier Roca", "['Pau Rodríguez' 'Jordi Gonzàlez' 'Guillem Cucurull' 'Josep M. Gonfaus'\n 'Xavier Roca']" ]
stat.ML cs.LG
null
1611.01971
null
null
http://arxiv.org/pdf/1611.01971v3
2016-11-21T08:54:54Z
2016-11-07T10:25:15Z
One Class Splitting Criteria for Random Forests
Random Forests (RFs) are strong machine learning tools for classification and regression. However, they remain supervised algorithms, and no extension of RFs to the one-class setting has been proposed, except for techniques based on second-class sampling. This work fills this gap by proposing a natural methodology to extend standard splitting criteria to the one-class setting, structurally generalizing RFs to one-class classification. An extensive benchmark of seven state-of-the-art anomaly detection algorithms is also presented. This empirically demonstrates the relevance of our approach.
[ "Nicolas Goix (LTCI), Nicolas Drougard (ISAE), Romain Brault (LTCI),\n Ma\\\"el Chiapino (LTCI)", "['Nicolas Goix' 'Nicolas Drougard' 'Romain Brault' 'Maël Chiapino']" ]
cs.CV cs.LG
null
1611.01972
null
null
http://arxiv.org/pdf/1611.01972v2
2017-08-29T09:46:41Z
2016-11-07T10:26:41Z
Fixed-point Factorized Networks
In recent years, Deep Neural Networks (DNN) based methods have achieved remarkable performance in a wide range of tasks and have been among the most powerful and widely used techniques in computer vision. However, DNN-based methods are both computational-intensive and resource-consuming, which hinders the application of these methods on embedded systems like smart phones. To alleviate this problem, we introduce a novel Fixed-point Factorized Networks (FFN) for pretrained models to reduce the computational complexity as well as the storage requirement of networks. The resulting networks have only weights of -1, 0 and 1, which significantly eliminates the most resource-consuming multiply-accumulate operations (MACs). Extensive experiments on large-scale ImageNet classification task show the proposed FFN only requires one-thousandth of multiply operations with comparable accuracy.
[ "Peisong Wang and Jian Cheng", "['Peisong Wang' 'Jian Cheng']" ]
cs.PL cs.LG
null
1611.01988
null
null
http://arxiv.org/pdf/1611.01988v2
2017-03-02T13:26:11Z
2016-11-07T11:09:19Z
Differentiable Functional Program Interpreters
Programming by Example (PBE) is the task of inducing computer programs from input-output examples. It can be seen as a type of machine learning where the hypothesis space is the set of legal programs in some programming language. Recent work on differentiable interpreters relaxes the discrete space of programs into a continuous space so that search over programs can be performed using gradient-based optimization. While conceptually powerful, so far differentiable interpreter-based program synthesis has only been capable of solving very simple problems. In this work, we study modeling choices that arise when constructing a differentiable programming language and their impact on the success of synthesis. The main motivation for the modeling choices comes from functional programming: we study the effect of memory allocation schemes, immutable data, type systems, and built-in control-flow structures. Empirically we show that incorporating functional programming ideas into differentiable programming languages allows us to learn much more complex programs than is possible with existing differentiable languages.
[ "['John K. Feser' 'Marc Brockschmidt' 'Alexander L. Gaunt' 'Daniel Tarlow']", "John K. Feser, Marc Brockschmidt, Alexander L. Gaunt, Daniel Tarlow" ]
cs.LG
null
1611.01989
null
null
http://arxiv.org/pdf/1611.01989v2
2017-03-08T11:50:33Z
2016-11-07T11:09:45Z
DeepCoder: Learning to Write Programs
We develop a first line of attack for solving programming competition-style problems from input-output examples using deep learning. The approach is to train a neural network to predict properties of the program that generated the outputs from the inputs. We use the neural network's predictions to augment search techniques from the programming languages community, including enumerative search and an SMT-based solver. Empirically, we show that our approach leads to an order of magnitude speedup over the strong non-augmented baselines and a Recurrent Neural Network approach, and that we are able to solve problems of difficulty comparable to the simplest problems on programming competition websites.
[ "Matej Balog, Alexander L. Gaunt, Marc Brockschmidt, Sebastian Nowozin,\n Daniel Tarlow", "['Matej Balog' 'Alexander L. Gaunt' 'Marc Brockschmidt'\n 'Sebastian Nowozin' 'Daniel Tarlow']" ]
cs.LG
10.1007/978-3-319-71246-8_11
1611.02019
null
null
http://arxiv.org/abs/1611.02019v2
2019-04-17T11:38:13Z
2016-11-07T12:29:19Z
Multi-view Generative Adversarial Networks
Learning over multi-view data is a challenging problem with strong practical applications. Most related studies focus on the classification point of view and assume that all the views are available at any time. We consider an extension of this framework in two directions. First, based on the BiGAN model, the Multi-view BiGAN (MV-BiGAN) is able to perform density estimation from multi-view inputs. Second, it can deal with missing views and is able to update its prediction when additional views are provided. We illustrate these properties on a set of experiments over different datasets.
[ "Micka\\\"el Chen and Ludovic Denoyer", "['Mickaël Chen' 'Ludovic Denoyer']" ]
stat.ML cs.LG
null
1611.02041
null
null
http://arxiv.org/pdf/1611.02041v6
2018-07-22T07:49:28Z
2016-11-07T13:19:45Z
Does Distributionally Robust Supervised Learning Give Robust Classifiers?
Distributionally Robust Supervised Learning (DRSL) is necessary for building reliable machine learning systems. When machine learning is deployed in the real world, its performance can be significantly degraded because test data may follow a different distribution from training data. DRSL with f-divergences explicitly considers the worst-case distribution shift by minimizing the adversarially reweighted training loss. In this paper, we analyze this DRSL, focusing on the classification scenario. Since the DRSL is explicitly formulated for a distribution shift scenario, we naturally expect it to give a robust classifier that can aggressively handle shifted distributions. However, surprisingly, we prove that the DRSL just ends up giving a classifier that exactly fits the given training distribution, which is too pessimistic. This pessimism comes from two sources: the particular losses used in classification and the fact that the variety of distributions to which the DRSL tries to be robust is too wide. Motivated by our analysis, we propose simple DRSL that overcomes this pessimism and empirically demonstrate its effectiveness.
[ "Weihua Hu, Gang Niu, Issei Sato, Masashi Sugiyama", "['Weihua Hu' 'Gang Niu' 'Issei Sato' 'Masashi Sugiyama']" ]
cs.LG cs.AI stat.ML
null
1611.02047
null
null
http://arxiv.org/pdf/1611.02047v1
2016-11-07T13:43:38Z
2016-11-07T13:43:38Z
Reinforcement Learning Approach for Parallelization in Filters Aggregation Based Feature Selection Algorithms
One of the classical problems in machine learning and data mining is feature selection. A feature selection algorithm is expected to be quick, and at the same time it should show high performance. MeLiF algorithm effectively solves this problem using ensembles of ranking filters. This article describes two different ways to improve MeLiF algorithm performance with parallelization. Experiments show that proposed schemes significantly improves algorithm performance and increase feature selection quality.
