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Israel Symposium on the Theory of Computing and Systems

作者： U. Feige R. Krauthgamer Department of Applied Math and Computer Science Weizmann Institute of Science Rehovot Israel

A stereoscopic family of permutations maps an m-dimensional mesh into several 1-dimensional lines, in a way that jointly preserves distance information. Specifically, consider any two points and denote their distance on the m-dimensional mesh by d. Then the distance between their images, on the line on which these images are closest together is O(d/sup m/). We initiate a systematic study of stereoscopic families of permutations. We show a construction of these families that involves the use of m+1 images. We also show that under some additional restrictions (namely adjacent points on the image lines originate at points which are not too far away on the mesh), three images are necessary in order to construct such a family for the 2-dimensional mesh. We present two applications for stereoscopic families of permutations. One application is an algorithm for routing on the mesh that guarantees delivery of each packet within a number of steps that depends upon the distance between this packet's source and destination, but is independent of the size of the mesh. Our algorithm is exceptionally simple, involves no queues, and can be used in dynamic settings in which packets are continuously generated. Another application is an extension of the construction of nonexpansive hash functions of Linial and Sasson (STOC 96) from the case of one dimensional metrics to arbitrary dimensions.

关键词： computer science Career development Upper bound Optical network units Wavelength routing

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3-D to 2-D recognition with regions

3-D to 2-D recognition with regions

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Conference on computer Vision and Pattern Recognition (CVPR)

作者： D.W. Jacobs R. Basri Research Institute NEC Limited Princeton NJ USA Department of Applied Math. Weizmann Institute of Science Rehovot Israel

This paper presents a novel approach to parts-based object recognition in the presence of occlusion. We focus on the problem of determining the pose of a 3-D object from a single 2-D image when convex parts of the object have been matched to corresponding regions in the image. We consider three types of occlusions: self-occlusion, occlusions whose locus is identified in the image, and completely arbitrary occlusions. We derive efficient algorithms for the first two cases, and characterize their performance. For the last case, we prove that the problem of finding valid poses is computationally hard, but provide an efficient, approximate algorithm. This work generalizes our previous work on region-based object recognition, which focused on the case of planar models.

关键词： Shape Image recognition Jacobian matrices National electric code Object recognition Analog computers Face recognition Career development Indexing Vocabulary

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Equals - A fast parallel implementation of a lazy language

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Journal of Functional Programming 1997年第2期7卷 183-217页

作者： Kaser, Owen Ramakrishnan, C.R. Ramakrishnan, I.V. Sekar, R.C. Dept. of Math. Stat. and Comp. Sci. Univ. of New Brunswick at Saint John Saint John NB E2L 4L5 Canada Department of Computer Science SUNY at Stony Brook Stony Brook NY 11794-4400 United States Department of Computer Science Iowa State University Ames IA 50010 United States

This paper describes EQUALS, a fast parallel implementation of a lazy functional language on a commercially available shared-memory parallel machine, the Sequent Symmetry. In contrast to previous implementations, we propagate normal form demand at compile time as well as run time, and detect parallelism automatically using strictness analysis. The EQUALS implementation indicates the effectiveness of NF-demand propagation in identifying significant parallelism and in achieving good sequential as well as parallel performance. Another important difference between EQUALS and previous implementations is the use of reference counting for memory management, instead of mark-and-sweep or copying garbage collection. Implementation results show that reference counting leads to very good scalability and low memory requirements, and offers sequential performance comparable to generational garbage collectors. We compare the performance of EQUALS with that of other parallel implementations (the 〈v, G〉-machine and GAML) as well as with the performance of SML/NJ, a sequential implementation of a strict language.

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Delay-independent stability of linear neutral systems: A Riccati equation approach 4

Delay-independent stability of linear neutral systems: A Ric...

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4th European Control Conference, ECC 1997

作者： Verriest, Erik I. Niculescu, Silviu-Iulian School of Electrical and Computer Eng. Georgia Institute of Technology AtlantaGA30332-0250 United States Applied Math. Laboratory ENSTA 32 boulevard Victor Paris Cedex 1515139 France Laboratoire d'Automatique de Grenoble France Department of Automatic Control University Politehnica Bucharest Romania

ISBN: (纸本)9783952426906

This note focuses on the problem of asymptotic stability of a class of linear neutral systems described by differential equations with delayed state. The delay is assumed unknown, but constant. Sufficient conditions for delayindependent asymptotic stability are given in terms of the existence of symmetric and positive definite solutions of a continuous Riccati algebraic matrix equation coupled with a discrete Lyapunov equation. The approach adopted here is based on a Lyapunov-Krasovskii functional technique.

