name stringlengths 5 6 | title stringlengths 8 144 | abstract stringlengths 0 2.68k | fulltext stringlengths 1.78k 95k | keywords stringlengths 22 532 |
|---|---|---|---|---|
299468 | Axiomatic Approach to Feature Subset Selection Based on Relevance. | AbstractRelevance has traditionally been linked with feature subset selection, but formalization of this link has not been attempted. In this paper, we propose two axioms for feature subset selectionsufficiency axiom and necessity axiombased on which this link is formalized: The expected feature subset is the one which... | Introduction
The problem of feature subset selection (FSS hereafter) has long been an active research topic
within statistics and pattern recognition (e.g., [9]), but most work in this area has dealt with
linear regression. In the past few years, researchers in machine learning have realised (see for
example, [18, 16])... | relevance;knowledge discovery;machine learning;entropy;feature subset selection |
299846 | Synthesizing Efficient Out-of-Core Programs for Block Recursive Algorithms Using Block-Cyclic Data Distributions. | AbstractIn this paper, we present a framework for synthesizing I/O efficient out-of-core programs for block recursive algorithms, such as the fast Fourier transform (FFT) and block matrix transposition algorithms. Our framework uses an algebraic representation which is based on tensor products and other matrix operatio... | Introduction
Due to the rapid increase in the performance of processors and communication networks in the last two
decades, the cost of memory access has become the main bottleneck in achieving high-performance for
many applications. Modern computers, including parallel computers, use a sophisticated memory hierarchy
c... | tensor product;block recursive algorithm;data distribution;program synthesis;fast Fourier transform;Parallel I/O |
299871 | Genericity, Randomness, and Polynomial-Time Approximations. | Polynomial-time safe and unsafe approximations for intractable sets were introduced by Meyer and Paterson [Technical Report TM-126, Laboratory for Computer Science, MIT, Cambridge, MA, 1979] and Yesha [SIAM J. Comput., 12 (1983), pp. 411--425], respectively. The question of which sets have optimal safe and unsafe appro... | Introduction
. The notion of polynomial-time safe approximations was introduced
by Meyer and Paterson in [13] (see also [8]). A safe approximation algorithm
for a set A is a polynomial-time algorithm M that on each input x outputs either
do not know) such that all inputs accepted by M are
members of A and no member of ... | resource bounded genericity;resource bounded randomness;approximation;computational complexity |
299878 | Reconstructing Algebraic Functions from Mixed Data. | We consider a variant of the traditional task of explicitly reconstructing algebraic functions from black box representations. In the traditional setting for such problems, one is given access to an unknown function f that is represented by a black box, or an oracle, which can be queried for the value of f at any input... | Introduction
. Suppose you are given a large set of points in the plane and
are told that an overwhelming majority of these points lie on one of k different
algebraic curves of some specified degree bound D (but you are not told anything
else about the curves). Given the parameters k and D, your task is to determine or... | bezout's theorem;polynomial interpolation;polynomial factoring;error correcting codes;multivariate polynomials;PAC learning;noisy interpolation |
300125 | A Compression Algorithm for Probability Transition Matrices. | This paper describes a compression algorithm for probability transition matrices. The compressed matrix is itself a probability transition matrix. In general the compression is not error free, but the error appears to be small even for high levels of compression. | Introduction
. Many discrete systems can be described by a Markov chain
model in which each state of the Markov model is some discrete state of the dynamical
system. If there are N states, then the Markov chain model is defined by an N \Theta N
matrix Q called the "1-step probability transition matrix," where Q(i; j) i... | lumping;transient behavior;probability transition matrix;aggregation;compression |
300138 | Using Generalized Cayley Transformations within an Inexact Rational Krylov Sequence Method. | The rational Krylov sequence (RKS) method is a generalization of Arnoldi's method. It constructs an orthogonal reduction of a matrix pencil into an upper Hessenberg pencil. The RKS method is useful when the matrix pencil may be efficiently factored. This paper considers approximately solving the resulting linear system... | Introduction
. Suppose that a few eigenvalues near a complex number - and
possibly corresponding eigenvectors of the generalized matrix eigenvalue problem
are needed. Assume that both A and B are large complex matrices of order n:
Also suppose that at least one of A or B is nonsingular so that equation (1.1) has
eigenv... | arnoldi method;rational Krylov sequence;eigenvalues;cayley transformation;generalized eigenvalue problem |
300160 | Consistent Initial Condition Calculation for Differential-Algebraic Systems. | In this paper we describe a new algorithm for the calculation of consistent initial conditions for a class of systems of differential-algebraic equations which includes semi-explicit index-one systems. We consider initial condition problems of two types---one where the differential variables are specified, and one whe... | Introduction
. This paper is concerned with the calculation of initial conditions for systems
of differential-algebraic equations (DAEs). We write the DAE system in the general form
G(t;
G, y, and y 0 are N-dimensional vectors. The initial value problem for this system is the
problem of finding a solution that satisfie... | differential-algebraic equations;consistent initial conditions |
