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Artificial Intelligence, Machine Learning and Big Data - A Comprehensive Report

#artificialintelligence

Artificial Intelligence and Machine Learning are the hottest jobs in the industry right now. For instance, did you know that more than 50,000 positions related to Data and Analytics are currently vacant in India? We are excited to release a comprehensive report together with Great Learning on how AI, ML and Big Data are changing and evolving the world around us. Additionally, this report aims to provide an overview of the kind of career opportunities available in these fields right now, and the different roles we might see in the future. The aim behind creating this report is to provide our Data Science community with the context of changes happening at a macro level, and how they can best prepare for these upcoming changes. So, if you are already a Data Science professional or want to get into Data Science, we expect this report to be useful in providing you a context and preparing you for the future.


The Latest Battleground for Chipmakers: Self-Driving Cars

WIRED

It may be a long time before you can own a truly self-driving car. But chipmakers are placing bets that you will. On Tuesday, the Japanese chipmaker Renesas, the second-largest provider of semiconductors for the automotive industry, said it will acquire San Jose based chipmaker Integrated Device Technology (IDT) for $6.7 billion, in part to prepare for autonomous vehicles. IDT has not historically provided chips for cars, but it does have sensor and wireless technologies that could help Renesas compete in the market for chips for autonomous vehicles. "Renesas and IDT have complementary technologies," says Objective Analysis analyst Jim Handy.


Discretely Relaxing Continuous Variables for tractable Variational Inference

arXiv.org Machine Learning

We explore a new research direction in Bayesian variational inference with discrete latent variable priors where we exploit Kronecker matrix algebra for efficient and exact computations of the evidence lower bound (ELBO). The proposed "DIRECT" approach has several advantages over its predecessors; (i) it can exactly compute ELBO gradients (i.e. unbiased, zero-variance gradient estimates), eliminating the need for high-variance stochastic gradient estimators and enabling the use of quasi-Newton optimization methods; (ii) its training complexity is independent of the number of training points, permitting inference on large datasets; and (iii) its posterior samples consist of sparse and low-precision quantized integers which permit fast inference on hardware limited devices. In addition, our DIRECT models can exactly compute statistical moments of the parameterized predictive posterior without relying on Monte Carlo sampling. Our numerical studies demonstrate accurate inference using latent variables discretized as extremely low-precision 4-bit quantized integers. While the ELBO computations considered require over $10^{2352}$ log-likelihood evaluations, we train on datasets with over two-million points in just seconds.


The Inductive Bias of Restricted f-GANs

arXiv.org Machine Learning

Generative adversarial networks are a novel method for statistical inference that have achieved much empirical success; however, the factors contributing to this success remain ill-understood. In this work, we attempt to analyze generative adversarial learning -- that is, statistical inference as the result of a game between a generator and a discriminator -- with the view of understanding how it differs from classical statistical inference solutions such as maximum likelihood inference and the method of moments. Specifically, we provide a theoretical characterization of the distribution inferred by a simple form of generative adversarial learning called restricted f-GANs -- where the discriminator is a function in a given function class, the distribution induced by the generator is restricted to lie in a pre-specified distribution class and the objective is similar to a variational form of the f-divergence. A consequence of our result is that for linear KL-GANs -- that is, when the discriminator is a linear function over some feature space and f corresponds to the KL-divergence -- the distribution induced by the optimal generator is neither the maximum likelihood nor the method of moments solution, but an interesting combination of both.


Distilled Wasserstein Learning for Word Embedding and Topic Modeling

arXiv.org Machine Learning

We propose a novel Wasserstein method with a distillation mechanism, yielding joint learning of word embeddings and topics. The proposed method is based on the fact that the Euclidean distance between word embeddings may be employed as the underlying distance in the Wasserstein topic model. The word distributions of topics, their optimal transports to the word distributions of documents, and the embeddings of words are learned in a unified framework. When learning the topic model, we leverage a distilled underlying distance matrix to update the topic distributions and smoothly calculate the corresponding optimal transports. Such a strategy provides the updating of word embeddings with robust guidance, improving the algorithmic convergence. As an application, we focus on patient admission records, in which the proposed method embeds the codes of diseases and procedures and learns the topics of admissions, obtaining superior performance on clinically-meaningful disease network construction, mortality prediction as a function of admission codes, and procedure recommendation.


