We study the seamless integration of community discovery and behavioral role analysis, in the domain of networks with node attributes. In particular, we focus on unifying the two tasks, by explicitly harnessing node a...
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ISBN:
(纸本)9781956792003
We study the seamless integration of community discovery and behavioral role analysis, in the domain of networks with node attributes. In particular, we focus on unifying the two tasks, by explicitly harnessing node attributes and behavioral role patterns in a principled manner. To this end, we propose two Bayesian probabilistic generative models of networks, whose novelty consists in the interrelationship of overlapping communities, roles, their behavioral patterns and node attributes. The devised models allow for a variety of exploratory, descriptive and predictive tasks. These are carried out through mean-field variational inference, which is in turn mathematically derived and implemented into a coordinate-ascent algorithm. A wide spectrum of experiments is designed, to validate the devised models against three classes of state-of-the-art competitors using various real-world benchmark data sets from different social networking services.
We present a probabilisticgraphical model that finds a sequence of optimal categories for a sequence of input symbols. Based on this mode, three algorithms are developed for identifying semantic patterns in texts. Th...
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ISBN:
(纸本)9780769544922
We present a probabilisticgraphical model that finds a sequence of optimal categories for a sequence of input symbols. Based on this mode, three algorithms are developed for identifying semantic patterns in texts. They are the algorithm for extracting semantic arguments of a verb, the algorithm for classifying the sense of an ambiguous word, and the algorithm for identifying noun phrases from a sentence. Experiments conducted on standard data sets show good results. For example, our method achieves an average precision of 92.96% and an average recall of 94.94% for extracting semantic argument boundaries of verbs on WSJ data from Penn Treebank and PropBank;an average accuracy of 81.12% for recognizing the six sense word 'line';and an average precision of 97.7% and an average recall of 98.8% for recognizing noun phrases on WSJ data from Penn Treebank.
In this work, we present an approach for performing computational storytelling in open domain based on Author Goals. Author Goals are constraints placed on a story event directed by the author of the system. There are...
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ISBN:
(纸本)9781450372176
In this work, we present an approach for performing computational storytelling in open domain based on Author Goals. Author Goals are constraints placed on a story event directed by the author of the system. There are two challenges present in this type of story generation: (1) automatically acquiring a model of story progression, and (2) guiding the progress of story progression in light of different goals. We propose a novel approach to story generation based on probabilisticgraphicalmodels and Loopy Belief Propagation (LBP) that addresses both of these problems. We show the applicability of our technique through a case study on the Visual Storytelling (VIST) 2017 dataset. We use image descriptions as author goals. This empirical analysis suggests that our approach is able to utilize goals information to better automatically generate stories.
probabilistic circuits (PCs) represent a probability distribution as a computational graph. Enforcing structural properties on these graphs guarantees that several inference scenarios become tractable. Among these pro...
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probabilistic circuits (PCs) represent a probability distribution as a computational graph. Enforcing structural properties on these graphs guarantees that several inference scenarios become tractable. Among these properties, structured decomposability is a particularly appealing one: it enables the efficient and exact computations of the probability of complex logical formulas, and can be used to reason about the expected output of certain predictive models under missing data. This paper proposes Strudel, a simple, fast and accurate learning algorithm for structured-decomposable PCs. Compared to prior work for learning structured-decomposable PCs, Strudel delivers more accurate single PC models in fewer iterations, and dramatically scales learning when building ensembles of PCs. It achieves this scalability by exploiting another structural property of PCs, called determinism, and by sharing the same computational graph across mixture components. We showthese advantages on standard density estimation benchmarks and challenging inference scenarios.
This paper introduces hybrid random fields, which are a class of probabilisticgraphicalmodels aimed at allowing for efficient Structure learning in high-dimensional domains. Hybrid random fields, along with the lear...
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This paper introduces hybrid random fields, which are a class of probabilisticgraphicalmodels aimed at allowing for efficient Structure learning in high-dimensional domains. Hybrid random fields, along with the learning algorithm we develop for them, are especially useful as a pseudo-likelihood estimation technique (rather than a technique for estimating strict joint probability distributions). In order to assess the generality of the proposed model, we prove that the class of pseudo-likelihood distributions representable by hybrid random fields Strictly includes the class of joint probability distributions representable by Bayesian networks. Once we establish this result, we develop a scalable algorithm for learning the Structure of hybrid random fields, which we call 'Markov Blanket Merging'. On the one hand, we characterize some complexity properties of Markov Blanket Merging both from a theoretical and from the experimental point of view, using a series of synthetic benchmarks. On the other hand. we evaluate the accuracy of hybrid random fields (as learned via Markov Blanket Merging) by comparing them to various alternative statistical models in a number of pattern classification and link-prediction applications. As the results show, learning hybrid random fields by the Markov Blanket Merging algorithm not only reduces significantly the computational Cost of structure learning with respect to several considered alternatives, but it also leads to models that are highly accurate as compared to the alternative ones. (C) 2009 Elsevier Ltd. All rights reserved.
graphical event models (GEMs) provide a framework for graphical representation of multivariate point processes. We propose a class of GEMs named Hawkesian graphical event models (HGEMs) for representing temporal depen...