300162 | An Efficient Newton-Type Iteration for the Numerical Solution of Highly Oscillatory Constrained Multibody Dynamic Systems. | In this paper we present a coordinate-split (CS) technique for the numerical solution of the equations of motion of constrained multibody dynamic systems. We show how the CS technique can be implemented within the context of commonly used solution methods, for increased efficiency and reliability.A particularly challe... | Introduction
The equations of motion of a constrained multibody system can be written as [10]
are the generalized coordinates, - 1 , - 2 , ., -m ] are the
Lagrange multipliers, M(q) 2 IR n\Thetan is the mass-inertia matrix, f 2 IR n is the force
applied to the system, -
dt
is the velocity and -
is the acceleration vect... | highly oscillatory systems;error bound;differential-algebraic equations;initial value problems;multibody systems |
300169 | Exponential Integrators for Large Systems of Differential Equations. | We study the numerical integration of large stiff systems of differential equations by methods that use matrix--vector products with the exponential or a related function of the Jacobian. For large problems, these can be approximated by Krylov subspace methods, which typically converge faster than those for the solutio... | Introduction
. The idea to use the exponential function of the Jacobian in a
numerical integrator is by no means new, but it has mostly been regarded as rather
impractical. Since the mid-eighties, Krylov subspace approximations to the action of
the matrix exponential operator have, however, been found to be useful in C... | high-dimensional differential equations;numerical integrator;matrix exponential;krylov subspace methods |
300180 | Circumventing Storage Limitations in Variational Data Assimilation Studies. | An application of Pontryagin's maximum principle data assimilation is used to blend possibly incomplete or nonuniformly distributed spatio-temporal observational data into geophysical models. Used extensively in engineering control theory applications, data assimilation has been introduced relatively recently into mete... | Introduction
Data assimilation has relatively recently become an important tool in many areas of
geophysics, such as weather and climate forecasting[1-6]; model sensitivity-to-parameter
studies[7,8], in the inclusion of field data sets into theoretical model-studies [9-11]. In
weather forecasting field data that may be... | gradient;variational data assimilation;storage;recursion;adjoint model;natural resources recovery;climate;meteorology |
300255 | Selected Research Issues in Decision Support Databases. | A flurry of buzzwords awaits anyone investigating database technology for decision support: data warehouse, multidimensional and dimensional database, on-line analytical processing, star schema, slicing, dicing, drill-down and roll-up. We introduce the area via an example based on a long-ago project to design a reposit... | Introduction
Decision-support databases raise issues that are often quite distinct from those
encountered in transaction processing systems. In this paper we present what we
regard as important areas for research and development for decision-support
databases, particularly those aspects that arise from the dimensional ... | dimensional;databases;decision-support;data warehouse;multidimensional |
300521 | The integrality of speech in multimodal interfaces. | A framework of complementary behavior has been proposed which maintains that direct-manipulation and speech interfaces have reciprocal strengths and weaknesses. This suggests that user interface performance and acceptance may increase by adopting a multimodal approach that combines speech and direct manipulation. This ... | Figure
2: Proposed Applications for Direct Manipulation and Speech
Contrastive Functionality
A study by Oviatt and Olsen [1994] examined how people might combine input from
different devices in a multimodal computer interface. The study used a simulated service
transaction system with verbal, temporal, and computation... | medical informatics;speech recognition;natural-language processing;integrality;multimodal;separability;direct manipulution;pathology;perceptual structure;input devices |
300896 | Sensitivity Analysis of Optimization Problems Under Second Order Regular Constraints. | We present a perturbation theory for finite dimensional optimization problems subject to abstract constraints satisfying a second order regularity condition. This is a technical condition that is always satisfied in the case of semi-definite optimization. We derive Lipschitz and Holder expansions of approximate optimal... | Introduction
In this paper we present a theory that allows to compute the asymptotic expansions of the
optimal value function v(u), as well as the optimal or "nearly optimal" solutions x(u) of
parametric optimization problems of the form
f(x; u) subject to G(x; u) 2 K:
While the theory is fairly complete in the framewo... | parametric optimization;semi-definite programming;directional constraint qualification;semi-infinite programming;directional differentiability;sensitivity analysis;metric projection;optimal value function;second order optimality conditions |
301117 | Predictive analysis of a wavefront application using LogGP. | This paper develops a highly accurate LogGP model of a complex wavefront application that uses MPI communication on the IBM SP/2. Key features of the model include: (1) elucidation of the principal wavefront synchronization structure, and (2) explicit high-fidelity models of the MPI-send and MPI-receive primitives. The... | INTRODUCTION
This paper investigates the use of the parallel machine model
called LogGP to analyze the performance of a large, complex
application on a state-of-the-art commercial parallel platform.
