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28th Conference on Uncertainty in Artificial Intelligence, UAI 2012

作者： Amizadeh, Saeed Thiesson, Bo Hauskrecht, Milos Intelligent Systems Program University of Pittsburgh Pittsburgh PA 15213 United States Microsoft Research Redmond WA 98052 United States Department of Computer Science University of Pittsburgh Pittsburgh PA 15213 United States

ISBN: (纸本)9780974903989

In recent years, non-parametric methods utilizing random walks on graphs have been used to solve a wide range of machine learning problems, but in their simplest form they do not scale well due to the quadratic complexity. In this paper, a new dual-tree based variational approach for approximating the transition matrix and efficiently performing the random walk is proposed. The approach exploits a connection between kernel density estimation, mixture modeling, and random walk on graphs in an optimization of the transition matrix for the data graph that ties together edge transitions probabilities that are similar. Compared to the de facto standard approximation method based on k-nearestneighbors, we demonstrate order of magnitudes speedup without sacrificing accuracy for Label Propagation tasks on benchmark data sets in semi-supervised learning.

关键词： Random processes

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Keyword annotation of biomedicai documents with graph-based similarity methods

Keyword annotation of biomedicai documents with graph-based ...

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IEEE International Conference on Bioinformatics and Biomedicine (BIBM)

作者： Shuguang Wang Milos Hauskrecht Intelligent Systems Program University of Pittsburgh Pittsburgh USA Department of Computer Science University of Pittsburgh Pittsburgh USA

In this paper, we present a new approach that lets us extract, and represent relations among terms (concepts) in the documents and uses these relations to support various document analysis applications. Our approach works by building a graph of local co-occurrence relations among terms that are extracted directly from text and by defining a global similarity metric among these terms and sets of terms using the graph and its connectivity. We demonstrate the benefit of the approach on the problem of MeSH keyword annotation of documents based on their abstracts.

关键词： Measurement Kernel Resistance Immune system Standards Search engines Abstracts

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The impact of social performance visualization on students

The impact of social performance visualization on students

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12th IEEE International Conference on Advanced Learning Technologies, ICALT 2012

作者： Falakmasir, Mohammad Hassan Hsiao, I.-Han Mazzola, Luca Grant, Nancy Brusilovsky, Peter Intelligent Systems Program University of Pittsburgh Pittsburgh PA United States School of Information Sciences University of Pittsburgh Pittsburgh PA United States Faculty of Communication Sciences University of Lugano Lugano Switzerland Department of Computer Information Science Community College of Allegheny County West Mifflin PA United States

ISBN: (纸本)9780769547022

Over the last 10 years two major research directions explored the benefits of visualizing student learning progress. One stream of research on learning performance visualization attempts to build a visual presentation of students' learning progress, targeting the needs of instructors and academic advisors. The other stream of research on Open Student Modeling (OSM) attempts to visualize the state of individual student's knowledge and present the visualization directly to the student. The results of the studies in that area show that, presenting students with basic representation of their knowledge will result in facilitating their metacognitive activities and promoting self-reflection and awareness. This paper tries to study the impact of a more sophisticated form of performance visualization on students. We believe that our visualization tool can positively influence students by granting them the opportunity to get a view of their performance in the content of the class progress. Moreover, we tried to boost their motivation by building a positive sense of competition using a representation of average class performance. In this paper we present study comparing two groups of students, one using the visualization and another without visualization. The results of the study shows that: 1) the students are likely to use the social visualization tool during the whole semester to monitor their progress in comparison with their peers;2) the visualization tool encourages students to use the learning materials in a more continuous manner during the whole semester and 3) students will achieve a higher success rate in answering self-assessment quizzes. © 2012 IEEE.

关键词： Students

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A multivariate probabilistic method for comparing two clinical datasets 12

A multivariate probabilistic method for comparing two clinic...