[ "Ivan Smetannikov, Ilya Isaev, Andrey Filchenkov", "['Ivan Smetannikov' 'Ilya Isaev' 'Andrey Filchenkov']" ]
cs.LG cs.AI stat.ML
null
1611.02053
null
null
http://arxiv.org/pdf/1611.02053v1
2016-11-07T13:55:00Z
2016-11-07T13:55:00Z
Reinforcement-based Simultaneous Algorithm and its Hyperparameters Selection
Many algorithms for data analysis exist, especially for classification problems. To solve a data analysis problem, a proper algorithm should be chosen, and also its hyperparameters should be selected. In this paper, we present a new method for the simultaneous selection of an algorithm and its hyperparameters. In order to do so, we reduced this problem to the multi-armed bandit problem. We consider an algorithm as an arm and algorithm hyperparameters search during a fixed time as the corresponding arm play. We also suggest a problem-specific reward function. We performed the experiments on 10 real datasets and compare the suggested method with the existing one implemented in Auto-WEKA. The results show that our method is significantly better in most of the cases and never worse than the Auto-WEKA.
[ "Valeria Efimova, Andrey Filchenkov, Anatoly Shalyto", "['Valeria Efimova' 'Andrey Filchenkov' 'Anatoly Shalyto']" ]
stat.ML cs.DC cs.LG
null
1611.02101
null
null
http://arxiv.org/pdf/1611.02101v2
2017-06-26T13:35:23Z
2016-11-07T15:19:54Z
Distributed Coordinate Descent for Generalized Linear Models with Regularization
Generalized linear model with $L_1$ and $L_2$ regularization is a widely used technique for solving classification, class probability estimation and regression problems. With the numbers of both features and examples growing rapidly in the fields like text mining and clickstream data analysis parallelization and the use of cluster architectures becomes important. We present a novel algorithm for fitting regularized generalized linear models in the distributed environment. The algorithm splits data between nodes by features, uses coordinate descent on each node and line search to merge results globally. Convergence proof is provided. A modifications of the algorithm addresses slow node problem. For an important particular case of logistic regression we empirically compare our program with several state-of-the art approaches that rely on different algorithmic and data spitting methods. Experiments demonstrate that our approach is scalable and superior when training on large and sparse datasets.
[ "['Ilya Trofimov' 'Alexander Genkin']", "Ilya Trofimov, Alexander Genkin" ]
cs.LG
null
1611.02109
null
null
http://arxiv.org/pdf/1611.02109v2
2017-03-02T13:34:48Z
2016-11-07T15:25:53Z
Differentiable Programs with Neural Libraries
We develop a framework for combining differentiable programming languages with neural networks. Using this framework we create end-to-end trainable systems that learn to write interpretable algorithms with perceptual components. We explore the benefits of inductive biases for strong generalization and modularity that come from the program-like structure of our models. In particular, modularity allows us to learn a library of (neural) functions which grows and improves as more tasks are solved. Empirically, we show that this leads to lifelong learning systems that transfer knowledge to new tasks more effectively than baselines.
[ "Alexander L. Gaunt, Marc Brockschmidt, Nate Kushman, Daniel Tarlow", "['Alexander L. Gaunt' 'Marc Brockschmidt' 'Nate Kushman' 'Daniel Tarlow']" ]
cs.NE cs.LG
null
1611.0212
null
null
null
null
null
Neural Networks Designing Neural Networks: Multi-Objective Hyper-Parameter Optimization
Artificial neural networks have gone through a recent rise in popularity, achieving state-of-the-art results in various fields, including image classification, speech recognition, and automated control. Both the performance and computational complexity of such models are heavily dependant on the design of characteristic hyper-parameters (e.g., number of hidden layers, nodes per layer, or choice of activation functions), which have traditionally been optimized manually. With machine learning penetrating low-power mobile and embedded areas, the need to optimize not only for performance (accuracy), but also for implementation complexity, becomes paramount. In this work, we present a multi-objective design space exploration method that reduces the number of solution networks trained and evaluated through response surface modelling. Given spaces which can easily exceed 1020 solutions, manually designing a near-optimal architecture is unlikely as opportunities to reduce network complexity, while maintaining performance, may be overlooked. This problem is exacerbated by the fact that hyper-parameters which perform well on specific datasets may yield sub-par results on others, and must therefore be designed on a per-application basis. In our work, machine learning is leveraged by training an artificial neural network to predict the performance of future candidate networks. The method is evaluated on the MNIST and CIFAR-10 image datasets, optimizing for both recognition accuracy and computational complexity. Experimental results demonstrate that the proposed method can closely approximate the Pareto-optimal front, while only exploring a small fraction of the design space.
[ "Sean C. Smithson and Guang Yang and Warren J. Gross and Brett H. Meyer" ]
null
null
1611.02120
null
null
http://arxiv.org/pdf/1611.02120v1
2016-11-07T15:38:39Z
2016-11-07T15:38:39Z
Neural Networks Designing Neural Networks: Multi-Objective Hyper-Parameter Optimization
Artificial neural networks have gone through a recent rise in popularity, achieving state-of-the-art results in various fields, including image classification, speech recognition, and automated control. Both the performance and computational complexity of such models are heavily dependant on the design of characteristic hyper-parameters (e.g., number of hidden layers, nodes per layer, or choice of activation functions), which have traditionally been optimized manually. With machine learning penetrating low-power mobile and embedded areas, the need to optimize not only for performance (accuracy), but also for implementation complexity, becomes paramount. In this work, we present a multi-objective design space exploration method that reduces the number of solution networks trained and evaluated through response surface modelling. Given spaces which can easily exceed 1020 solutions, manually designing a near-optimal architecture is unlikely as opportunities to reduce network complexity, while maintaining performance, may be overlooked. This problem is exacerbated by the fact that hyper-parameters which perform well on specific datasets may yield sub-par results on others, and must therefore be designed on a per-application basis. In our work, machine learning is leveraged by training an artificial neural network to predict the performance of future candidate networks. The method is evaluated on the MNIST and CIFAR-10 image datasets, optimizing for both recognition accuracy and computational complexity. Experimental results demonstrate that the proposed method can closely approximate the Pareto-optimal front, while only exploring a small fraction of the design space.
[ "['Sean C. Smithson' 'Guang Yang' 'Warren J. Gross' 'Brett H. Meyer']" ]
cs.LG stat.ML
null
1611.02163
null
null
http://arxiv.org/pdf/1611.02163v4
2017-05-12T23:52:12Z
2016-11-07T16:42:09Z
Unrolled Generative Adversarial Networks
We introduce a method to stabilize Generative Adversarial Networks (GANs) by defining the generator objective with respect to an unrolled optimization of the discriminator. This allows training to be adjusted between using the optimal discriminator in the generator's objective, which is ideal but infeasible in practice, and using the current value of the discriminator, which is often unstable and leads to poor solutions. We show how this technique solves the common problem of mode collapse, stabilizes training of GANs with complex recurrent generators, and increases diversity and coverage of the data distribution by the generator.
[ "['Luke Metz' 'Ben Poole' 'David Pfau' 'Jascha Sohl-Dickstein']", "Luke Metz, Ben Poole, David Pfau, Jascha Sohl-Dickstein" ]
cs.LG
null
1611.02167
null
null
http://arxiv.org/pdf/1611.02167v3
2017-03-22T20:08:30Z
2016-11-07T16:49:43Z
Designing Neural Network Architectures using Reinforcement Learning
At present, designing convolutional neural network (CNN) architectures requires both human expertise and labor. New architectures are handcrafted by careful experimentation or modified from a handful of existing networks. We introduce MetaQNN, a meta-modeling algorithm based on reinforcement learning to automatically generate high-performing CNN architectures for a given learning task. The learning agent is trained to sequentially choose CNN layers using $Q$-learning with an $\epsilon$-greedy exploration strategy and experience replay. The agent explores a large but finite space of possible architectures and iteratively discovers designs with improved performance on the learning task. On image classification benchmarks, the agent-designed networks (consisting of only standard convolution, pooling, and fully-connected layers) beat existing networks designed with the same layer types and are competitive against the state-of-the-art methods that use more complex layer types. We also outperform existing meta-modeling approaches for network design on image classification tasks.