The application, known as Sweep3D, is of interest because it is a
three-dimensional particle transport problem that has b... | particle transport applications;parallel algorithms;logp model;parallel application performance |
301118 | Performance prediction of large parallel applications using parallel simulations. | Accurate simulation of large parallel applications can be facilitated with the use of direct execution and parallel discrete event simulation. This paper describes the use of COMPASS, a direct execution-driven, parallel simulator for performance prediction of programs that include both communication and I/O intensive a... | INTRODUCTION
Accurate and efficient performance prediction of existing parallel
applications on multiple target architectures is a challenging
problem. Both analytical and simulation approaches have been
used successfully for this purpose. Whereas analytical solutions
have the advantage of efficiency, they also suffer ... | MPI;application scalability;MPI-IO;parallel program simulation;direct execution;parallel discrete event simulation |
301412 | Parsimonious Least Norm Approximation. | A theoretically justifiable fast finite successive linear approximation algorithm is proposed for obtaining a parsimonious solutionto a corrupted linear system Ax=b+p, where the corruptionp is due to noise or error in measurement. The proposedlinear-programming-based algorithm finds a solutionx by parametrically minimi... | Introduction
A wide range of important applications can be reduced to the problem of estimating a vector x by
minimizing some norm of the residual vector Ax \Gamma b arising from a possibly inconsistent system of
linear equations:
where A is an m \Theta n real matrix and b is an m \Theta 1 vector, and both A and b are ... | minimal cardinality;least norm approximation |
301463 | On learning algorithms and balancing loads in Time Warp. | We present, in this paper, an algorithm which integrates flow control and dynamic load balancing in order to improve the performance and stability of Time Warp. The algorithm is intended for use in a distributed memory environment such as a cluster of workstations connected by a high speed switch. Our flow control algo... | Introduction
The synchronization algorithm for Time Warp [9] involves
rolling the simulation back to a previous state if
an event arrives at a simulation object (an LP, or logical
process) with a timestamp which is smaller than that
of a previously processed event. In order to accomplish
this, Time Warp periodically re... | flow control;time warp;space-time product;dynamic load balancing;stochastic learning automata;stability;GVT |
301668 | New tiling techniques to improve cache temporal locality. | Tiling is a well-known loop transformation to improve temporal locality of nested loops. Current compiler algorithms for tiling are limited to loops which are perfectly nested or can be transformed, in trivial ways, into a perfect nest. This paper presents a number of program transformations to enable tiling for a clas... | Introduction
Due to the widening gap between processor and memory
speed, the importance of efficient use of caches
is widely recognized. Loop tiling, which combines
strip-mining and loop interchange, is a well-known
loop transformation which can be used to increase the
This work is sponsored in part by National Science... | optimizing compilers;caches;loop transformations |
301669 | A Modified Cholesky Algorithm Based on a Symmetric Indefinite Factorization. | Given a symmetric and not necessarily positive definite matrix A, a modified Cholesky algorithm computes a Cholesky factorization permutation matrix and E is a perturbation chosen to make A+E positive definite. The aims include producing a small-normed E and making A+E reasonably well conditioned. Modified Cholesky fac... | Introduction
. Modified Cholesky factorization is a widely used technique in
optimization; it is used for dealing with indefinite Hessians in Newton methods [11],
[21] and for computing positive definite preconditioners [6], [20]. Given a symmetric
matrix A, a modified Cholesky algorithm produces a symmetric perturbati... | modified Cholesky factorization;newton's method;symmetric indefinite factorization;optimization |
301971 | The computational complexity of knot and link problems. | We consider the problem of deciding whether a polygonal knot in 3-dimensional Euclidean space is unknotted, ie., capable of being continuously deformed without self-intersection so that it lies in a plane. We show that this problem, UNKNOTTING PROBLEM is in NP. We also consider the problem, SPLITTING PROBLEM of determi... | Introduction
The problems dealt with in this paper might reasonably be called "computational topology";
that is, we study classical problems of topology (specifically, the topology of 1-dimensional
curves in 3-dimensional space) with the objective of determining their computational complex-
ity. One of the oldest and m... | three-dimensional topology;computational complexity;knot theory |
302245 | Likelihood Ratio Derivative Estimation for Finite-Time Performance Measures in Generalized Semi-Markov Processes. | This paper investigates the likelihood ratio method for estimating derivatives of finite-time performance measures in generalized semi-Markov processes (GSMPs). We develop readily verifiable conditions for the applicability of this method. Our conditions mainly place restrictions on the basic building blocks (i.e., the... | Introduction
When running a simulation, one is often interested in estimating derivatives of a performance
measure with respect to parameters of the input distributions (e.g., routing probabilities,
time distributions and service time distributions in queueing networks; lifetime
distributions and repair time distributi... | gradient estimation;Generalized Semi-Markov Processes;simulation |
302948 | A Robust Competitive Clustering Algorithm With Applications in Computer Vision. | AbstractThis paper addresses three major issues associated with conventional partitional clustering, namely, sensitivity to initialization, difficulty in determining the number of clusters, and sensitivity to noise and outliers. The proposed Robust Competitive Agglomeration (RCA) algorithm starts with a large number of... | Introduction
Traditional clustering algorithms can be classified into two main categories [1]: hierarchical
and partitional. In hierarchical clustering, the number of clusters need not be specified a
priori, and problems due to initialization and local minima do not arise. However, since
hierarchical methods consider o... | robust clustering;robust statistics;motion estimation;optimal number of clusters;range image segmentation;linear regression;fuzzy clustering;competitive clustering |
303080 | Edge-Connectivity Augmentation Preserving Simplicity. | Given a simple graph G=(V,E), our goal is to find a smallest set F of new edges such that G=(V,E\cup F) is k-edge-connected and simple. Recently this problem was shown to be NP-complete. In this paper we prove that if OPT_P^k$ is high enough---depending on k only---then OPT _S^k= OPT_P^k$ holds, where OPT_S^k$ (OPT_P^... | Introduction
In the last decade several graph augmentation problems have been investigated. Especially
the connectivity augmentation problems attracted considerable attention due to the various
connections to the so-called network design problems which model the survivability
problems of (telephone or computer, etc) ne... | edge-connectivity augmentation of graphs;network design;combinatorial optimization;connectivity |
303158 | Visualizing implicit queries for information management and retrieval. | In this paper, we describe the use of similarity metrics in a novel visual environment for storing and retrieving favorite web pages. The similarity metrics, called Implicit Queries, are used to automatically highlight stored web pages that are related to the currently selected web page. Two experiments explored how us... | Figure
1. Data Mountain with Implicit Query results
shown (highlighted pages to left of selected page).
