76,368 research outputs found

    A review on probabilistic graphical models in evolutionary computation

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    Thanks to their inherent properties, probabilistic graphical models are one of the prime candidates for machine learning and decision making tasks especially in uncertain domains. Their capabilities, like representation, inference and learning, if used effectively, can greatly help to build intelligent systems that are able to act accordingly in different problem domains. Evolutionary algorithms is one such discipline that has employed probabilistic graphical models to improve the search for optimal solutions in complex problems. This paper shows how probabilistic graphical models have been used in evolutionary algorithms to improve their performance in solving complex problems. Specifically, we give a survey of probabilistic model building-based evolutionary algorithms, called estimation of distribution algorithms, and compare different methods for probabilistic modeling in these algorithms

    Recent advances in imprecise-probabilistic graphical models

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    We summarise and provide pointers to recent advances in inference and identification for specific types of probabilistic graphical models using imprecise probabilities. Robust inferences can be made in so-called credal networks when the local models attached to their nodes are imprecisely specified as conditional lower previsions, by using exact algorithms whose complexity is comparable to that for the precise-probabilistic counterparts

    Probabilistic Graphical Models and Algorithms for

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    In this thesis I present research in two fields: machine learning and computational biology. First, I develop new machine learning methods for graphical models that can be applied to protein problems. Then I apply graphical model algorithms to protein problems, obtaining improvements in protein structure prediction and protein structure alignment. First,in the machine learning work, I focus on a special kind of graphical model---conditional random fields (CRFs). Here, I present a new semi-supervised training procedure for CRFs that can be used to train sequence segmentors and labellers from a combination of labeled and unlabeled training data. Such learning algorithms can be applied to protein and gene name entity recognition problems. This work provides one of the first semi-supervised discriminative training methods for structured classification. Second, in my computational biology work, I focus mainly on protein problems. In particular, I first propose a tree decomposition method for solving the protein structure prediction and protein structure alignment problems. In so doing, I reveal why tree decomposition is a good method for many protein problems. Then, I propose a computational framework for detection of similar structures of a target protein with sparse NMR data, which can help to predict protein structure using experimental data. Finally, I propose a new machine learning approach---LS_Boost---to solve the protein fold recognition problem, which is one of the key steps in protein structure prediction. After a thorough comparison, the algorithm is proved to be both more accurate and more efficient than traditional z-Score method and other machine learning methods

    The Libra Toolkit for Probabilistic Models

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    The Libra Toolkit is a collection of algorithms for learning and inference with discrete probabilistic models, including Bayesian networks, Markov networks, dependency networks, and sum-product networks. Compared to other toolkits, Libra places a greater emphasis on learning the structure of tractable models in which exact inference is efficient. It also includes a variety of algorithms for learning graphical models in which inference is potentially intractable, and for performing exact and approximate inference. Libra is released under a 2-clause BSD license to encourage broad use in academia and industry
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