[ "['Bowen Baker' 'Otkrist Gupta' 'Nikhil Naik' 'Ramesh Raskar']", "Bowen Baker, Otkrist Gupta, Nikhil Naik and Ramesh Raskar" ]
stat.ML cs.LG
null
1611.02181
null
null
http://arxiv.org/pdf/1611.02181v1
2016-11-07T17:29:51Z
2016-11-07T17:29:51Z
Using Social Dynamics to Make Individual Predictions: Variational Inference with a Stochastic Kinetic Model
Social dynamics is concerned primarily with interactions among individuals and the resulting group behaviors, modeling the temporal evolution of social systems via the interactions of individuals within these systems. In particular, the availability of large-scale data from social networks and sensor networks offers an unprecedented opportunity to predict state-changing events at the individual level. Examples of such events include disease transmission, opinion transition in elections, and rumor propagation. Unlike previous research focusing on the collective effects of social systems, this study makes efficient inferences at the individual level. In order to cope with dynamic interactions among a large number of individuals, we introduce the stochastic kinetic model to capture adaptive transition probabilities and propose an efficient variational inference algorithm the complexity of which grows linearly --- rather than exponentially --- with the number of individuals. To validate this method, we have performed epidemic-dynamics experiments on wireless sensor network data collected from more than ten thousand people over three years. The proposed algorithm was used to track disease transmission and predict the probability of infection for each individual. Our results demonstrate that this method is more efficient than sampling while nonetheless achieving high accuracy.
[ "['Zhen Xu' 'Wen Dong' 'Sargur Srihari']", "Zhen Xu, Wen Dong and Sargur Srihari" ]
cs.LG
null
1611.02185
null
null
http://arxiv.org/pdf/1611.02185v5
2017-03-06T16:21:35Z
2016-11-07T17:41:20Z
Trusting SVM for Piecewise Linear CNNs
We present a novel layerwise optimization algorithm for the learning objective of Piecewise-Linear Convolutional Neural Networks (PL-CNNs), a large class of convolutional neural networks. Specifically, PL-CNNs employ piecewise linear non-linearities such as the commonly used ReLU and max-pool, and an SVM classifier as the final layer. The key observation of our approach is that the problem corresponding to the parameter estimation of a layer can be formulated as a difference-of-convex (DC) program, which happens to be a latent structured SVM. We optimize the DC program using the concave-convex procedure, which requires us to iteratively solve a structured SVM problem. This allows to design an optimization algorithm with an optimal learning rate that does not require any tuning. Using the MNIST, CIFAR and ImageNet data sets, we show that our approach always improves over the state of the art variants of backpropagation and scales to large data and large network settings.
[ "Leonard Berrada, Andrew Zisserman, M. Pawan Kumar", "['Leonard Berrada' 'Andrew Zisserman' 'M. Pawan Kumar']" ]
cs.LG
null
1611.02189
null
null
http://arxiv.org/pdf/1611.02189v2
2018-10-10T00:23:51Z
2016-11-07T17:49:49Z
CoCoA: A General Framework for Communication-Efficient Distributed Optimization
The scale of modern datasets necessitates the development of efficient distributed optimization methods for machine learning. We present a general-purpose framework for distributed computing environments, CoCoA, that has an efficient communication scheme and is applicable to a wide variety of problems in machine learning and signal processing. We extend the framework to cover general non-strongly-convex regularizers, including L1-regularized problems like lasso, sparse logistic regression, and elastic net regularization, and show how earlier work can be derived as a special case. We provide convergence guarantees for the class of convex regularized loss minimization objectives, leveraging a novel approach in handling non-strongly-convex regularizers and non-smooth loss functions. The resulting framework has markedly improved performance over state-of-the-art methods, as we illustrate with an extensive set of experiments on real distributed datasets.
[ "['Virginia Smith' 'Simone Forte' 'Chenxin Ma' 'Martin Takac'\n 'Michael I. Jordan' 'Martin Jaggi']", "Virginia Smith, Simone Forte, Chenxin Ma, Martin Takac, Michael I.\n Jordan, Martin Jaggi" ]
cs.LG cs.AI
null
1611.02205
null
null
http://arxiv.org/pdf/1611.02205v2
2017-02-07T18:50:50Z
2016-11-07T18:33:38Z
Playing SNES in the Retro Learning Environment
Mastering a video game requires skill, tactics and strategy. While these attributes may be acquired naturally by human players, teaching them to a computer program is a far more challenging task. In recent years, extensive research was carried out in the field of reinforcement learning and numerous algorithms were introduced, aiming to learn how to perform human tasks such as playing video games. As a result, the Arcade Learning Environment (ALE) (Bellemare et al., 2013) has become a commonly used benchmark environment allowing algorithms to train on various Atari 2600 games. In many games the state-of-the-art algorithms outperform humans. In this paper we introduce a new learning environment, the Retro Learning Environment --- RLE, that can run games on the Super Nintendo Entertainment System (SNES), Sega Genesis and several other gaming consoles. The environment is expandable, allowing for more video games and consoles to be easily added to the environment, while maintaining the same interface as ALE. Moreover, RLE is compatible with Python and Torch. SNES games pose a significant challenge to current algorithms due to their higher level of complexity and versatility.
[ "Nadav Bhonker, Shai Rozenberg and Itay Hubara", "['Nadav Bhonker' 'Shai Rozenberg' 'Itay Hubara']" ]
stat.ML cs.LG
null
1611.02221
null
null
http://arxiv.org/pdf/1611.02221v2
2017-03-06T19:13:07Z
2016-11-07T19:26:15Z
Minimax-optimal semi-supervised regression on unknown manifolds
We consider semi-supervised regression when the predictor variables are drawn from an unknown manifold. A simple two step approach to this problem is to: (i) estimate the manifold geodesic distance between any pair of points using both the labeled and unlabeled instances; and (ii) apply a k nearest neighbor regressor based on these distance estimates. We prove that given sufficiently many unlabeled points, this simple method of geodesic kNN regression achieves the optimal finite-sample minimax bound on the mean squared error, as if the manifold were known. Furthermore, we show how this approach can be efficiently implemented, requiring only O(k N log N) operations to estimate the regression function at all N labeled and unlabeled points. We illustrate this approach on two datasets with a manifold structure: indoor localization using WiFi fingerprints and facial pose estimation. In both cases, geodesic kNN is more accurate and much faster than the popular Laplacian eigenvector regressor.