graphics (e.g., a company logo) that users might associate
in memory with that page. To take advantage of this, we
present a visualization that allows users to manually create
a spatial layout of the thumbnails of t... | classification;similarity;categorization;information retrieval;information management;information visualization |
303650 | Optimal Control of Thermally Convected Fluid Flows. | We examine the optimal control of stationary thermally convected fluid flows from the theoretical and numerical point of view. We use thermal convection as control mechanism; that is, control is effected through the temperature on part of the boundary. Control problems are formulated as constrained minimization probl... | Introduction
. The control of viscous flows for the purpose of achieving some desired
objective is crucial to many technological and scientific applications. In the past,
these control problems have been addressed either through expensive experimental processes
or through the introduction of significant simplifications... | flow control;finite element methods;temperature control;optimization;navier-stokes equations |
303657 | Space-Time Continuous Analysis of Waveform Relaxation for the Heat Equation. | Waveform relaxation algorithms for partial differential equations (PDEs) are traditionally obtained by discretizing the PDE in space and then splitting the discrete operator using matrix splittings. For the semidiscrete heat equation one can show linear convergence on unbounded time intervals and superlinear convergenc... | Introduction
. The basic ideas of waveform relaxation were introduced in
the late 19th century by Picard [18] and Lindel-of [11] to study initial value problems.
There has been much recent interest in waveform relaxation as a practical parallel
method for the solution of stiff ordinary differential equations (ODEs) aft... | overlapping Schwarz;multisplitting;domain decomposition;waveform relaxation |
303658 | Asymptotic-Induced Domain Decomposition Methods for Kinetic and Drift Diffusion Semiconductor Equations. | This paper deals with domain decomposition methods for kinetic and drift diffusion semiconductor equations. In particular accurate coupling conditions at the interface between the kinetic and drift diffusion domain are given. The cases of slight and strong nonequilibrium situations at the interface are considered and ... | Introduction
Semiconductor device simulations are usually done on the basis of drift diffusion
or hydrodynamic equations. However in view of the ongoing miniaturization
of semiconductor devices a more accurate modelling of the physics seems to be
necessary. This is achieved by kinetic semiconductor equations. We refer ... | kinetic semiconductor equations;asymptotic analysis;domain decomposition methods;drift-diffusion equation |
303660 | The Perfectly Matched Layer in Curvilinear Coordinates. | In 1994 Brenger showed how to construct a perfectly matched absorbing layer for the Maxwell system in rectilinear coordinates. This layer absorbs waves of any wavelength and any frequency without reflection and thus can be used to artificially terminate the domain of scattering calculations. In this paper we show how... | Introduction
.
Finite element, finite difference or finite volume discretizations of scattering
problems are faced with the problem of truncating the infinite domain problem
without introducing excessive error into the computed solution. Usually
an artificial boundary is introduced on which a special absorbing boundary... | perfectly matched layer;finite element;absorbing layer |
305008 | Integrated Range Comparison for Data-Parallel Compilation Systems. | AbstractA major difficulty in restructuring compilation, and in parallel programming in general, is how to compare parallel performance over a range of system and problem sizes. Execution time varies with system and problem size and an initially fast implementation may become slow when system and problem size scale up.... | Introduction
The most significant question with parallel machines is the same today as it has been for many
decades: How can software applications take advantage of hardware parallelism [1]. Traditionally,
distributed memory architectures have been programmed using message passing where the user
is responsible for expl... | scalable computing;performance evaluation;parallel compiler;software systems |
305009 | Redundant Synchronization Elimination for DOACROSS Loops. | AbstractCross-iterations data dependences in DOACROSS loops require explicit data synchronizations to enforce them. However, the composite effect of some data synchronizations may cover the other dependences and make the enforcement of those covered dependences redundant. In this paper, we propose an efficient and gene... | Introduction
Concurrent execution of loops with cross-iteration data dependences, termed DOACROSS loops, allows us to exploit
more loop-level parallelism beyond the vector loops and the DOALL loops in application programs. As the machine size is
becoming larger, exploitingmore parallelism in a programbecomes more impor... | DOACROSS;compiler optimization;redundant synchronization elimination;data synchronization;data dependence |
305011 | How to Sort N Items Using a Sorting Network of Fixed I/O Size. | AbstractSorting networks of fixed I/O size p have been used, thus far, for sorting a set of p elements. Somewhat surprisingly, the important problem of using such a sorting network for sorting arbitrarily large data sets has not been addressed in the literature. Our main contribution is to propose a simple sorting arch... | Introduction
