Directed Networks
Transforming variables to central normality
Raymaekers, Jakob, Rousseeuw, Peter J.
Many real data sets contain features (variables) whose distribution is far from normal (gaussian). Instead, their distribution is often skewed. In order to handle such data it is customary to preprocess the variables to make them more normal. The Box-Cox and Yeo-Johnson transformations are well-known tools for this. However, the standard maximum likelihood estimator of their transformation parameter is highly sensitive to outliers, and will often try to move outliers inward at the expense of the normality of the central part of the data. We propose an automatic preprocessing technique that is robust against such outliers, which transforms the data to central normality. It compares favorably to existing techniques in an extensive simulation study and on real data.
Generalized Bayesian Posterior Expectation Distillation for Deep Neural Networks
Vadera, Meet P., Jalaian, Brian, Marlin, Benjamin M.
Monte Carlo methods provide one solution to represent neural network parameter posteriors as ensembles of networks, but this requires In this paper, we present a general framework large amounts of both storage and compute time (Neal, for distilling expectations with respect to the 1996; Welling and Teh, 2011). Bayesian posterior distribution of a deep neural network classifier, extending prior work on To help overcome these problems, Balan et al. (2015) introduced the Bayesian Dark Knowledge framework. The a model training method referred to as Bayesian proposed framework takes as input "teacher" Dark Knowledge (BDK). BDK attempts to compress (or and student model architectures and a general distill) the Bayesian posterior predictive distribution induced posterior expectation of interest. The distillation by the full parameter posterior of a "teacher" network method performs an online compression (represented via a set of Mote Carlo samples) into a of the selected posterior expectation using iteratively significantly more compact "student" network. The major generated Monte Carlo samples. We advantage of BDK is that the computational complexity focus on the posterior predictive distribution of prediction at test time is drastically reduced compared and expected entropy as distillation targets. We to directly computing predictions via Monte Carlo averages investigate several aspects of this framework over the set of teacher network samples (the teacher including the impact of uncertainty and the ensemble).
Conformal Prediction: a Unified Review of Theory and New Challenges
Zeni, Gianluca, Fontana, Matteo, Vantini, Simone
In this work we provide a review of basic ideas and novel developments about Conformal Prediction -- an innovative distribution-free, non-parametric forecasting method, based on minimal assumptions -- that is able to yield in a very straightforward way predictions sets that are valid in a statistical sense also in in the finite sample case. The in-depth discussion provided in the paper covers the theoretical underpinnings of Conformal Prediction, and then proceeds to list the more advanced developments and adaptations of the original idea.
MCMC-Based Learning of Finite Bivariate Beta Mixture Models
Rasti, Maryam (Concordia University ) | Manouchehri, Narges (Concordia University) | Bouguila, Nizar (Concordia University)
In this paper, we present a Bayesian approach for finite mixture models based on three-parameter bivariate Beta distributions. The estimation of the parameters is based on the Monte Carlo simulation technique of Gibbs sampling mixed with a Metropolis-Hastings step. The performance of our Bayesian algorithm is verified by several synthetic datasets and in the end, the feasibility of the proposed method is demonstrated by experimenting on some real datasets in which, the results are compared with those obtained by implementing the same approach using Gaussian mixture model.
Constaint-Based Learning for Non-Parametric Continuous Bayesian Networks
Lasserre, Marvin (Laboratoire d'Informatique de Paris 6 ) | Lebrun, Rรฉgis (Airbus AI Research) | Wuillemin, Pierre-Henri (Laboratoire d'Informatique de Paris 6)
Modeling high-dimensional multivariate distributions is a computationally challenging task. Bayesian networks have been successfully used to reduce the complexity and simplify the problem with discrete variables. However, it lacks of a general model for continuous variables. In order to overcome this problem, Elidan (2010) proposed the model of copula bayesian networks (CBN) that reparametrizes bayesian networks with conditional copula functions. We propose a new learning algorithm for CBN based on a PC algorithm and a conditional independence test proposed by Bouezmarni, Rombouts, Taamouti (2009). This test being non-parametric, no model assumptions are made allowing it to be as general as possible. This algorithm is compared on generated data with the score based method proposed by Elidan (2010)}. Not only it proves to be faster, but also it generalizes well on data generated from distributions far from the gaussian model.
