403 research outputs found

    When is Enough Good Enough in Gravitational Wave Source Modeling?

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    A typical approach to developing an analysis algorithm for analyzing gravitational wave data is to assume a particular waveform and use its characteristics to formulate a detection criteria. Once a detection has been made, the algorithm uses those same characteristics to tease out parameter estimates from a given data set. While an obvious starting point, such an approach is initiated by assuming a single, correct model for the waveform regardless of the signal strength, observation length, noise, etc. This paper introduces the method of Bayesian model selection as a way to select the most plausible waveform model from a set of models given the data and prior information. The discussion is done in the scientific context for the proposed Laser Interferometer Space Antenna.Comment: 7 pages, 2 figures, proceedings paper for the Sixth International LISA Symposiu

    Consistent Estimation of Mixed Memberships with Successive Projections

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    This paper considers the parameter estimation problem in Mixed Membership Stochastic Block Model (MMSB), which is a quite general instance of random graph model allowing for overlapping community structure. We present the new algorithm successive projection overlapping clustering (SPOC) which combines the ideas of spectral clustering and geometric approach for separable non-negative matrix factorization. The proposed algorithm is provably consistent under MMSB with general conditions on the parameters of the model. SPOC is also shown to perform well experimentally in comparison to other algorithms

    Information-based objective functions for active data selection

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    Learning can be made more efficient if we can actively select particularly salient data points. Within a Bayesian learning framework, objective functions are discussed that measure the expected informativeness of candidate measurements. Three alternative specifications of what we want to gain information about lead to three different criteria for data selection. All these criteria depend on the assumption that the hypothesis space is correct, which may prove to be their main weakness

    A Spectral Algorithm with Additive Clustering for the Recovery of Overlapping Communities in Networks

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    This paper presents a novel spectral algorithm with additive clustering designed to identify overlapping communities in networks. The algorithm is based on geometric properties of the spectrum of the expected adjacency matrix in a random graph model that we call stochastic blockmodel with overlap (SBMO). An adaptive version of the algorithm, that does not require the knowledge of the number of hidden communities, is proved to be consistent under the SBMO when the degrees in the graph are (slightly more than) logarithmic. The algorithm is shown to perform well on simulated data and on real-world graphs with known overlapping communities.Comment: Journal of Theoretical Computer Science (TCS), Elsevier, A Para\^itr

    Learning in Parallel

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    In this paper, we extend Valiant's sequential model of concept learning from examples [Valiant 1984] and introduce models for the e cient learning of concept classes from examples in parallel. We say that a concept class is NC-learnable if it can be learned in polylog time with a polynomial number of processors. We show that several concept classes which are polynomial-time learnable are NC-learnable in constant time. Some other classes can be shown to be NC-learnable in logarithmic time, but not in constant time. Our main result shows that other classes, such as s-fold unions of geometrical objects in Euclidean space, which are polynomial-time learnable by a greedy set cover technique, are NC-learnable using a non-greedy technique. We also show that (unless P RNC) several polynomial-time learnable concept classes related to linear programming are not NC-learnable. Equivalence of various parallel learning models and issues of fault-tolerance are also discussed
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