Sorting networks are a well studied class of parallel sorting devices. For an early treatment of the
subject, see [4, 12]; for recent surveys we refer the reader to [2, 3, 7, 19, 22, 23]. In general, sorting
networks are suitable for VLSI realization. This is due, in part, to the fact that the processing
e... | pipelined processing;sorting networks;computer architecture;parallel processing;sorting |
305093 | Asynchronous Parallel Prefix Computation. | AbstractThe prefix problem is to compute all the products $x_1 \otimes x_2 \otimes \cdots \otimes x_k,$ for 1 kn, where $\otimes$ is an associative binary operation. We start with an asynchronous circuit to solve this problem with O(log n) latency and O(n log n) circuit size, with $O(n)\ \otimes\!\!-{\rm operations}$ i... | Introduction
There has been a renewal of interest in the design of asynchronous circuits, motivated by the potential
benefits of designing circuits in an asynchronous fashion. Asynchronous circuits exhibit average case
behavior and can therefore be optimized in a data-dependent fashion. We present asynchronous solution... | binary addition;asynchronous circuits;prefix computation;average-case latency |
305097 | Interactive Orthogonal Graph Drawing. | AbstractMany applications require human interaction during the design process. The user is given the ability to alter the graph as the design progresses. Interactive Graph Drawing allows the user to dynamically interact with the drawing of a graph. In this paper, we discuss features that are essential for an interactiv... | Introduction
Graphs have been extensively used to represent various important concepts or objects. Examples
include parallel computer architectures, networks, state graphs, entity-relationship
diagrams, subroutine call graphs, automata, data-flow graphs, Petri nets, VLSI circuits,
etc. In all of these cases, we require... | graphical user interface;orthogonal graph drawing;interactive orthogonal graph drawing;information visualization;graph drawing |
305116 | Broadcasting Multiple Messages in the Multiport Model. | AbstractWe consider the problem of broadcasting multiple messages from one processor to many processors in the $k$-port model for message-passing systems. In such systems, processors communicate in rounds, where in every round, each processor can send $k$ messages to $k$ processors and receive $k$ messages from $k$ pro... | Introduction
This paper explores the broadcast problem in the multiport model for message-passing systems.
In particular, we consider (one-to-all) broadcast problem on a message-passing system modeled
by a complete graph of n nodes with k-port model. We assume that there are n processors
(nodes) in the system, denoted ... | multiport model;message-passing system;one-to-all broadcast;broadcast;collective communication |
305222 | Atomic Decomposition by Basis Pursuit. | The time-frequency and time-scale communities have recently developed a large number of overcomplete waveform dictionaries --- stationary wavelets, wavelet packets, cosine packets, chirplets, and warplets, to name a few. Decomposition into overcomplete systems is not unique, and several methods for decomposition have ... | Introduction
Over the last several years, there has been an explosion of interest in alternatives to traditional
signal representations. Instead of just representing signals as superpositions of
sinusoids (the traditional Fourier representation) we now have available alternate dictionaries
- collections of parameterize... | matching pursuit;time-frequency analysis;overcomplete signal representation;multiscale edges;time-scale analysis;interior-point methods for linear programming;denoising;wavelet packets;wavelets;total variation denoising;ell1 norm optimization;cosine packets |
305225 | Jacobi--Davidson Style QR and QZ Algorithms for the Reduction of Matrix Pencils. | Recently the Jacobi--Davidson subspace iteration method has been introduced as a new powerful technique for solving a variety of eigenproblems. In this paper we will further exploit this method and enhance it with several techniques so that practical and accurate algorithms are obtained. We will present two algorithms,... | Introduction
. In this paper we expand on the usage of the Jacobi-Davidson
method [26], [24] for the computation of several solutions of the generalized eigenproblem(# A-
(1)
where A and B are large and sparse (n n)-matrices, which may be complex and/or
nonnormal. We will also discuss the standard eigenproblem
(2)
Of c... | linear eigenproblems;generalized eigenproblems;QZ-algorithm;jacobi-davidson;generalized Schur form;schur form;iterative methods;QR-algorithm |
305235 | The Lack of Influence of the Right-Hand Side on the Accuracy of Linear System Solution. | It is commonly believed that a fortunate right-hand side b can significantly reduce the sensitivity of a system of linear equations Ax=b. We show, both theoretically and experimentally, that this is not true when the system is solved (in floating point arithmetic) with Gaussian elimination or the QR factorization: the ... | Introduction
. When a system of linear equations solved numeri-
cally, the accuracy of the computed solution generally depends on the sensitivity of
the linear system to perturbations. In this paper we examine how the right-hand side
b affects the sensitivity of the linear system and the error estimates.