[ "Amit Moscovich, Ariel Jaffe, Boaz Nadler", "['Amit Moscovich' 'Ariel Jaffe' 'Boaz Nadler']" ]
cs.LG
null
1611.02247
null
null
http://arxiv.org/pdf/1611.02247v3
2017-02-27T21:48:25Z
2016-11-07T20:09:16Z
Q-Prop: Sample-Efficient Policy Gradient with An Off-Policy Critic
Model-free deep reinforcement learning (RL) methods have been successful in a wide variety of simulated domains. However, a major obstacle facing deep RL in the real world is their high sample complexity. Batch policy gradient methods offer stable learning, but at the cost of high variance, which often requires large batches. TD-style methods, such as off-policy actor-critic and Q-learning, are more sample-efficient but biased, and often require costly hyperparameter sweeps to stabilize. In this work, we aim to develop methods that combine the stability of policy gradients with the efficiency of off-policy RL. We present Q-Prop, a policy gradient method that uses a Taylor expansion of the off-policy critic as a control variate. Q-Prop is both sample efficient and stable, and effectively combines the benefits of on-policy and off-policy methods. We analyze the connection between Q-Prop and existing model-free algorithms, and use control variate theory to derive two variants of Q-Prop with conservative and aggressive adaptation. We show that conservative Q-Prop provides substantial gains in sample efficiency over trust region policy optimization (TRPO) with generalized advantage estimation (GAE), and improves stability over deep deterministic policy gradient (DDPG), the state-of-the-art on-policy and off-policy methods, on OpenAI Gym's MuJoCo continuous control environments.
[ "['Shixiang Gu' 'Timothy Lillicrap' 'Zoubin Ghahramani' 'Richard E. Turner'\n 'Sergey Levine']", "Shixiang Gu and Timothy Lillicrap and Zoubin Ghahramani and Richard E.\n Turner and Sergey Levine" ]
cs.LG cs.AI stat.ML
null
1611.02252
null
null
http://arxiv.org/pdf/1611.02252v2
2017-10-26T01:23:40Z
2016-11-07T20:25:08Z
Hierarchical compositional feature learning
We introduce the hierarchical compositional network (HCN), a directed generative model able to discover and disentangle, without supervision, the building blocks of a set of binary images. The building blocks are binary features defined hierarchically as a composition of some of the features in the layer immediately below, arranged in a particular manner. At a high level, HCN is similar to a sigmoid belief network with pooling. Inference and learning in HCN are very challenging and existing variational approximations do not work satisfactorily. A main contribution of this work is to show that both can be addressed using max-product message passing (MPMP) with a particular schedule (no EM required). Also, using MPMP as an inference engine for HCN makes new tasks simple: adding supervision information, classifying images, or performing inpainting all correspond to clamping some variables of the model to their known values and running MPMP on the rest. When used for classification, fast inference with HCN has exactly the same functional form as a convolutional neural network (CNN) with linear activations and binary weights. However, HCN's features are qualitatively very different.
[ "Miguel L\\'azaro-Gredilla, Yi Liu, D. Scott Phoenix, Dileep George", "['Miguel Lázaro-Gredilla' 'Yi Liu' 'D. Scott Phoenix' 'Dileep George']" ]
stat.ML cs.LG
null
1611.02258
null
null
http://arxiv.org/pdf/1611.02258v2
2017-04-13T17:36:23Z
2016-11-07T20:36:56Z
Learning Time Series Detection Models from Temporally Imprecise Labels
In this paper, we consider a new low-quality label learning problem: learning time series detection models from temporally imprecise labels. In this problem, the data consist of a set of input time series, and supervision is provided by a sequence of noisy time stamps corresponding to the occurrence of positive class events. Such temporally imprecise labels commonly occur in areas like mobile health research where human annotators are tasked with labeling the occurrence of very short duration events. We propose a general learning framework for this problem that can accommodate different base classifiers and noise models. We present results on real mobile health data showing that the proposed framework significantly outperforms a number of alternatives including assuming that the label time stamps are noise-free, transforming the problem into the multiple instance learning framework, and learning on labels that were manually re-aligned.
[ "['Roy J. Adams' 'Benjamin M. Marlin']", "Roy J. Adams, Benjamin M. Marlin" ]
cs.CV cs.LG cs.NE
null
1611.02261
null
null
http://arxiv.org/pdf/1611.02261v4
2017-04-24T07:26:01Z
2016-11-07T20:50:08Z
Memory-augmented Attention Modelling for Videos
We present a method to improve video description generation by modeling higher-order interactions between video frames and described concepts. By storing past visual attention in the video associated to previously generated words, the system is able to decide what to look at and describe in light of what it has already looked at and described. This enables not only more effective local attention, but tractable consideration of the video sequence while generating each word. Evaluation on the challenging and popular MSVD and Charades datasets demonstrates that the proposed architecture outperforms previous video description approaches without requiring external temporal video features.
[ "['Rasool Fakoor' 'Abdel-rahman Mohamed' 'Margaret Mitchell'\n 'Sing Bing Kang' 'Pushmeet Kohli']", "Rasool Fakoor, Abdel-rahman Mohamed, Margaret Mitchell, Sing Bing\n Kang, Pushmeet Kohli" ]
stat.ML cs.AI cs.CL cs.LG
null
1611.02266
null
null
http://arxiv.org/pdf/1611.02266v2
2016-11-30T16:44:17Z
2016-11-07T20:57:24Z
Gaussian Attention Model and Its Application to Knowledge Base Embedding and Question Answering
We propose the Gaussian attention model for content-based neural memory access. With the proposed attention model, a neural network has the additional degree of freedom to control the focus of its attention from a laser sharp attention to a broad attention. It is applicable whenever we can assume that the distance in the latent space reflects some notion of semantics. We use the proposed attention model as a scoring function for the embedding of a knowledge base into a continuous vector space and then train a model that performs question answering about the entities in the knowledge base. The proposed attention model can handle both the propagation of uncertainty when following a series of relations and also the conjunction of conditions in a natural way. On a dataset of soccer players who participated in the FIFA World Cup 2014, we demonstrate that our model can handle both path queries and conjunctive queries well.
[ "['Liwen Zhang' 'John Winn' 'Ryota Tomioka']", "Liwen Zhang and John Winn and Ryota Tomioka" ]
cs.LG cs.AI stat.ML
null
1611.02268
null
null
http://arxiv.org/pdf/1611.02268v1
2016-11-07T20:58:58Z
2016-11-07T20:58:58Z
Optimal Binary Autoencoding with Pairwise Correlations
We formulate learning of a binary autoencoder as a biconvex optimization problem which learns from the pairwise correlations between encoded and decoded bits. Among all possible algorithms that use this information, ours finds the autoencoder that reconstructs its inputs with worst-case optimal loss. The optimal decoder is a single layer of artificial neurons, emerging entirely from the minimax loss minimization, and with weights learned by convex optimization. All this is reflected in competitive experimental results, demonstrating that binary autoencoding can be done efficiently by conveying information in pairwise correlations in an optimal fashion.
[ "Akshay Balsubramani", "['Akshay Balsubramani']" ]
cs.SI cs.LG stat.ML
null
1611.02305
null
null
http://arxiv.org/pdf/1611.02305v1
2016-11-07T21:28:40Z
2016-11-07T21:28:40Z
Learning Influence Functions from Incomplete Observations
We study the problem of learning influence functions under incomplete observations of node activations. Incomplete observations are a major concern as most (online and real-world) social networks are not fully observable. We establish both proper and improper PAC learnability of influence functions under randomly missing observations. Proper PAC learnability under the Discrete-Time Linear Threshold (DLT) and Discrete-Time Independent Cascade (DIC) models is established by reducing incomplete observations to complete observations in a modified graph. Our improper PAC learnability result applies for the DLT and DIC models as well as the Continuous-Time Independent Cascade (CIC) model. It is based on a parametrization in terms of reachability features, and also gives rise to an efficient and practical heuristic. Experiments on synthetic and real-world datasets demonstrate the ability of our method to compensate even for a fairly large fraction of missing observations.