Learning NAT-Modeled Bayesian Networks from Data
Xiang, Yang (University of Guelph ) | Wang, Qian (University of Guelph)
Bayesian networks (BNs) encode conditional independence to avoid combinatorial explosion on the number of variables, but are subject to exponential growth of space and inference time on the number of causes per effect variable. Among space-efficient local models, we focus on the Non-Impeding Noisy-AND Tree (NIN-AND Tree or NAT) models due to their multiple merits, and on NAT-modeled BNs where each multi-parent variable family may be encoded as a NAT-model. Although BN inference is generally exponential on treewidth, inference is tractable with NAT-modeled BNs of high treewidth and low density. In this work, we present the first study to learn NAT-modeled BNs from data. We apply the MDL principle to learning NAT-modeled BNs by developing a corresponding scoring function, and we couple it with heuristic structure search. We show that when data satisfy NAT causal independence, and high treewidth, low density structure, learning underlying NAT modeled BNs is feasible.
Stopping criterion for active learning based on deterministic generalization bounds
Ishibashi, Hideaki, Hino, Hideitsu
Active learning is a framework in which the learning machine can select the samples to be used for training. This technique is promising, particularly when the cost of data acquisition and labeling is high. In active learning, determining the timing at which learning should be stopped is a critical issue. In this study, we propose a criterion for automatically stopping active learning. The proposed stopping criterion is based on the difference in the expected generalization errors and hypothesis testing. We derive a novel upper bound for the difference in expected generalization errors before and after obtaining a new training datum based on PAC-Bayesian theory. Unlike ordinary PAC-Bayesian bounds, though, the proposed bound is deterministic; hence, there is no uncontrollable trade-off between the confidence and tightness of the inequality. We combine the upper bound with a statistical test to derive a stopping criterion for active learning. We demonstrate the effectiveness of the proposed method via experiments with both artificial and real datasets.
Linear Discriminant Analysis for Dimensionality Reduction in Python
Reducing the number of input variables for a predictive model is referred to as dimensionality reduction. Fewer input variables can result in a simpler predictive model that may have better performance when making predictions on new data. Linear Discriminant Analysis, or LDA for short, is a predictive modeling algorithm for multi-class classification. It can also be used as a dimensionality reduction technique, providing a projection of a training dataset that best separates the examples by their assigned class. The ability to use Linear Discriminant Analysis for dimensionality reduction often surprises most practitioners.
Cognitive Amplifier for Internet of Things
Huang, Bing, Bouguettaya, Athman, Neiat, Azadeh Ghari
With the emergence of IoT, there is a rising interest in applying Internet of Things (IoT) technology in the smart homes for making occupants' life more convenient. The convenience is underpinned by the principle of the least effort, i.e. the premise that humans would usually want to achieve goals with the least cognitive and physical efforts [2]. IoT refers to the networked interconnection of everyday things, which are augmented with capabilities such as sensing, actuating, and communication [21]. The availability of IoT devices including switch sensors, infrared motion sensors, pressure sensor, wearable sensors, accelerators, temperature, humidity, and light sensors have the potential to realize the convenience. It is a challenge that IoT devices are highly diverse in supporting infrastructure such as different programming language and communication protocols [5].
Enabling Edge Cloud Intelligence for Activity Learning in Smart Home
Huang, Bing, Bouguettaya, Athman, Dong, Hai
We propose a novel activity learning framework based on Edge Cloud architecture for the purpose of recognizing and predicting human activities. Although activity recognition has been vastly studied by many researchers, the temporal features that constitute an activity, which can provide useful insights for activity models, have not been exploited to their full potentials by mining algorithms. In this paper, we utilize temporal features for activity recognition and prediction in a single smart home setting. We discover activity patterns and temporal relations such as the order of activities from real data to develop a prompting system. Analysis of real data collected from smart homes was used to validate the proposed method.