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graphical event models (GEMs) provide a framework for graphical representation of multivariate point processes. We propose a class of GEMs named Hawkesian graphical event models (HGEMs) for representing temporal dependencies among different types of events from either a single event stream or multiple independent streams. In our proposed model, the intensity function for an event label is a linear combination of time-shifted kernels where time shifts correspond to prior occurrences of causal event labels in the history, as in a Hawkes process. The number of parameters in our model scales linearly in the number of edges in the graphical model, enabling efficient estimation and inference. This is in contrast to many existing GEMs where the number of parameters scales exponentially in the edges. We use two types of kernels: exponential and Gaussian kernels, and propose a two-step algorithm that combines strengths of both kernels and learns the structure for the underlying graphical model. Experiments on both synthetic and real-world data demonstrate the efficacy of the proposed HGEM, and exhibit expressive power of the two-step learning algorithm in characterizing self-exciting event patterns and reflecting intrinsic Granger-causal relationships.
A document image matching approach making use of probabilisticgraphicalmodels is proposed. The document image is first represented by a tree with the nodes in the tree corresponding to the regions in the image and t...
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ISBN:
(纸本)9784990644109;9781467322164
A document image matching approach making use of probabilisticgraphicalmodels is proposed. The document image is first represented by a tree with the nodes in the tree corresponding to the regions in the image and the edges indicating the parent-child relationships between them, transforming the problem to tree matching. A graphical model, i.e. pairwise Markov Random Field is defined on the tree, in which sense the nodes are considered as random variables and the edges encode the relations among these variables in the probability domain. The tree matching problem is then formulated as Maximum a Posterior (MAP) inference over the graphical model and solved by belief propagation. Since the underlying graphical model is tree-structured, the exact inference can be obtained. With properly defined potential functions in the joint probability represented by the graphical model, the disparity in tree representations caused by different image capturing conditions can be tolerated as demonstrated in the encouraging experimental results.
OpenMarkov is a Java open-source tool for building and evaluating probabilisticgraphicalmodels, including Bayesian networks, influence diagrams, and some Markov models. With more than 100,000 lines of code, it offer...
ISBN:
(纸本)9780999241141
OpenMarkov is a Java open-source tool for building and evaluating probabilisticgraphicalmodels, including Bayesian networks, influence diagrams, and some Markov models. With more than 100,000 lines of code, it offers some features for interactive learning, explanation of reasoning, and cost-effectiveness analysis that are not available in any other tool. OpenMarkov has been used in universities, research centers, and large companies in more than 30 countries on four continents. Several models, some of them for real-world medical applications, built with OpenMarkov, are publicly available on Internet.
We derive a multinomial sampling model for analyzing the relationships between two or more entities, The parameters in the multinomial model are derived from factorizing multi-way contingency tables. We show how conte...
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ISBN:
(纸本)9789898425799
We derive a multinomial sampling model for analyzing the relationships between two or more entities, The parameters in the multinomial model are derived from factorizing multi-way contingency tables. We show how contextual information can be included and propose a graphical representation of model dependencies. The graphical representation allows us to decompose a multivariate domain into interactions involving only a small number of variables. The approach formulates a probabilistic generative model for a single relation. By construction, the approach can easily deal with missing relations. We apply our approach to a social network domain where we predict the event that a user watches a movie. Our approach permits the integration of both information about the last movie watched by a user and a general temporal preference for a movie.
Ontologies and probabilisticgraphicalmodels are considered within the most efficient frameworks in knowledge representation. Ontologies are the key concept in semantic technology whose use is increasingly prevalent ...
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ISBN:
(纸本)9789898425805
Ontologies and probabilisticgraphicalmodels are considered within the most efficient frameworks in knowledge representation. Ontologies are the key concept in semantic technology whose use is increasingly prevalent by the computer science community. They provide a structured representation of knowledge characterized by its semantic richness. probabilisticgraphicalmodels (PGMs) are powerful tools for representing and reasoning under uncertainty. Nevertheless, both suffer from their building phase. It is well known that learning the structure of a PGM and automatic ontology enrichment are very hard problems. Therefore, several algorithms have been proposed for learning the PGMs structure from data and several others have led to automate the process of ontologies enrichment. However, there was not a real collaboration between these two research directions. In this work, we propose a two-way approach that allows PGMs and ontologies cooperation. More precisely, we propose to harness ontologies representation capabilities in order to enrich the building process of PGMs. We are in particular interested in object oriented Bayesian networks (OOBNs) which are an extension of standard Bayesian networks (BNs) using the object paradigm. We first generate a prior OOBN by morphing an ontology related to the problem under study and then, we describe how the learning process carried out with the OOBN might be a potential solution to enrich the ontology used initially.
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