[ "['Xinran He' 'Ke Xu' 'David Kempe' 'Yan Liu']", "Xinran He, Ke Xu, David Kempe and Yan Liu" ]
cs.LG cs.AI cs.CC cs.CR math.ST stat.TH
null
1611.02315
null
null
http://arxiv.org/pdf/1611.02315v2
2017-06-11T17:48:31Z
2016-11-07T21:43:39Z
Learning from Untrusted Data
The vast majority of theoretical results in machine learning and statistics assume that the available training data is a reasonably reliable reflection of the phenomena to be learned or estimated. Similarly, the majority of machine learning and statistical techniques used in practice are brittle to the presence of large amounts of biased or malicious data. In this work we consider two frameworks in which to study estimation, learning, and optimization in the presence of significant fractions of arbitrary data. The first framework, list-decodable learning, asks whether it is possible to return a list of answers, with the guarantee that at least one of them is accurate. For example, given a dataset of $n$ points for which an unknown subset of $\alpha n$ points are drawn from a distribution of interest, and no assumptions are made about the remaining $(1-\alpha)n$ points, is it possible to return a list of $\operatorname{poly}(1/\alpha)$ answers, one of which is correct? The second framework, which we term the semi-verified learning model, considers the extent to which a small dataset of trusted data (drawn from the distribution in question) can be leveraged to enable the accurate extraction of information from a much larger but untrusted dataset (of which only an $\alpha$-fraction is drawn from the distribution). We show strong positive results in both settings, and provide an algorithm for robust learning in a very general stochastic optimization setting. This general result has immediate implications for robust estimation in a number of settings, including for robustly estimating the mean of distributions with bounded second moments, robustly learning mixtures of such distributions, and robustly finding planted partitions in random graphs in which significant portions of the graph have been perturbed by an adversary.
[ "['Moses Charikar' 'Jacob Steinhardt' 'Gregory Valiant']", "Moses Charikar and Jacob Steinhardt and Gregory Valiant" ]
cs.NE cs.LG stat.ML
null
1611.0232
null
null
null
null
null
Adversarial Ladder Networks
The use of unsupervised data in addition to supervised data in training discriminative neural networks has improved the performance of this clas- sification scheme. However, the best results were achieved with a training process that is divided in two parts: first an unsupervised pre-training step is done for initializing the weights of the network and after these weights are refined with the use of supervised data. On the other hand adversarial noise has improved the results of clas- sical supervised learning. Recently, a new neural network topology called Ladder Network, where the key idea is based in some properties of hierar- chichal latent variable models, has been proposed as a technique to train a neural network using supervised and unsupervised data at the same time with what is called semi-supervised learning. This technique has reached state of the art classification. In this work we add adversarial noise to the ladder network and get state of the art classification, with several important conclusions on how adversarial noise can help in addition with new possible lines of investi- gation. We also propose an alternative to add adversarial noise to unsu- pervised data.
[ "Juan Maro\\~nas Molano, Alberto Albiol Colomer, Roberto Paredes\n Palacios" ]
null
null
1611.02320
null
null
http://arxiv.org/pdf/1611.02320v3
2018-04-27T08:16:36Z
2016-11-07T22:03:43Z
Adversarial Ladder Networks
The use of unsupervised data in addition to supervised data in training discriminative neural networks has improved the performance of this clas- sification scheme. However, the best results were achieved with a training process that is divided in two parts: first an unsupervised pre-training step is done for initializing the weights of the network and after these weights are refined with the use of supervised data. On the other hand adversarial noise has improved the results of clas- sical supervised learning. Recently, a new neural network topology called Ladder Network, where the key idea is based in some properties of hierar- chichal latent variable models, has been proposed as a technique to train a neural network using supervised and unsupervised data at the same time with what is called semi-supervised learning. This technique has reached state of the art classification. In this work we add adversarial noise to the ladder network and get state of the art classification, with several important conclusions on how adversarial noise can help in addition with new possible lines of investi- gation. We also propose an alternative to add adversarial noise to unsu- pervised data.
[ "['Juan Maroñas Molano' 'Alberto Albiol Colomer' 'Roberto Paredes Palacios']" ]
cs.LG cs.NE stat.ML
null
1611.02345
null
null
http://arxiv.org/pdf/1611.02345v3
2018-06-06T12:41:26Z
2016-11-07T23:47:05Z
Neural Taylor Approximations: Convergence and Exploration in Rectifier Networks
Modern convolutional networks, incorporating rectifiers and max-pooling, are neither smooth nor convex; standard guarantees therefore do not apply. Nevertheless, methods from convex optimization such as gradient descent and Adam are widely used as building blocks for deep learning algorithms. This paper provides the first convergence guarantee applicable to modern convnets, which furthermore matches a lower bound for convex nonsmooth functions. The key technical tool is the neural Taylor approximation -- a straightforward application of Taylor expansions to neural networks -- and the associated Taylor loss. Experiments on a range of optimizers, layers, and tasks provide evidence that the analysis accurately captures the dynamics of neural optimization. The second half of the paper applies the Taylor approximation to isolate the main difficulty in training rectifier nets -- that gradients are shattered -- and investigates the hypothesis that, by exploring the space of activation configurations more thoroughly, adaptive optimizers such as RMSProp and Adam are able to converge to better solutions.
[ "David Balduzzi, Brian McWilliams, Tony Butler-Yeoman", "['David Balduzzi' 'Brian McWilliams' 'Tony Butler-Yeoman']" ]
stat.ML cs.LG
null
1611.02365
null
null
http://arxiv.org/pdf/1611.02365v4
2018-08-26T19:23:06Z
2016-11-08T02:20:46Z
NonSTOP: A NonSTationary Online Prediction Method for Time Series
We present online prediction methods for time series that let us explicitly handle nonstationary artifacts (e.g. trend and seasonality) present in most real time series. Specifically, we show that applying appropriate transformations to such time series before prediction can lead to improved theoretical and empirical prediction performance. Moreover, since these transformations are usually unknown, we employ the learning with experts setting to develop a fully online method (NonSTOP-NonSTationary Online Prediction) for predicting nonstationary time series. This framework allows for seasonality and/or other trends in univariate time series and cointegration in multivariate time series. Our algorithms and regret analysis subsume recent related work while significantly expanding the applicability of such methods. For all the methods, we provide sub-linear regret bounds using relaxed assumptions. The theoretical guarantees do not fully capture the benefits of the transformations, thus we provide a data-dependent analysis of the follow-the-leader algorithm that provides insight into the success of using such transformations. We support all of our results with experiments on simulated and real data.
[ "['Christopher Xie' 'Avleen Bijral' 'Juan Lavista Ferres']", "Christopher Xie, Avleen Bijral, Juan Lavista Ferres" ]
cs.LG stat.ML
null
1611.02401
null
null
http://arxiv.org/pdf/1611.02401v7
2018-10-14T18:11:39Z
2016-11-08T06:07:25Z
Divide and Conquer Networks
We consider the learning of algorithmic tasks by mere observation of input-output pairs. Rather than studying this as a black-box discrete regression problem with no assumption whatsoever on the input-output mapping, we concentrate on tasks that are amenable to the principle of divide and conquer, and study what are its implications in terms of learning. This principle creates a powerful inductive bias that we leverage with neural architectures that are defined recursively and dynamically, by learning two scale-invariant atomic operations: how to split a given input into smaller sets, and how to merge two partially solved tasks into a larger partial solution. Our model can be trained in weakly supervised environments, namely by just observing input-output pairs, and in even weaker environments, using a non-differentiable reward signal. Moreover, thanks to the dynamic aspect of our architecture, we can incorporate the computational complexity as a regularization term that can be optimized by backpropagation. We demonstrate the flexibility and efficiency of the Divide-and-Conquer Network on several combinatorial and geometric tasks: convex hull, clustering, knapsack and euclidean TSP. Thanks to the dynamic programming nature of our model, we show significant improvements in terms of generalization error and computational complexity.
