Bayesian Learning
Causal Falling Rule Lists
A causal falling rule list (CFRL) is a sequence of if-then rules that specifies heterogeneous treatment effects, where (i) the order of rules determines the treatment effect subgroup a subject belongs to, and (ii) the treatment effect decreases monotonically down the list. A given CFRL parameterizes a hierarchical bayesian regression model in which the treatment effects are incorporated as parameters, and assumed constant within model-specific subgroups. We formulate the search for the CFRL best supported by the data as a Bayesian model selection problem, where we perform a search over the space of CFRL models, and approximate the evidence for a given CFRL model using standard variational techniques. We apply CFRL to a census wage dataset to identify subgroups of differing wage inequalities between men and women.
Learning Deep Energy Models: Contrastive Divergence vs. Amortized MLE
We propose a number of new algorithms for learning deep energy models from data motivated by a recent Stein variational gradient descent (SVGD) algorithm, including a Stein contrastive divergence (SteinCD) that integrates CD with SVGD based on their theoretical connections, and a SteinGAN that trains an auxiliary generator to generate the negative samples in maximum likelihood estimation (MLE). We demonstrate that our SteinCD trains models with good generalization (high test likelihood), while Stein-GAN can generate realistic looking images competitive with GAN-style methods. We show that by combing SteinCD and SteinGAN, it is possible to inherent the advantage of both approaches.
A Minimax Approach to Supervised Learning
Given a task of predicting $Y$ from $X$, a loss function $L$, and a set of probability distributions $\Gamma$ on $(X,Y)$, what is the optimal decision rule minimizing the worst-case expected loss over $\Gamma$? In this paper, we address this question by introducing a generalization of the principle of maximum entropy. Applying this principle to sets of distributions with marginal on $X$ constrained to be the empirical marginal from the data, we develop a general minimax approach for supervised learning problems. While for some loss functions such as squared-error and log loss, the minimax approach rederives well-knwon regression models, for the 0-1 loss it results in a new linear classifier which we call the maximum entropy machine. The maximum entropy machine minimizes the worst-case 0-1 loss over the structured set of distribution, and by our numerical experiments can outperform other well-known linear classifiers such as SVM. We also prove a bound on the generalization worst-case error in the minimax approach.
Survey on Models and Techniques for Root-Cause Analysis
Solé, Marc, Muntés-Mulero, Victor, Rana, Annie Ibrahim, Estrada, Giovani
Automation and computer intelligence to support complex human decisions becomes essential to manage large and distributed systems in the Cloud and IoT era. Understanding the root cause of an observed symptom in a complex system has been a major problem for decades. As industry dives into the IoT world and the amount of data generated per year grows at an amazing speed, an important question is how to find appropriate mechanisms to determine root causes that can handle huge amounts of data or may provide valuable feedback in real-time. While many survey papers aim at summarizing the landscape of techniques for modelling system behavior and infering the root cause of a problem based in the resulting models, none of those focuses on analyzing how the different techniques in the literature fit growing requirements in terms of performance and scalability. In this survey, we provide a review of root-cause analysis, focusing on these particular aspects. We also provide guidance to choose the best root-cause analysis strategy depending on the requirements of a particular system and application.
AI – The Present in the Making
I attended the Huawei European Innovation Day recently, and was enthralled by how the new technology is giving rise to industrial revolutions. These revolutions are what will eventually unlock the development potential around the world. It is important to leverage the emerging technologies, since they are the resources which will lead us to innovation and progress. Huawei is innovative in its partnerships and collaboration to define the future, and the event was a huge success. For many people, the concept of Artificial Intelligence (AI) is a thing of the future. It is the technology that has yet to be introduced.
Location Dependent Dirichlet Processes
Sun, Shiliang, Paisley, John, Liu, Qiuyang
Dirichlet processes (DP) are widely applied in Bayesian nonparametric modeling. However, in their basic form they do not directly integrate dependency information among data arising from space and time. In this paper, we propose location dependent Dirichlet processes (LDDP) which incorporate nonparametric Gaussian processes in the DP modeling framework to model such dependencies. We develop the LDDP in the context of mixture modeling, and develop a mean field variational inference algorithm for this mixture model. The effectiveness of the proposed modeling framework is shown on an image segmentation task.
Top Machine Learning Interview Questions and Answers for 2017
According to a list released by the popular job portal Indeed.com on 30 fastest growing jobs in technology- With the demand for machine learning engineers and data scientists outstripping the supply, organizations are finding it difficult to hire skilled talent and so are prospective candidates for machine learning jobs finding it difficult to crack a machine learning interview. Machine learning is a broad field and there are no specific machine learning interview questions that are likely to be asked during a machine learning engineer job interview because the machine learning interview questions asked will focus on the open job position the employer is trying to fill. For instance, if you consider a machine learning engineer job role for finance vs. a robotics job, both of them will be completely different in terms of data, architecture and the responsibilities involved. Machine learning engineer job role for robotics will require a candidate to focus working on Neural Networks based architecture while the machine learning tasks for finance will focus working more on Linear and Logistic regression algorithms. A machine learning interview is definitely not a pop quiz and one must know what to expect going in.
WatsonPaths: Scenario-Based Question Answering and Inference over Unstructured Information
Lally, Adam (Information Technology and Services) | Bagchi, Sugato (IBM Research) | Barborak, Michael A. (IBM T. J. Watson Research Center) | Buchanan, David W. (IBM T. J. Watson Research Center) | Chu-Carroll, Jennifer (IBM Research) | Ferrucci, David A. (Bridgewater) | Glass, Michael R. (IBM Research) | Kalyanpur, Aditya (IBM T. J. Watson Research Center) | Mueller, Erik T. (Capital One) | Murdock, J. William (IBM T. J. Watson Research Center) | Patwardhan, Siddharth (IBM T. J. Watson Research Center) | Prager, John M. (IBM T. J. Watson Research Center)
We present WatsonPaths, a novel system that can answer scenario-based questions. These include medical questions that present a patient summary and ask for the most likely diagnosis or most appropriate treatment. WatsonPaths builds on the IBM Watson question answering system. WatsonPaths breaks down the input scenario into individual pieces of information, asks relevant subquestions of Watson to conclude new information, and represents these results in a graphical model. Probabilistic inference is performed over the graph to conclude the answer. On a set of medical test preparation questions, WatsonPaths shows a significant improvement in accuracy over multiple baselines.
AI – The Present in the Making
I attended the Huawei European Innovation Day recently, and was enthralled by how the new technology is giving rise to industrial revolutions. These revolutions are what will eventually unlock the development potential around the world. It is important to leverage the emerging technologies, since they are the resources which will lead us to innovation and progress. Huawei is innovative in its partnerships and collaboration to define the future, and the event was a huge success. For many people, the concept of Artificial Intelligence (AI) is a thing of the future. It is the technology that has yet to be introduced.
Probabilistic Active Learning of Functions in Structural Causal Models
Rubenstein, Paul K., Tolstikhin, Ilya, Hennig, Philipp, Schoelkopf, Bernhard
We consider the problem of learning the functions computing children from parents in a Structural Causal Model once the underlying causal graph has been identified. This is in some sense the second step after causal discovery. Taking a probabilistic approach to estimating these functions, we derive a natural myopic active learning scheme that identifies the intervention which is optimally informative about all of the unknown functions jointly, given previously observed data. We test the derived algorithms on simple examples, to demonstrate that they produce a structured exploration policy that significantly improves on unstructured base-lines.