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Search Results: 1 - 10 of 2989 matches for " Hossein Azari Soufiani "
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Graphlet decomposition of a weighted network
Hossein Azari Soufiani,Edoardo M Airoldi
Computer Science , 2012,
Abstract: We introduce the graphlet decomposition of a weighted network, which encodes a notion of social information based on social structure. We develop a scalable inference algorithm, which combines EM with Bron-Kerbosch in a novel fashion, for estimating the parameters of the model underlying graphlets using one network sample. We explore some theoretical properties of the graphlet decomposition, including computational complexity, redundancy and expected accuracy. We demonstrate graphlets on synthetic and real data. We analyze messaging patterns on Facebook and criminal associations in the 19th century.
A Statistical Decision-Theoretic Framework for Social Choice
Hossein Azari Soufiani,David C. Parkes,Lirong Xia
Computer Science , 2014,
Abstract: In this paper, we take a statistical decision-theoretic viewpoint on social choice, putting a focus on the decision to be made on behalf of a system of agents. In our framework, we are given a statistical ranking model, a decision space, and a loss function defined on (parameter, decision) pairs, and formulate social choice mechanisms as decision rules that minimize expected loss. This suggests a general framework for the design and analysis of new social choice mechanisms. We compare Bayesian estimators, which minimize Bayesian expected loss, for the Mallows model and the Condorcet model respectively, and the Kemeny rule. We consider various normative properties, in addition to computational complexity and asymptotic behavior. In particular, we show that the Bayesian estimator for the Condorcet model satisfies some desired properties such as anonymity, neutrality, and monotonicity, can be computed in polynomial time, and is asymptotically different from the other two rules when the data are generated from the Condorcet model for some ground truth parameter.
Random Utility Theory for Social Choice
Hossein Azari Soufiani,David C. Parkes,Lirong Xia
Computer Science , 2012,
Abstract: Random utility theory models an agent's preferences on alternatives by drawing a real-valued score on each alternative (typically independently) from a parameterized distribution, and then ranking the alternatives according to scores. A special case that has received significant attention is the Plackett-Luce model, for which fast inference methods for maximum likelihood estimators are available. This paper develops conditions on general random utility models that enable fast inference within a Bayesian framework through MC-EM, providing concave loglikelihood functions and bounded sets of global maxima solutions. Results on both real-world and simulated data provide support for the scalability of the approach and capability for model selection among general random utility models including Plackett-Luce.
Capturing Variation and Uncertainty in Human Judgment
Andrew Mao,Hossein Azari Soufiani,Yiling Chen,David C. Parkes
Computer Science , 2013,
Abstract: The well-studied problem of statistical rank aggregation has been applied to comparing sports teams, information retrieval, and most recently to data generated by human judgment. Such human-generated rankings may be substantially different from traditional statistical ranking data. In this work, we show that a recently proposed generalized random utility model reveals distinctive patterns in human judgment across three different domains, and provides a succinct representation of variance in both population preferences and imperfect perception. In contrast, we also show that classical statistical ranking models fail to capture important features from human-generated input. Our work motivates the use of more flexible ranking models for representing and describing the collective preferences or decision-making of human participants.
Preference Elicitation For General Random Utility Models
Hossein Azari Soufiani,David C. Parkes,Lirong Xia
Computer Science , 2013,
Abstract: This paper discusses {General Random Utility Models (GRUMs)}. These are a class of parametric models that generate partial ranks over alternatives given attributes of agents and alternatives. We propose two preference elicitation scheme for GRUMs developed from principles in Bayesian experimental design, one for social choice and the other for personalized choice. We couple this with a general Monte-Carlo-Expectation-Maximization (MC-EM) based algorithm for MAP inference under GRUMs. We also prove uni-modality of the likelihood functions for a class of GRUMs. We examine the performance of various criteria by experimental studies, which show that the proposed elicitation scheme increases the precision of estimation.