Suppose the ma... | condition number;right-hand side;stopping criterion;backward error;linear system |
305238 | Adaptively Preconditioned GMRES Algorithms. | The restarted GMRES algorithm proposed by Saad and Schultz [SIAM J. Sci. Statist. Comput., 7 (1986), pp. 856--869] is one of the most popular iterative methods for the solution of large linear systems of equations Ax=b with a nonsymmetric and sparse matrix. This algorithm is particularly attractive when a good precondi... | Introduction
. Many problems in Applied Mathematics and Engineering give
rise to very large linear systems of equations
with a sparse nonsymmetric nonsingular matrix A. It is often desirable, and sometimes
necessary, to solve these systems by an iterative method. Let x 0 be an initial
approximate solution of (1.1), and... | arnoldi process;iterative method;preconditioner;nonsymmetric linear system |
305240 | Algorithms for Model-Based Gaussian Hierarchical Clustering. | Agglomerative hierarchical clustering methods based on Gaussian probability models have recently shown promise in a variety of applications. In this approach, a maximum-likelihood pair of clusters is chosen for merging at each stage. Unlike classical methods, model-based methods reduce to a recurrence relation only in ... | Introduction
Multivariate Gaussian models have been proposed for quite some time as a basis for clustering
algorithms. Recently, methods of this type have shown promise in a number of practical
applications [9]. Examples in the geophysical sciences include seismic data processing, in the
biological sciences classificat... | hierarchical agglomeration;mixture models;model-based cluster analysis |
305246 | Parallel Hierarchical Solvers and Preconditioners for Boundary Element Methods. | The method of moments is an important tool for solving boundary integral equations arising in a variety of applications. It transforms the physical problem into a dense linear system. Due to the large number of variables and the associated computational requirements, these systems are solved iteratively using methods s... | Introduction
The method of moments [12] is a popular method for solving integral equations. It has
extensive applications in computational electromagnetics, wave propagation, and heat
transfer [22, 21, 3, 11]. It transforms a physical problem defined as an integral equation
into a dense linear system. The integral equa... | dense iterative solver;fast multipole method;barnes-hut method;preconditioning boundary element methods;parallel treecode;hierarchical dense matrix-vector product;boundary element method |
305274 | Equivalence of Nonlinear Systems to Prime Systems under Generalized Output Transformations. | Within a linear algebraic framework, we present a new characterization of the class of nonlinear systems which are equivalent to a prime system. We then introduce a class of generalized output transformations that can be thought of as a generalization to the nonlinear setting of a unimodular transformation in the outp... | Introduction
. The problem of characterizing the class of linear systems that
are equivalent to prime systems was first posed and solved by Morse [12]. The group of
transformations considered in [12] included, besides state space change of coordinates
and linear state feedback, output space change of coordinates. Marin... | prime systems;nonlinear systems;differential forms;output transformation |
305308 | Stabilized Finite Element Formulations for Shells in a Bending Dominated State. | We consider the design of finite element methods for the Naghdi shell model in the case when the deformation is bending dominated. Two formulations based on stabilizing techniques are introduced and it is proved that they are stable, hence free from locking. The theoretical estimates are confirmed by numerical benchm... | Introduction
During the last decade great progress has been obtained in the understanding of the
locking of finite element methods for various "thin structures". For one-dimensional
problems, i.e. beams and arches, it is now completely known how "locking-free"
finite element methods should be constructed, cf. e.g. [1, ... | stabilized methods;naghdi model;shells;finite element methods |
305311 | Convergence of Moment Methods for Linear Kinetic Equations. | Numerical methods for linear kinetic equations based on moment expansions for a discretization in the velocity direction are examined. The moment equations are hyperbolic systems which can be shown to converge to the kinetic equation as the order of the expansion tends to infinity and to a drift-diffusion model as the ... | Introduction
The numerical simulation of flows governed by macroscopic models in certain
subdomains and by kinetic models in others, has received significant attention
recently. Applications can be found in the fields of gas dynamics and
semiconductor device simulation. One obvious approach to these problems
is domain ... | moment expansion;semiconductors;kinetic equations |
305323 | Preserving Symmetry in Preconditioned Krylov Subspace Methods. | We consider the problem of solving a linear system A when A is nearly symmetric and when the system is preconditioned by a symmetric positive definite matrix M. In the symmetric case, we can recover symmetry by using M-inner products in the conjugate gradient (CG) algorithm. This idea can also be used in the nonsymmetr... | Introduction
Consider the solution of the linear system
by a preconditioned Krylov subspace method. Assume at first that A is symmetric positive
definite (SPD) and let M be an SPD matrix that is a preconditioner for the matrix A. Then
one possibility is to solve either the left-preconditioned system
This work was suppo... | preconditioned iterative methods;inner-products;incomplete orthogonalization |
305327 | On the Solution of Convection-Diffusion Boundary Value Problems Using Equidistributed Grids. | The effect of using grid adaptation on the numerical solution of model convection-diffusion equations with a conservation form is studied. The grid adaptation technique studied is based on moving a fixed number of mesh points to equidistribute a generalization of the arc-length of the solution. In particular, a paramet... | Introduction
The solution of boundary value problems (BVPs) using finite difference
methods consists of discretizing the differential equations on a finite mesh
and solving the system of equations for the values of the functions at these
mesh locations. Adaptive meshes are widely utilized for problems containing
strong... | continuation;convection-diffusion equations;mesh adaptation;equidistribution |
305365 | The Chebyshev Polynomials of a Matrix. | A Chebyshev polynomial of a square matrix A is a monic polynomial p of specified degree that minimizes |p (A)|2. The study of such polynomials is motivated by the analysis of Krylov subspace iterations in numerical linear algebra. An algorithm is presented for computing these polynomials based on reduction to a semid... | Introduction
. Let A be an N \Theta N matrix and n a nonnegative integer. The
degree n Chebyshev polynomial of A is the unique monic polynomial p
n of degree n
such that
(1)
denotes the matrix 2-norm. To be precise, p
n is unique provided that n is
less than or equal to the degree of the minimal polynomial of A; otherw... | matrix polynomial;krylov subspace iteration;chebyshev polynomial of a matrix;semidefinite programming |
305406 | Threads Yield Continuations. | Just as a traditional continuation represents the rest of a computation from a given point in the computation, a subcontinuation represents the rest of a subcomputation from a given point in the subcomputation. Subcontinuations are more expressive than traditional continuations and have been shown to be useful for cont... | Introduction
Continuations have proven useful for implementing a variety of control
structures, such as nonlocal exits, exceptions, nonblind backtracking [28],
This material is based on work supported in part by the National Science Foundation
under grant numbers CDA-9312614 and CDA 93-03189.