[ "['Alex Nowak-Vila' 'David Folqué' 'Joan Bruna']", "Alex Nowak-Vila, David Folqu\\'e and Joan Bruna" ]
cs.LG cs.NE
null
1611.02416
null
null
http://arxiv.org/pdf/1611.02416v2
2019-02-27T09:24:09Z
2016-11-08T07:41:54Z
An Efficient Approach to Boosting Performance of Deep Spiking Network Training
Nowadays deep learning is dominating the field of machine learning with state-of-the-art performance in various application areas. Recently, spiking neural networks (SNNs) have been attracting a great deal of attention, notably owning to their power efficiency, which can potentially allow us to implement a low-power deep learning engine suitable for real-time/mobile applications. However, implementing SNN-based deep learning remains challenging, especially gradient-based training of SNNs by error backpropagation. We cannot simply propagate errors through SNNs in conventional way because of the property of SNNs that process discrete data in the form of a series. Consequently, most of the previous studies employ a workaround technique, which first trains a conventional weighted-sum deep neural network and then maps the learning weights to the SNN under training, instead of training SNN parameters directly. In order to eliminate this workaround, recently proposed is a new class of SNN named deep spiking networks (DSNs), which can be trained directly (without a mapping from conventional deep networks) by error backpropagation with stochastic gradient descent. In this paper, we show that the initialization of the membrane potential on the backward path is an important step in DSN training, through diverse experiments performed under various conditions. Furthermore, we propose a simple and efficient method that can improve DSN training by controlling the initial membrane potential on the backward path. In our experiments, adopting the proposed approach allowed us to boost the performance of DSN training in terms of converging time and accuracy.
[ "Seongsik Park, Sang-gil Lee, Hyunha Nam, Sungroh Yoon", "['Seongsik Park' 'Sang-gil Lee' 'Hyunha Nam' 'Sungroh Yoon']" ]
cs.CV cs.LG
null
1611.02443
null
null
http://arxiv.org/pdf/1611.02443v2
2018-02-02T09:01:20Z
2016-11-08T09:29:17Z
Domain Adaptation with L2 constraints for classifying images from different endoscope systems
This paper proposes a method for domain adaptation that extends the maximum margin domain transfer (MMDT) proposed by Hoffman et al., by introducing L2 distance constraints between samples of different domains; thus, our method is denoted as MMDTL2. Motivated by the differences between the images taken by narrow band imaging (NBI) endoscopic devices, we utilize different NBI devices as different domains and estimate the transformations between samples of different domains, i.e., image samples taken by different NBI endoscope systems. We first formulate the problem in the primal form, and then derive the dual form with much lesser computational costs as compared to the naive approach. From our experimental results using NBI image datasets from two different NBI endoscopic devices, we find that MMDTL2 is better than MMDT and also support vector machines without adaptation, especially when NBI image features are high-dimensional and the per-class training samples are greater than 20.
[ "['Toru Tamaki' 'Shoji Sonoyama' 'Takio Kurita' 'Tsubasa Hirakawa'\n 'Bisser Raytchev' 'Kazufumi Kaneda' 'Tetsushi Koide' 'Shigeto Yoshida'\n 'Hiroshi Mieno' 'Shinji Tanaka' 'Kazuaki Chayama']", "Toru Tamaki, Shoji Sonoyama, Takio Kurita, Tsubasa Hirakawa, Bisser\n Raytchev, Kazufumi Kaneda, Tetsushi Koide, Shigeto Yoshida, Hiroshi Mieno,\n Shinji Tanaka, Kazuaki Chayama" ]
cs.AI cs.LG cs.NE
null
1611.02512
null
null
http://arxiv.org/pdf/1611.02512v1
2016-11-08T13:26:32Z
2016-11-08T13:26:32Z
Cognitive Discriminative Mappings for Rapid Learning
Humans can learn concepts or recognize items from just a handful of examples, while machines require many more samples to perform the same task. In this paper, we build a computational model to investigate the possibility of this kind of rapid learning. The proposed method aims to improve the learning task of input from sensory memory by leveraging the information retrieved from long-term memory. We present a simple and intuitive technique called cognitive discriminative mappings (CDM) to explore the cognitive problem. First, CDM separates and clusters the data instances retrieved from long-term memory into distinct classes with a discrimination method in working memory when a sensory input triggers the algorithm. CDM then maps each sensory data instance to be as close as possible to the median point of the data group with the same class. The experimental results demonstrate that the CDM approach is effective for learning the discriminative features of supervised classifications with few training sensory input instances.
[ "['Wen-Chieh Fang' 'Yi-ting Chiang']", "Wen-Chieh Fang and Yi-ting Chiang" ]
cs.LG
null
1611.02568
null
null
http://arxiv.org/pdf/1611.02568v3
2017-03-03T06:28:34Z
2016-11-08T15:50:27Z
PixelSNE: Visualizing Fast with Just Enough Precision via Pixel-Aligned Stochastic Neighbor Embedding
Embedding and visualizing large-scale high-dimensional data in a two-dimensional space is an important problem since such visualization can reveal deep insights out of complex data. Most of the existing embedding approaches, however, run on an excessively high precision, ignoring the fact that at the end, embedding outputs are converted into coarse-grained discrete pixel coordinates in a screen space. Motivated by such an observation and directly considering pixel coordinates in an embedding optimization process, we accelerate Barnes-Hut tree-based t-distributed stochastic neighbor embedding (BH-SNE), known as a state-of-the-art 2D embedding method, and propose a novel method called PixelSNE, a highly-efficient, screen resolution-driven 2D embedding method with a linear computational complexity in terms of the number of data items. Our experimental results show the significantly fast running time of PixelSNE by a large margin against BH-SNE, while maintaining the minimal degradation in the embedding quality. Finally, the source code of our method is publicly available at https://github.com/awesome-davian/PixelSNE
[ "Minjeong Kim, Minsuk Choi, Sunwoong Lee, Jian Tang, Haesun Park,\n Jaegul Choo", "['Minjeong Kim' 'Minsuk Choi' 'Sunwoong Lee' 'Jian Tang' 'Haesun Park'\n 'Jaegul Choo']" ]
cs.LG cs.CV
null
1611.02639
null
null
http://arxiv.org/pdf/1611.02639v2
2016-11-15T19:55:26Z
2016-11-08T18:10:44Z
Gradients of Counterfactuals
Gradients have been used to quantify feature importance in machine learning models. Unfortunately, in nonlinear deep networks, not only individual neurons but also the whole network can saturate, and as a result an important input feature can have a tiny gradient. We study various networks, and observe that this phenomena is indeed widespread, across many inputs. We propose to examine interior gradients, which are gradients of counterfactual inputs constructed by scaling down the original input. We apply our method to the GoogleNet architecture for object recognition in images, as well as a ligand-based virtual screening network with categorical features and an LSTM based language model for the Penn Treebank dataset. We visualize how interior gradients better capture feature importance. Furthermore, interior gradients are applicable to a wide variety of deep networks, and have the attribution property that the feature importance scores sum to the the prediction score. Best of all, interior gradients can be computed just as easily as gradients. In contrast, previous methods are complex to implement, which hinders practical adoption.