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2nd ACM SIGHIT International Health Informatics Symposium, IHI'12

作者： Sverchkov, Yuriy Visweswaran, Shyam Clermont, Gilles Hauskrecht, Milos Cooper, Gregory F. Intelligent Systems Program University of Pittsburgh Pittsburgh PA 15260 United States Department of Biomedical Informatics University of Pittsburgh Pittsburgh PA 15260 United States Department of Computer Science University of Pittsburgh Pittsburgh PA 15260 United States Department of Critical Care Medicine University of Pittsburgh Pittsburgh PA 15260 United States

ISBN: (纸本)9781450307819

We present a novel method for obtaining a concise and mathematically grounded description of multivariate differences between a pair of clinical datasets. Often data collected under similar circumstances reect fundamentally different patterns. For example, information about patients undergoing similar treatments in different intensive care units (ICUs), or within the same ICU during different periods, may show systematically different outcomes. In such circumstances, the multivariate probability distributions induced by the datasets would differ in selected ways. To capture the probabilistic relationships, we learn a Bayesian network (BN) from the union of the two datasets. We include an indicator variable that represents the dataset from which a given patient record is obtained. We then extract the relevant conditional distributions from the network by finding the conditional probabilities that differ most when condi- tioning on the indicator variable. Our work is a form of explanation that bears some similarity to previous work on BN explanation;however, while previous work has mostly focused on justifying inference, our work is aimed at explaining multivariate differences between distributions. Copyright © 2012 ACM.

关键词： Bayesian networks

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The Impact of Social Performance Visualization on Students

The Impact of Social Performance Visualization on Students

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International Conference on Advanced Learning Technologies (ICALT)

作者： Mohammad Hassan Falakmasir I-Han Hsiao Luca Mazzola Nancy Grant Peter Brusilovsky Intelligent Systems Program University of Pittsburgh Pittsburgh PA USA School of Information Sciences University of Pittsburgh Pittsburgh PA USA Faculty of Communication Sciences University of Lugano Lugano Switzerland Department of Computer Information Science Community College of Allegheny West Mifflin PA USA

Over the last 10 years two major research directions explored the benefits of visualizing student learning progress. One stream of research on learning performance visualization attempts to build a visual presentation of students' learning progress, targeting the needs of instructors and academic advisors. The other stream of research on Open Student Modeling (OSM) attempts to visualize the state of individual student's knowledge and present the visualization directly to the student. The results of the studies in that area show that, presenting students with basic representation of their knowledge will result in facilitating their metacognitive activities and promoting self-reflection and awareness. This paper tries to study the impact of a more sophisticated form of performance visualization on students. We believe that our visualization tool can positively influence students by granting them the opportunity to get a view of their performance in the content of the class progress. Moreover, we tried to boost their motivation by building a positive sense of competition using a representation of average class performance. In this paper we present study comparing two groups of students, one using the visualization and another without visualization. The results of the study shows that: 1) the students are likely to use the social visualization tool during the whole semester to monitor their progress in comparison with their peers; 2) the visualization tool encourages students to use the learning materials in a more continuous manner during the whole semester and 3) students will achieve a higher success rate in answering self-assessment quizzes.

关键词： Data visualization Adaptation models Educational institutions Visualization Artificial intelligence Communities

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An efficient framework for constructing generalized locally-induced text metrics

An efficient framework for constructing generalized locally-...

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22nd International Joint Conference on Artificial Intelligence, IJCAI 2011

作者： Amizadeh, Saeed Wang, Shuguang Hauskrecht, Milos Intelligent Systems Program University of Pittsburgh United States Department of Computer Science University of Pittsburgh United States

ISBN: (纸本)9781577355120

In this paper, we propose a new framework for constructing text metrics which can be used to compare and support inferences among terms and sets of terms. Our metric is derived from data-driven kernels on graphs that let us capture global relations among terms and sets of terms, regardless of their complexity and size. To compute the metric efficiently for any two subsets of terms, we develop an approximation technique that relies on the precompiled term-term similarities. To scale-up the approach to problems with huge number of terms, we develop and experiment with a solution that subsamples the term space. We demonstrate the benefits of the whole framework on two text inference tasks: prediction of terms in the article from its abstract and query expansion in information retrieval.

关键词： Abstracting

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Does query-based diagnostics work?

Does query-based diagnostics work?