Hyperprior Induced Unsupervised Disentanglement of Latent Representations

arXiv.org Machine Learning

We address the problem of unsupervised disentanglement of latent representations learnt via deep generative models. In contrast to current approaches that operate on the evidence lower bound (ELBO), we argue that statistical independence in the latent space of VAEs can be enforced in a principled hierarchical Bayesian manner. To this effect, we augment the standard VAE with an inverse-Wishart (IW) prior on the covariance matrix of the latent code. By tuning the IW parameters, we are able to encourage (or discourage) independence in the learnt latent dimensions. Extensive experimental results on a range of datasets (2DShapes, 3DChairs, 3DFaces and CelebA) show our approach to outperform the $\beta$-VAE and is competitive with the state-of-the-art FactorVAE. Our approach achieves significantly better disentanglement and reconstruction on a new dataset (CorrelatedEllipses) which introduces correlations between the factors of variation.


Benchmarking and Optimization of Gradient Boosted Decision Tree Algorithms

arXiv.org Machine Learning

Abstract--Gradient boosted decision trees (GBDTs) have seen widespread adoption in academia, industry and competitive data science due to their state-of-the-art performance in a wide variety of machine learning tasks. In this paper, we present an extensive empirical comparison of XGBoost, LightGBM and CatBoost, three popular GBDT algorithms, to aid the data science practitioner in the choice from the multitude of available implementations. Specifically, we evaluate their behavior on four largescale datasets with varying shapes, sparsities and learning tasks, in order to evaluate the algorithms' generalization performance, training times (on both CPU and GPU) and their sensitivity to hyper-parameter tuning. In our analysis, we first make use of a distributed grid-search to benchmark the algorithms on fixed configurations, and then employ a state-of-the-art algorithm for Bayesian hyper-parameter optimization to fine-tune the models. Many powerful techniques in machine learning involve constructing a strong learner from a number of weak learners. One such approach, known as bagging, combines the predictions of a large number of weak learners, each using a different bootstrap sample of the training data set [1]. It has been shown that such a an approach can reduce variance and produce a strong learner. An alternative approach, known as boosting, involves iteratively training a sequence of weak learners, whereby the training examples for the next learner are weighted according to the success of the previouslyconstructed learners.


Are You Sure You Want To Do That? Classification with Verification

arXiv.org Machine Learning

Classification systems typically act in isolation, meaning they are required to implicitly memorize the characteristics of all candidate classes in order to classify. The cost of this is increased memory usage and poor sample efficiency. We propose a model which instead verifies using reference images during the classification process, reducing the burden of memorization. The model uses iterative nondifferentiable queries in order to classify an image. We demonstrate that such a model is feasible to train and can match baseline accuracy while being more parameter efficient. However, we show that finding the correct balance between image recognition and verification is essential to pushing the model towards desired behavior, suggesting that a pipeline of recognition followed by verification is a more promising approach.


Weakly-Supervised Neural Text Classification

arXiv.org Machine Learning

Deep neural networks are gaining increasing popularity for the classic text classification task, due to their strong expressive power and less requirement for feature engineering. Despite such attractiveness, neural text classification models suffer from the lack of training data in many real-world applications. Although many semi-supervised and weakly-supervised text classification models exist, they cannot be easily applied to deep neural models and meanwhile support limited supervision types. In this paper, we propose a weakly-supervised method that addresses the lack of training data in neural text classification. Our method consists of two modules: (1) a pseudo-document generator that leverages seed information to generate pseudo-labeled documents for model pre-training, and (2) a self-training module that bootstraps on real unlabeled data for model refinement. Our method has the flexibility to handle different types of weak supervision and can be easily integrated into existing deep neural models for text classification. We have performed extensive experiments on three real-world datasets from different domains. The results demonstrate that our proposed method achieves inspiring performance without requiring excessive training data and outperforms baseline methods significantly.


Creating Fair Models of Atherosclerotic Cardiovascular Disease Risk

arXiv.org Machine Learning

Guidelines for the management of atherosclerotic cardiovascular disease (ASCVD) recommend the use of risk stratification models to identify patients most likely to benefit from cholesterol-lowering and other therapies. These models have differential performance across race and gender groups with inconsistent behavior across studies, potentially resulting in an inequitable distribution of beneficial therapy. In this work, we leverage adversarial learning and a large observational cohort extracted from electronic health records (EHRs) to develop a "fair" ASCVD risk prediction model with reduced variability in error rates across groups. We empirically demonstrate that our approach is capable of aligning the distribution of risk predictions conditioned on the outcome across several groups simultaneously for models built from high-dimensional EHR data. We also discuss the relevance of these results in the context of the empirical trade-off between fairness and model performance.