[ "Mukund Sundararajan, Ankur Taly, Qiqi Yan", "['Mukund Sundararajan' 'Ankur Taly' 'Qiqi Yan']" ]
cs.LG cs.NE stat.ML
null
1611.02648
null
null
http://arxiv.org/pdf/1611.02648v2
2017-01-13T17:53:10Z
2016-11-08T18:36:36Z
Deep Unsupervised Clustering with Gaussian Mixture Variational Autoencoders
We study a variant of the variational autoencoder model (VAE) with a Gaussian mixture as a prior distribution, with the goal of performing unsupervised clustering through deep generative models. We observe that the known problem of over-regularisation that has been shown to arise in regular VAEs also manifests itself in our model and leads to cluster degeneracy. We show that a heuristic called minimum information constraint that has been shown to mitigate this effect in VAEs can also be applied to improve unsupervised clustering performance with our model. Furthermore we analyse the effect of this heuristic and provide an intuition of the various processes with the help of visualizations. Finally, we demonstrate the performance of our model on synthetic data, MNIST and SVHN, showing that the obtained clusters are distinct, interpretable and result in achieving competitive performance on unsupervised clustering to the state-of-the-art results.
[ "['Nat Dilokthanakul' 'Pedro A. M. Mediano' 'Marta Garnelo'\n 'Matthew C. H. Lee' 'Hugh Salimbeni' 'Kai Arulkumaran' 'Murray Shanahan']", "Nat Dilokthanakul, Pedro A.M. Mediano, Marta Garnelo, Matthew C.H.\n Lee, Hugh Salimbeni, Kai Arulkumaran, Murray Shanahan" ]
cs.CL cs.AI cs.LG
null
1611.02654
null
null
http://arxiv.org/pdf/1611.02654v2
2017-12-22T02:36:08Z
2016-11-08T19:04:09Z
Sentence Ordering and Coherence Modeling using Recurrent Neural Networks
Modeling the structure of coherent texts is a key NLP problem. The task of coherently organizing a given set of sentences has been commonly used to build and evaluate models that understand such structure. We propose an end-to-end unsupervised deep learning approach based on the set-to-sequence framework to address this problem. Our model strongly outperforms prior methods in the order discrimination task and a novel task of ordering abstracts from scientific articles. Furthermore, our work shows that useful text representations can be obtained by learning to order sentences. Visualizing the learned sentence representations shows that the model captures high-level logical structure in paragraphs. Our representations perform comparably to state-of-the-art pre-training methods on sentence similarity and paraphrase detection tasks.
[ "['Lajanugen Logeswaran' 'Honglak Lee' 'Dragomir Radev']", "Lajanugen Logeswaran, Honglak Lee, Dragomir Radev" ]
cs.CL cs.LG cs.NE
null
1611.02683
null
null
http://arxiv.org/pdf/1611.02683v2
2018-02-22T01:57:27Z
2016-11-08T20:42:26Z
Unsupervised Pretraining for Sequence to Sequence Learning
This work presents a general unsupervised learning method to improve the accuracy of sequence to sequence (seq2seq) models. In our method, the weights of the encoder and decoder of a seq2seq model are initialized with the pretrained weights of two language models and then fine-tuned with labeled data. We apply this method to challenging benchmarks in machine translation and abstractive summarization and find that it significantly improves the subsequent supervised models. Our main result is that pretraining improves the generalization of seq2seq models. We achieve state-of-the art results on the WMT English$\rightarrow$German task, surpassing a range of methods using both phrase-based machine translation and neural machine translation. Our method achieves a significant improvement of 1.3 BLEU from the previous best models on both WMT'14 and WMT'15 English$\rightarrow$German. We also conduct human evaluations on abstractive summarization and find that our method outperforms a purely supervised learning baseline in a statistically significant manner.
[ "Prajit Ramachandran, Peter J. Liu, Quoc V. Le", "['Prajit Ramachandran' 'Peter J. Liu' 'Quoc V. Le']" ]
cs.LG stat.ML
null
1611.02731
null
null
http://arxiv.org/pdf/1611.02731v2
2017-03-04T06:19:22Z
2016-11-08T21:43:34Z
Variational Lossy Autoencoder
Representation learning seeks to expose certain aspects of observed data in a learned representation that's amenable to downstream tasks like classification. For instance, a good representation for 2D images might be one that describes only global structure and discards information about detailed texture. In this paper, we present a simple but principled method to learn such global representations by combining Variational Autoencoder (VAE) with neural autoregressive models such as RNN, MADE and PixelRNN/CNN. Our proposed VAE model allows us to have control over what the global latent code can learn and , by designing the architecture accordingly, we can force the global latent code to discard irrelevant information such as texture in 2D images, and hence the VAE only "autoencodes" data in a lossy fashion. In addition, by leveraging autoregressive models as both prior distribution $p(z)$ and decoding distribution $p(x|z)$, we can greatly improve generative modeling performance of VAEs, achieving new state-of-the-art results on MNIST, OMNIGLOT and Caltech-101 Silhouettes density estimation tasks.
[ "['Xi Chen' 'Diederik P. Kingma' 'Tim Salimans' 'Yan Duan'\n 'Prafulla Dhariwal' 'John Schulman' 'Ilya Sutskever' 'Pieter Abbeel']", "Xi Chen, Diederik P. Kingma, Tim Salimans, Yan Duan, Prafulla\n Dhariwal, John Schulman, Ilya Sutskever, Pieter Abbeel" ]
cs.LG math.DS
null
1611.02739
null
null
http://arxiv.org/pdf/1611.02739v4
2017-03-23T18:40:46Z
2016-11-08T22:09:22Z
Recursive Regression with Neural Networks: Approximating the HJI PDE Solution
The majority of methods used to compute approximations to the Hamilton-Jacobi-Isaacs partial differential equation (HJI PDE) rely on the discretization of the state space to perform dynamic programming updates. This type of approach is known to suffer from the curse of dimensionality due to the exponential growth in grid points with the state dimension. In this work we present an approximate dynamic programming algorithm that computes an approximation of the solution of the HJI PDE by alternating between solving a regression problem and solving a minimax problem using a feedforward neural network as the function approximator. We find that this method requires less memory to run and to store the approximation than traditional gridding methods, and we test it on a few systems of two, three and six dimensions.
[ "['Vicenç Rubies-Royo' 'Claire Tomlin']", "Vicen\\c{c} Rubies-Royo, Claire Tomlin" ]
cs.AI cs.LG stat.ML
null
1611.02755
null
null
http://arxiv.org/pdf/1611.02755v1
2016-11-08T22:52:08Z
2016-11-08T22:52:08Z
Recursive Decomposition for Nonconvex Optimization
Continuous optimization is an important problem in many areas of AI, including vision, robotics, probabilistic inference, and machine learning. Unfortunately, most real-world optimization problems are nonconvex, causing standard convex techniques to find only local optima, even with extensions like random restarts and simulated annealing. We observe that, in many cases, the local modes of the objective function have combinatorial structure, and thus ideas from combinatorial optimization can be brought to bear. Based on this, we propose a problem-decomposition approach to nonconvex optimization. Similarly to DPLL-style SAT solvers and recursive conditioning in probabilistic inference, our algorithm, RDIS, recursively sets variables so as to simplify and decompose the objective function into approximately independent sub-functions, until the remaining functions are simple enough to be optimized by standard techniques like gradient descent. The variables to set are chosen by graph partitioning, ensuring decomposition whenever possible. We show analytically that RDIS can solve a broad class of nonconvex optimization problems exponentially faster than gradient descent with random restarts. Experimentally, RDIS outperforms standard techniques on problems like structure from motion and protein folding.