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8th Bayesian Modeling ApplicationsWorkshop, BMAW 2011

作者： Ratnapinda, Parot Druzdzel, Marek J. Decision Systems Laboratory School of Information Sciences and Intelligent Systems Program University of Pittsburgh Pittsburgh PA 15260 United States Faculty of Computer Science Bialystok University of Technology Wiejska 45A 15-351 Bialystok Poland

Query-based diagnostics (Agosta, Gardos, & Druzdzel, 2008) offers passive, incremental construction of diagnostic models that rest on the interaction between a diagnostician and a computer-based diagnostic system. Effectively, this approach minimizes knowledge engineering, the main bottleneck in practical application of Bayesian networks. While this idea is appealing, it has undergone only limited testing in practice. We describe a series of experiments that subject a prototype implementing passive, incremental model construction to a rigorous practical test. We show that the prototype's diagnostic accuracy reaches reasonable levels after merely tens of cases and continues to increase with the number of cases, comparing favorably to state of the art approaches based on learning.

关键词： Bayesian networks

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Modeling dynamic systems with memory: What is the right time-order?

Modeling dynamic systems with memory: What is the right time...

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8th Bayesian Modeling ApplicationsWorkshop, BMAW 2011

作者： Lupínska-Dubicka, Anna Druzdzel, Marek J. Faculty of Computer Science Bialystok University of Technology Wiejska 45A 15-351 Bialystok Poland Decision Systems Laboratory School of Information Sciences and Intelligent Systems Program University of Pittsburgh Pittsburgh PA 15260 United States

Most practical uses of Dynamic Bayesian Networks (DBNs) involve temporal inuences of the first order, i.e., inuences between neighboring time steps. This choice is a convenient approximation inuenced by the existence of efficient algorithms for first order models and limitations of available tools. We focus on the question whether constructing higher time-order models is worth the effort when the underlying system's memory goes beyond the current state. We present the results of an experiment with a series of DBN models monitoring woman's monthly cycle. We show that higher order models are significantly more accurate. However, we have also observed overfitting and a resulting decrease in accuracy when the time order chosen is too high.

关键词： Bayesian networks

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A Radial Basis Function Spike Model for Indirect Learning via Integrate-and-Fire Sampling and Reconstruction Techniques

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Advances in Artificial Neural systems 2012年第1期2012卷

作者： X. Zhang G. Foderaro C. Henriquez A. M. J. VanDongen S. Ferrari Laboratory for Intelligent Systems and Control (LISC) Department of Mechanical Engineering and Materials Science Duke University Durham NC 27708 USAduke.edu Department of Biomedical Engineering and Department of Computer Science Duke University Durham NC 27708 USAduke.edu Program in Neuroscience & Behavioral Disorders Duke-NUS Graduate Medical School Singapore Singapore

This paper presents a deterministic and adaptive spike model derived from radial basis functions and a leaky integrate-and-fire sampler developed for training spiking neural networks without direct weight manipulation. Several algorithms have been proposed for training spiking neural networks through biologically-plausible learning mechanisms, such as spike-timing-dependent synaptic plasticity and Hebbian plasticity. These algorithms typically rely on the ability to update the synaptic strengths, or weights, directly, through a weight update rule in which the weight increment can be decided and implemented based on the training equations. However, in several potential applications of adaptive spiking neural networks, including neuroprosthetic devices and CMOS/memristor nanoscale neuromorphic chips, the weights cannot be manipulated directly and, instead, tend to change over time by virtue of the pre- and postsynaptic neural activity. This paper presents an indirect learning method that induces changes in the synaptic weights by modulating spike-timing-dependent plasticity by means of controlled input spike trains. In place of the weights, the algorithm manipulates the input spike trains used to stimulate the input neurons by determining a sequence of spike timings that minimize a desired objective function and, indirectly, induce the desired synaptic plasticity in the network.

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Improving phrase-based translation with prototypes of short phrases

Improving phrase-based translation with prototypes of short ...

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"2010 Human Language Technologies Conference ofthe North American Chapter of the Association for Computational Linguistics, NAACL HLT 2010"

作者： Liberato, Frank Mohit, Behrang Hwa, Rebecca Department of Computer Science University of Pittsburgh United States Intelligent Systems Program University of Pittsburgh United States

ISBN: (纸本)1932432655

We investigate methods of generating additional bilingual phrase pairs for a phrase-based decoder by translating short sequences of source text. Because our translation task is more constrained, we can use a model that employs more linguistically rich features than a traditional decoder. We have implemented an example of this approach. Experimental results suggest that the phrase pairs produced by our method are useful to the decoder, and lead to improved sentence translations. © 2010 Association for Computational Linguistics.

关键词： Decoding

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