关键词： Asymptotic stability

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A parallel hash-based join algorithm for a networked cluster of multiprocessor nodes

A parallel hash-based join algorithm for a networked cluster...

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IEEE Annual International computer Software and Applications Conference (COMPSAC)

作者： Yun Jiang A. Makinouchi Department of Computer Science and Math. Kurashiki University of Science and the Arts Kurashiki Okayama Japan Graduate School of Information Science and Electrical Engineering Kyushu University Fukuoka Japan

Hash joins are expensive and important operations in relational database systems. Developing parallel hash join algorithms is known as an efficient method to improve their performance. Since a parallel processing environment of a networked cluster of nodes is widely available for its advantages of low-cost, high speed and ease of use, we developed a parallel hash-based join algorithm in a networked cluster of multiprocessor nodes. The parallel hash-based join algorithm has two features. One is that it takes advantage of parallel and distributed environments in which shared-memory multiprocessor computers are nodes of a networked cluster. The other is that a distributed shared virtual space is integrated into the design of the parallel hash-based join algorithm so as to facilitate the algorithm and its implementation. In this paper, we present the ideas of design, describe the parallel hash-based join algorithm, show the performance evaluation of it, as well as give a dynamic changing message model for the presence of skew.

关键词： Clustering algorithms computer networks Algorithm design and analysis Workstations Art Concurrent computing Distributed computing Database systems Hardware computer science

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An exact quantum polynomial-time algorithm for Simon's problem

An exact quantum polynomial-time algorithm for Simon's probl...

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Israel Symposium on the Theory of Computing and Systems

作者： G. Brassard P. Hoyer Détpartement IRO Université de Montreal Montreal QUE Canada Department of Math. and Computer Science Odense University Odense Denmark

We investigate the power of quantum computers when they are required to return an answer that is guaranteed to be correct after a time that is upper-bounded by a polynomial in the worst case. We show that a natural generalization of Simon's problem can be solved in this way, whereas previous algorithms required quantum polynomial time in the expected sense only, without upper bounds on the worst-case running time. This is achieved by generalizing both Simon's and Grover's algorithms and combining them in a novel way. It follows that there is a decision problem that can be solved in exact quantum polynomial time, which would require expected exponential time on any classical bounded-error probabilistic computer if the data is supplied as a black box.

关键词： Polynomials Quantum computing Error probability Quadratic programming Algorithm design and analysis

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Benchmarking stiff ode solvers for atmospheric chemistry problems--I. Implicit vs explicit

Benchmarking stiff ode solvers for atmospheric chemistry pro...

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Proceedings of the 1995 10th EUMAC Workshop

作者： Sandu, A. Verwer, J.G. Van Loon, M. Carmichael, G.R. Potra, F.A. Dabdub, D. Seinfeld, J.H. Prog. in Appl. Math. and Compl. Sci. University of Iowa Iowa City IA 52246 United States Ctr. for Math. and Computer Science P.O. Box 94079 1090 GB Amsterdam Netherlands Ctr. Global and Regl. Environ. Res. Dept. of Chem. and Biochem. Eng. University of Iowa Iowa City IA 52246 United States Depts. of Math. and Computer Science University of Iowa Iowa City IA 52246 United States Dept. of Mech. and Aerosp. Eng. University of California Irvine Irvine CA 92717-3975 United States Department of Chemical Engineering California Institute of Technology Pasadena CA 91125 United States

In many applications of atmospheric transport-chemistry problems, a major task is the numerical integration of the stiff systems of ordinary differential equations describing the chemical transformations. This paper presents a comprehensive numerical comparison between five dedicated explicit and four implicit solvers for a set of seven benchmark problems from actual applications. The implicit solvers use sparse matrix techniques to economize on the numerical linear algebra overhead. As a result they are often more efficient than the dedicated explicit ones, particularly when approximately two or more figures of accuracy are required. In most test cases, sparse RODAS, a Rosenbrock solver, came out as most competitive in the 1% error region. Of the dedicated explicit solvers, TWOSTEP came out as best. When less than 1% accuracy is aimed at, this solver performs very efficiently for tropospheric gas-phase problems. However, like all other dedicated explicit solvers, it cannot efficiently deal with gas-liquid phase chemistry. The results presented may constitute a guide for atmospheric modelers to select a suitable integrator based on the type and dimension of their chemical mechanism and on the desired level of accuracy. Furthermore, we would like to consider this paper an open invitation for other groups to add new representative test problems to those described here and to benchmark their numerical algorithms in our standard computational environment.