nondeterministic computati... | continuations;concurrency;control operators;control delimiters;threads |
305664 | Adaptive Mesh Refinement Using Wave-Propagation Algorithms for Hyperbolic Systems. | An adaptive mesh refinement algorithm developed for the Euler equations of gas dynamics has been extended to employ high-resolution wave-propagation algorithms in a more general framework. This allows its use on a variety of new problems, including hyperbolic equations not in conservation form, problems with source te... | Introduction
The multi-dimensional wave-propagation algorithm described in [14] is a "high-resolution" method
that is second order accurate on smooth solutions while maintaining sharp discontinuities through
the use of slope-limiters. While based on ideas developed for hyperbolic systems of conservation
laws
in the con... | software;finite-volume methods;hyperbolic conservation laws;gas dynamics;high resolution;godunov;adaptive mesh refinement;acoustics |
305727 | Three-Processor Tasks Are Undecidable. | We show that no algorithm exists for deciding whether a finite task for three or more processors is wait-free solvable in the asynchronous read-write shared-memory model. This impossibility result implies that there is no constructive (recursive) characterization of wait-free solvable tasks. It also applies to other sh... | Introduction
A fundamental area in the theory of distributed computation is the study
of asynchronous wait-free shared-memory distributed algorithms. Characterizing
the class of distributed tasks that can be solved, no matter how
"inefficiently", is an important step towards a complexity theory for distributed
computat... | contractibility problem;task-solvability;asynchronous distributed computation;wait-free computation |
305747 | Products and Help Bits in Decision Trees. | We investigate two problems concerning the complexity of evaluating a function f on k distinct inputs by k parallel decision-tree algorithms.In the product problem, for some fixed depth bound d, we seek to maximize the fraction of input k-tuples for which all k decision trees are correct. Assume that for a single inp... | Introduction
Pick your favorite computation model and complexity
measure, e.g. boolean circuit size, communication
complexity, decision tree depth, interactive proof
length, tensor rank, etc. Any attempt to understand
such a model and complexity measure requires understanding
the ways that an "unreasonable" computation... | help bits;decision trees |
305750 | Competitive On-Line Algorithms for Distributed Data Management. | Competitive on-line algorithms for data management in a network of processors are studied in this paper. A data object such as a file or a page of virtual memory is to be read and updated by various processors in the network. The goal is to minimize the communication costs incurred in serving a sequence of such request... | Introduction
. The management of data in a distributed network is an important
and much studied problem in management science, engineering, computer
systems and theory [3, 11]. Dowdy and Foster [11] give a comprehensive survey of
research in this area, listing eighteen different models and many papers. A data ob-
ject,... | memory management;data management;competitive analysis;on-line algorithms |
305974 | Exploiting Discontinuities in Optical Flow. | Most optical flow estimation techniques have substantial difficulties dealing with flow discontinuities. Methods which simultaneously detect flow boundaries and use the detected boundaries to aid in flow estimation can produce significantly improved results. Current approaches to implementing these methods still have i... | Introduction
Discontinuities in optical flow are normally viewed
as a serious impediment to producing accurate estimates
of the flow. Due to the ambiguous nature
of flow within small space-time neighborhoods of
an image sequence, all methods for estimating flow
either explicitly or implicitly assume some sort of
spatia... | visual motion;discontinuities;optical flow;edges |
305984 | Relaxing the Triangle Inequality in Pattern Matching. | Any notion of closeness in pattern matching should have the property that if A is close to B, and B is close to C, then A is close to C. Traditionally, this property is attained because of the triangle inequality d(B, C), where d represents a notion of distance). However, the full power of the triangle inequality is no... | Introduction
Traditionally, databases have been used to store and retrieve textual and numerical information.
