Personalization is a ubiquitous phenomenon in our daily online experience. While such technology is critical for helping us combat the overload of information we face, in many cases, we may not even realize that our results are being tailored to our personal tastes and preferences. Worse yet, when such a system makes a mistake, we have little recourse to correct it.

Our work aims at building probabilistic tools for constructing and maintaining large-scale knowledge bases containing entity-relationship-entity triples (statements) extracted from the Web. In order to mitigate the uncertainty inherent in information extraction and integration we propose leveraging the "wisdom of the crowds" by aggregating truth assessments that users provide about statements. The suggested method, CoBayes, operates on a collection of statements, a set of deduction rules (e.g. transitivity), a set of users, and a set of truth assessments of users about statements. We propose a joint probabilistic model of the truth values of statements and the expertise of users for assessing statements. The truth values of statements are interconnected through derivations based on the deduction rules. The correctness of a user's assessment for a given statement is modeled by linear mappings from user descriptions and statement descriptions into a common latent knowledge space where the inner product between user and statement vectors determines the probability that the user assessment for that statement will be correct. Bayesian inference in this complex graphical model is performed using mixed variational and expectation propagation message passing. We demonstrate the viability of CoBayes in comparison to other approaches, on realworld datasets and user feedback collected from Amazon Mechanical Turk.

Traffic classification using machine learning continues to be an active research area. The majority of work in this area uses off-the-shelf machine learning tools and treats them as black-box classifiers. This approach turns all the modelling complexity into a feature selection problem. In this paper, we build a problem-specific solution to the traffic classification problem by designing a custom probabilistic graphical model. Graphical models are a modular framework to design classifiers which incorporate domain-specific knowledge. More specifically, our solution introduces semi-supervised learning which means we learn from both labelled and unlabelled traffic flows. We show that our solution performs competitively compared to previous approaches while using less data and simpler features. Copyright © 2010 ACM.

The infinite hidden Markov model is a non-parametric extension of the widely used hidden Markov model. Our paper introduces a new inference algorithm for the infinite Hidden Markov model called beam sampling. Beam sampling combines slice sampling, which limits the number of states considered at each time step to a finite number, with dynamic programming, which samples whole state trajectories efficiently. Our algorithm typically outperforms the Gibbs sampler and is more robust. We present applications of iHMM inference using the beam sampler on changepoint detection and text prediction problems.

We introduces a new probability distribution over a potentially infinite number of binary Markov chains which we call the Markov Indian buffet process. This process extends the IBP to allow temporal dependencies in the hidden variables. We use this stochastic process to build a nonparametric extension of the factorial hidden Markov model. After working out an inference scheme which combines slice sampling and dynamic programming we demonstrate how the infinite factorial hidden Markov model can be used for blind source separation.