[ "['Abram L. Friesen' 'Pedro Domingos']", "Abram L. Friesen and Pedro Domingos" ]
cs.LG
null
1611.0277
null
null
null
null
null
Delving into Transferable Adversarial Examples and Black-box Attacks
An intriguing property of deep neural networks is the existence of adversarial examples, which can transfer among different architectures. These transferable adversarial examples may severely hinder deep neural network-based applications. Previous works mostly study the transferability using small scale datasets. In this work, we are the first to conduct an extensive study of the transferability over large models and a large scale dataset, and we are also the first to study the transferability of targeted adversarial examples with their target labels. We study both non-targeted and targeted adversarial examples, and show that while transferable non-targeted adversarial examples are easy to find, targeted adversarial examples generated using existing approaches almost never transfer with their target labels. Therefore, we propose novel ensemble-based approaches to generating transferable adversarial examples. Using such approaches, we observe a large proportion of targeted adversarial examples that are able to transfer with their target labels for the first time. We also present some geometric studies to help understanding the transferable adversarial examples. Finally, we show that the adversarial examples generated using ensemble-based approaches can successfully attack Clarifai.com, which is a black-box image classification system.
[ "Yanpei Liu, Xinyun Chen, Chang Liu, Dawn Song" ]
null
null
1611.02770
null
null
http://arxiv.org/pdf/1611.02770v3
2017-02-07T14:24:44Z
2016-11-08T23:25:00Z
Delving into Transferable Adversarial Examples and Black-box Attacks
An intriguing property of deep neural networks is the existence of adversarial examples, which can transfer among different architectures. These transferable adversarial examples may severely hinder deep neural network-based applications. Previous works mostly study the transferability using small scale datasets. In this work, we are the first to conduct an extensive study of the transferability over large models and a large scale dataset, and we are also the first to study the transferability of targeted adversarial examples with their target labels. We study both non-targeted and targeted adversarial examples, and show that while transferable non-targeted adversarial examples are easy to find, targeted adversarial examples generated using existing approaches almost never transfer with their target labels. Therefore, we propose novel ensemble-based approaches to generating transferable adversarial examples. Using such approaches, we observe a large proportion of targeted adversarial examples that are able to transfer with their target labels for the first time. We also present some geometric studies to help understanding the transferable adversarial examples. Finally, we show that the adversarial examples generated using ensemble-based approaches can successfully attack Clarifai.com, which is a black-box image classification system.
[ "['Yanpei Liu' 'Xinyun Chen' 'Chang Liu' 'Dawn Song']" ]
cs.AI cs.LG cs.NE stat.ML
null
1611.02779
null
null
http://arxiv.org/pdf/1611.02779v2
2016-11-10T01:17:36Z
2016-11-09T00:13:29Z
RL$^2$: Fast Reinforcement Learning via Slow Reinforcement Learning
Deep reinforcement learning (deep RL) has been successful in learning sophisticated behaviors automatically; however, the learning process requires a huge number of trials. In contrast, animals can learn new tasks in just a few trials, benefiting from their prior knowledge about the world. This paper seeks to bridge this gap. Rather than designing a "fast" reinforcement learning algorithm, we propose to represent it as a recurrent neural network (RNN) and learn it from data. In our proposed method, RL$^2$, the algorithm is encoded in the weights of the RNN, which are learned slowly through a general-purpose ("slow") RL algorithm. The RNN receives all information a typical RL algorithm would receive, including observations, actions, rewards, and termination flags; and it retains its state across episodes in a given Markov Decision Process (MDP). The activations of the RNN store the state of the "fast" RL algorithm on the current (previously unseen) MDP. We evaluate RL$^2$ experimentally on both small-scale and large-scale problems. On the small-scale side, we train it to solve randomly generated multi-arm bandit problems and finite MDPs. After RL$^2$ is trained, its performance on new MDPs is close to human-designed algorithms with optimality guarantees. On the large-scale side, we test RL$^2$ on a vision-based navigation task and show that it scales up to high-dimensional problems.
[ "Yan Duan, John Schulman, Xi Chen, Peter L. Bartlett, Ilya Sutskever,\n Pieter Abbeel", "['Yan Duan' 'John Schulman' 'Xi Chen' 'Peter L. Bartlett' 'Ilya Sutskever'\n 'Pieter Abbeel']" ]
cs.LG cs.AI
null
1611.02796
null
null
http://arxiv.org/pdf/1611.02796v9
2017-10-16T21:31:31Z
2016-11-09T01:46:32Z
Sequence Tutor: Conservative Fine-Tuning of Sequence Generation Models with KL-control
This paper proposes a general method for improving the structure and quality of sequences generated by a recurrent neural network (RNN), while maintaining information originally learned from data, as well as sample diversity. An RNN is first pre-trained on data using maximum likelihood estimation (MLE), and the probability distribution over the next token in the sequence learned by this model is treated as a prior policy. Another RNN is then trained using reinforcement learning (RL) to generate higher-quality outputs that account for domain-specific incentives while retaining proximity to the prior policy of the MLE RNN. To formalize this objective, we derive novel off-policy RL methods for RNNs from KL-control. The effectiveness of the approach is demonstrated on two applications; 1) generating novel musical melodies, and 2) computational molecular generation. For both problems, we show that the proposed method improves the desired properties and structure of the generated sequences, while maintaining information learned from data.
[ "Natasha Jaques, Shixiang Gu, Dzmitry Bahdanau, Jos\\'e Miguel\n Hern\\'andez-Lobato, Richard E. Turner, Douglas Eck", "['Natasha Jaques' 'Shixiang Gu' 'Dzmitry Bahdanau'\n 'José Miguel Hernández-Lobato' 'Richard E. Turner' 'Douglas Eck']" ]
cs.LG
null
1611.0283
null
null
null
null
null
Online Learning for Wireless Distributed Computing
There has been a growing interest for Wireless Distributed Computing (WDC), which leverages collaborative computing over multiple wireless devices. WDC enables complex applications that a single device cannot support individually. However, the problem of assigning tasks over multiple devices becomes challenging in the dynamic environments encountered in real-world settings, considering that the resource availability and channel conditions change over time in unpredictable ways due to mobility and other factors. In this paper, we formulate a task assignment problem as an online learning problem using an adversarial multi-armed bandit framework. We propose MABSTA, a novel online learning algorithm that learns the performance of unknown devices and channel qualities continually through exploratory probing and makes task assignment decisions by exploiting the gained knowledge. For maximal adaptability, MABSTA is designed to make no stochastic assumption about the environment. We analyze it mathematically and provide a worst-case performance guarantee for any dynamic environment. We also compare it with the optimal offline policy as well as other baselines via emulations on trace-data obtained from a wireless IoT testbed, and show that it offers competitive and robust performance in all cases. To the best of our knowledge, MABSTA is the first online algorithm in this domain of task assignment problems and provides provable performance guarantee.
[ "Yi-Hsuan Kao, Kwame Wright, Bhaskar Krishnamachari, Fan Bai" ]