Computer Science and Artificial Intelligence Lab (CSAIL): Recent submissions
Now showing items 941-960 of 2625
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Construction by robot swarms using extended stigmergy
(2005-04-08)We describe a system in which simple, identical, autonomous robots assemble two-dimensional structures out of identical building blocks. We show that, in a system divided in this way into mobile units and structural units, ...
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Motion Coordination Using Virtual Nodes
(2005-04-06)We describe how a virtual node abstraction layer can be used to coordinate the motion of real mobile nodes in a region of 2-space. In particular, we consider how nodes in a mobile ad hoc network can arrange themselves along ...
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On Relational Analysis of Algebraic Datatypes
(2005-04-05)We present a technique that enables the use of finite modelfinding to check the satisfiability of certain formulaswhose intended models are infinite. Such formulas arisewhen using the language of sets and relations to ...
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Wait-free Regular Storage from Byzantine Components
(2005-04-05)We present a simple, efficient, and self-contained construction of a wait-free regular register from Byzantine storage components. Our construction utilizes a novel building block, called 1-regular register, which can be ...
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An Expectation Maximization Approach for Integrated Registration, Segmentation, and Intensity Correction
(2005-04-01)This paper presents a statistical framework which combines the registration of an atlas with the segmentation of MR images. We use an Expectation Maximization-based algorithm to find a solution within the model, which ...
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Combining Variable Selection with Dimensionality Reduction
(2005-03-30)This paper bridges the gap between variable selection methods (e.g., Pearson coefficients, KS test) and dimensionality reductionalgorithms (e.g., PCA, LDA). Variable selection algorithms encounter difficulties dealing with ...
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Matrix Approximation and Projective Clustering via Iterative Sampling
(2005-03-29)We present two new results for the problem of approximating a given real m by n matrix A by a rank-k matrix D, where k < min{m, n}, so as to minimize ||A-D||_F^2. It is known that bysampling O(k/eps) rows of the matrix, ...
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Combining Object and Feature Dynamics in Probabilistic Tracking
(2005-03-02)Objects can exhibit different dynamics at different scales, a property that isoftenexploited by visual tracking algorithms. A local dynamicmodel is typically used to extract image features that are then used as inputsto a ...
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Receptive field structures for recognition
(2005-03-01)Localized operators, like Gabor wavelets and difference-of-Gaussian filters, are considered to be useful tools for image representation. This is due to their ability to form a  sparse code that can serve as a basis set ...
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File Synchronization with Vector Time Pairs
(2005-02-28)Vector time pairs are a new method for trackingsynchronization metadata. A vector time pairconsists of two vector times: one tracking filemodification history and one tracking filesynchronization history. Because the ...
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Impossibility of boosting distributed service resilience
(2005-02-25)We prove two theorems saying that no distributed system in whichprocesses coordinate using reliable registers and f-resilient servicescan solve the consensus problem in the presence of f+1 undetectableprocess stopping ...
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Discovering object categories in image collections
(2005-02-25)Given a set of images containing multiple object categories,we seek to discover those categories and their image locations withoutsupervision. We achieve this using generative modelsfrom the statistical text literature: ...
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Improving 802.11 Range with Forward Error Correction
(2005-02-24)The ISO/IEC 8802-11:1999(E) specification uses a 32-bit CRC for error detection and whole-packet retransmissions for recovery. In long-distance orhigh-interference links where the probability of a bit error is high,this ...
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Complexity of finding Nash equilibria in 0-1 bimatrix games
(2005-02-08)We exhibit a polynomial reduction from the problem of finding a Nashequilibrium of a bimatrix game with rational coefficients to the problemof finding a Nash equilibrium of a bimatrix game with 0-1 coefficients.
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Stable Policy Routing with Provider Independence
(2005-02-08)Thousands of competing autonomous systems (ASes) mustcooperate with each other to provide global Internet connectivity.These ASes encode various economic, business,and performance decisions in their routing policies. The ...
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Using computational models to study texture representations in the human visual system.
(2005-02-07)Traditionally, human texture perception has been studied using artificial textures made of random-dot patterns or abstract structured elements. At the same time, computer algorithms for the synthesis of natural textures ...
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Functional Differential Geometry
(2005-02-02)Differential geometry is deceptively simple. It is surprisingly easyto get the right answer with unclear and informal symbol manipulation.To address this problem we use computer programs to communicate aprecise understanding ...
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The Security Power of the Ballot Box
(2005-02-02)We show that any function F can be securely evaluated by a protocolwith ballots and a ballot box. That is, N mutually suspicious players,each player possessing a secret input, can use ballots and a ballotbox to jointly ...
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Determining articulator configuration in voiced stop consonants by matching time-domain patterns in pitch periods
(2005-01-28)In this thesis I will be concerned with linking the observed speechsignal to the configuration of articulators.Due to the potentially rapid motion of the articulators, the speechsignal can be highly non-stationary. The ...
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Virtual Stationary Automata for Mobile Networks
(2005-01-21)We define a programming abstraction formobile networks called the Virtual Stationary Automataprogramming layer, consisting of real mobile clients, virtualtimed I/O automata called virtual stationary automata(VSAs), and a ...