关键词： Atmospheric chemistry

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Genetic algorithms used for determining belief measures and plausibility measures

Genetic algorithms used for determining belief measures and ...

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Conference of the North American Fuzzy Information Processing Society - NAFIPS

作者： Zhenyuan Wang Kwong-Sak Leung Jia Wang Dept. of Math. Hebei Univ. China Department of Computer Science & Engineering Chinese University of Hong Kong New Territories Hong Kong China Department of Computer Science Cornell University Ithaca NY USA

Regarding the Choquet integral as a multi-input single-output system, one can use a set of input-output data to determine the belief measure or plausibility measure for the Choquet integral concerned. The least square... 详细信息

ISBN: (纸本)0780340787

关键词： Genetic algorithms computer science Area measurement Current measurement Hybrid intelligent systems Fuzzy sets Fuzzy systems Image analysis Information analysis Pattern analysis

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Design and modeling of a piezo-actuated positioning mechanism

Design and modeling of a piezo-actuated positioning mechanis...

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IEEE Conference on Decision and Control

作者： J.M.T.A. Adriaens W.L. de Koning R. Banning Dept. of Appl Math. & Comput. Sci. Delft Univ. of Technol. Netherlands Department of Applied Mathematics and Computer Science Delft University of Technnology Delft Netherlands Delft Institute of Microelectronics and SubmicrontechnologyDepartment of Applied Physics Delft University of Technnology Delft Netherlands

ISBN: (纸本)0780341872

We are involved in the design and control of a 1-dimensional positioning mechanism for a range of 50 /spl mu/m and an accuracy of 30 pm. Only piezoelectric actuators can be used to manage such small displacements. However, these actuators show hysteretic behavior and lengthening saturation. The extremely small displacements are measured by means of capacitive sensors. In order to design a controller a model of the positioning mechanism and the actuators is developed. Contrary to the existing literature, in our model the hysteresis is described by a differential equation. The mechanical characteristics of the design, and therefore also of the model, are chosen such that they are practically realizable and advantageous for controller design. The final nonlinear fifth order state space model is believed to be suitable for a nonlinear control technique like feedback linearization.

关键词： Magnetic hysteresis Actuators History Differential equations Sensor phenomena and characterization Magnetic materials math.matics computer science Microelectronics Physics

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No feasible interpolation for TC/sup 0/-Frege proofs

No feasible interpolation for TC/sup 0/-Frege proofs

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Annual IEEE Symposium on Foundations of computer science

作者： M.L. Bonet T. Pitassi R. Raz Department of LSI Universidad Politécnica de Cataluña Barcelona Spain Department of Computer Science University of Arizona Tucson USA Department of Applied Math Weizmann Institute of Science USA

The interpolation method has been one of the main tools for proving lower bounds for propositional proof systems. Loosely speaking, if one can prove that a particular proof system has the feasible interpolation property, then a generic reduction can (usually) be applied to prove lower bounds for the proof system, sometimes assuming a (usually modest) complexity-theoretic assumption. In this paper, we show that this method cannot be used to obtain lower bounds for Frege systems, or even for TC/sup 0/-Frege systems. More specifically, we show that unless factoring is feasible, neither Frege nor TC/sup 0/-Frege has the feasible interpolation property. In order to carry out our argument, we show how to carry out proofs of many elementary axioms/theorems of arithmetic in polynomial-size TC/sup 0/-Frege. In particular, we show how to carry out the proof for the Chinese Remainder Theorem, which may be of independent interest. As a corollary, we obtain that TC/sup 0/-Frege as well as any proof system that polynomially simulates it, is not automatizable (under a hardness assumption).

关键词： Interpolation Polynomials Circuits Arithmetic Artificial intelligence Business process re-engineering Radio access networks Large scale integration computer science Boolean functions

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