Stereo 3D Mouse Cursor: A Method for Interaction with 3D Objects in a Stereoscopic Virtual 3D Space
Hossein Azari,Irene Cheng,Anup Basu
International Journal of Digital Multimedia Broadcasting , 2010, DOI: 10.1155/2010/419493
Abstract: We introduce a different approach of applying stereoscopy principles to implement a virtual 3D pointing technique called stereo 3D mouse cursor (S3D-Cursor) based on two or more views of an ordinary mouse cursor. The basics of such an idea have already been applied as a by-product of some stereo-based visualization applications with usually less attention to its strengths or weaknesses as a generic alternative of its 2D counterpart in stereoscopic 3D space. Here, we examine if such an idea satisfies all or the main expected requirements of an abstract 3D cursor. Moreover, we analyze its accuracy and evaluate the applicability of this approach in terms of different efficiency factors. For this purpose, we have adapted a real-time point-based rendering software called QSplat to a multiview rendering version named QSplatMV. We have implemented the S3D-Cursor on top of this new application and developed a simple editing toolset for manipulating the virtual 3D objects. Our user evaluation results suggest the effectiveness of the approach in terms of detection accuracy and user satisfaction compared to using an ordinary mouse cursor on a conventional 2D screen. 1. Introduction The stereopsis capability of the human vision is one of the primary means used by our vision system to give us a 3D perception of the world [1]. This ability allows us to have a sense of the 3rd dimension from the two slightly different images of the world projected onto our eyes retina. Benefiting from this intrinsic ability, a wide variety of different stereoscopic devices and techniques are employed to create the illusion of depth from the visual stereo contents. Recent advances in these technologies enable the users to watch contents in 3D without using any filtering glasses (multiview autostereoscopic 3D displays [2]) or watch 3D contents in full-colour on conventional displays (colour code glasses [3]). Along with these advances in stereoscopic display technologies it is also necessary to evolve the current 2D/3D interaction techniques and devices for interplay with these new attractive virtual 3D environments. Among these, pointing to the targets (objects or other GUI components) using some devices such as mouse is probably the most appealing interaction method especially useful to work within the graphics environments [4]. For this reason, providing the possibility of pointing to any arbitrary voxel of the 3D space is one of the first expectations of any user who wants to migrate from 2D to 3D space applications. In this regard, several 3D pointing techniques (or in broader
Diagnosis of a Lingual Mandibular Bone Defect (Stafne’s Bone Defect) by CT Scan
S. Nikzad,A. Azari,F. Hossein Khezri
Iranian Journal of Radiology , 2010,
Abstract: The lingual mandibular bone defect, which is also known as Stafne's bone defect, is a rare entity commonly affecting the posterior lingual part of the mandible. Although this lesion usually contains normal connective tissue compartments, it may be misinterpreted as tumor like lesions. In this manuscript, based on the density analysis of the CT images and through use of a simplified quantification system, a novel approach has been introduced which attempts to differentiate the benign nature of the defect
Variational Iteration Method for Image Restoration
Keyvan Yahya,Jafar Biazar,Hossein Azari,Pouyan Rafiei Fard
Mathematics , 2010,
Abstract: The famous Perona-Malik (P-M) equation which was at first introduced for image restoration has been solved via various numerical methods. In this paper we will solve it for the first time via applying a new numerical method called the Variational Iteration Method (VIM) and the correspondent approximated solutions will be obtained for the P-M equation with regards to relevant error analysis. Through implementation of our algorithm we will access some effective results which are deserved to be considered as worthy as the other solutions issued by the other methods.
Homotopy Perturbation Method for Image Restoration and Denoising
Keyvan Yahya,Jafar Biazar,Hossein Azari,Pouyan Rafiei Fard
Mathematics , 2010,
Abstract: The famous Perona-Malik (P-M) equation which was at first introduced for image restoration has been solved via various numerical methods. In this paper we will solve it for the first time via applying a new numerical method called Homotopy Perturbation Method (HMP) and the correspondent approximated solutions will be obtained for the P-M equation with regards to relevant error analysis. Through implementation of our algorithm we will access some effective results which are deserved to be considered as worthy as the other solutions issued by the other methods.
A review of recent method for surface preparation of metal in resin- bonded bridges.Part II: Biomcchamica! and technical considerations
Azari A.
Journal of Dental Medicine , 1999,
Abstract: After approximately 40 years of experience in the field of resin - bonded restorations (R.B.R),"nthese restorations arc one of the most controversial. During these years, many suggestions have been"nmade for better performance and increasing durability of these restorations. The aims of this paper are:"n1 - Reviewing the literature for the so many factors involving the success or failure of R.B.R."n2 - Introducing a new and simplified method for increasing the durability and /or relention of R.B.R.
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