More recently, applications such as multimedia have led to the development of database systems that
can handle images. One such system is the QBIC ("Query by Image Content") system (Niblack
et al., 1993), devel... | image database;distance measure;triangle inequality;shape matching;pattern matching |
306216 | Conjectural Equilibrium in Multiagent Learning. | Learning in a multiagent environment is complicated by the fact that as other agents learn, the environment effectively changes. Moreover, other agents actions are often not directly observable, and the actions taken by the learning agent can strongly bias which range of behaviors are encountered. We define the concept... | Introduction
Machine learning researchers have recently begun to investigate the special issues that
multiagent environments present to the learning task. Contributions in this journal issue,
along with recent workshops on the topic [13, 29, 30], have helped to frame research
problems for the field. Multiagent environm... | market game;conjectural equilibrium;multiagent learning |
306259 | Elevator Group Control Using Multiple Reinforcement Learning Agents. | Recent algorithmic and theoretical advances in reinforcement learning (RL) have attracted widespread interest. RL algorithms have appeared that approximate dynamic programming on an incremental basis. They can be trained on the basis of real or simulated experiences, focusing their computation on areas of state space t... | Introduction
Interest in developing capable learning systems is increasing within the multi-agent
and AI research communities (e.g., Weiss & Sen, 1996). Learning enables systems
to be more flexible and robust, and it makes them better able to handle uncertainty
and changing circumstances. This is especially important i... | discrete event dynamic systems;reinforcement learning;elevator group control;teams;multiple agents |
306628 | Generating Quasi-Random Paths for Stochastic Processes. | The need to simulate stochastic processes numerically arises in many fields. Frequently this is done by discretizing the process into small time steps and applying pseudorandom sequences to simulate the randomness. This paper addresses the question of how to use quasi-Monte Carlo methods to improve this simulation. S... | Introduction
In many applications ranging from finance to fluid dynamics it is necessary
to evaluate the expectation of a function of a random path generated by a
stochastic process. For a continuous time process this expectation may often be
expressed as a Feynman-Kac type integral over Brownian motion. For numerical
... | quasi-Monte Carlo;stochastic process simulation;computational finance |
306669 | A Behavior Model for Next Generation Test Systems. | Defining information required by automatic test systems frequently involves a description of system behavior. To facilitate capturing the required behavior information in the context of testing, a formal model of behavior was developed for use by test systems. The approach taken in defining the behavior model was based... | INTRODUCTION
Defining information required by automatic test systems frequently involves a description
of system behavior in one way or another. Behavior is a characteristic of an entity that describes
how that entity acts or reacts within some context or environment. Within the context of test
systems, behavior is def... | automatic test systems;test programming;test requirements;behavior modeling |
306890 | Dynamic Reconfiguration to Support Concurrent Applications. | AbstractThis paper describes the development of a dynamically reconfigurable system that can support multiple applications running concurrently. A dynamically reconfigurable system allows hardware reconfiguration while part of the reconfigurable hardware is busy computing. An FPGA resource manager (RM) is developed to ... | Introduction
Adaptive Computing Systems (ACS) have been shown
to outperform general-purpose systems for some applications
because of their abilities in adapting hardware resources
to the application requirements[1], [8], [9], [13],
[16]. The technology has been demonstrated for a few special
purpose applications which ... | reconfiguration;field programmable gate array FPGA;scheduling;resource management;configurable computing |
307960 | Constructive Quasi-Ramsey Numbers and Tournament Ranking. | A constructive lower bound on the quasi-Ramsey numbers and the tournament ranking function was obtained in [S. Poljak, V. Rdl, and J. Spencer, SIAM J. Discrete Math., (1) 1988, pp. 372--376]. We consider the weighted versions of both problems. Our method yields a polynomial time heuristic with guaranteed lower bound f... | Introduction
. The quasi-Ramsey number g(n) is defined as the maximum
discrepancy between the number of edges and nonedges that appears on some induced
subgraph of any graph of order n, i.e.,
f
a function from [n] 2 into {-1, 1} and
It is well known (Erdos and Spencer [4]) that for some positive, absolute constants
The... | linear ordering problem;discrepancy;derandomization;regularity lemma |
307963 | On-Line Difference Maximization. | In this paper we examine problems motivated by on-line financial problems and stochastic games. In particular, we consider a sequence of entirely arbitrary distinct values arriving in random order, and must devise strategies for selecting low values followed by high values in such a way as to maximize the expected gai... | Introduction
. In this paper, we examine the problem of accepting values
from an on-line source and selecting values in such a way as to maximize the difference
in the ranks of the selected values. The input values can be arbitrary distinct real
numbers, and thus we cannot determine with certainty the actual ranks of a... | financial games;analysis of algorithms;secretary problem;on-line algorithms |
307967 | Convexity and HHD-Free Graphs. | It is well known that chordal graphs can be characterized via m-convexity. In this paper we introduce the notion of m3-convexity (a relaxation of m-convexity) which is closely related to semisimplicial ordering of graphs. We present new characterizations of HHD-free graphs via m3-convexity and obtain some results known... | Introduction
. This paper was inspired by the results of Farber and Jamison
[16] on convexity in chordal graphs and by the results of Jamison and Olariu [19] on
semisimplicial orderings of graphs produced by "lexicographic breadth first search"
(LexBFS) [25] and "maximum cardinality search" (MCS) [28].
Throughout this ... | convexity;weak bipolarizable graphs;chordal graphs;convex geometry;semisimplicial ordering;antimatroid;HHD-free graphs;lexicographic breadth first search;dominating clique problem |
308003 | The Timed Asynchronous Distributed System Model. | AbstractWe propose a formal definition for thetimed asynchronous distributed system model. We present extensive measurements of actual message and process scheduling delays and hardware clock drifts. These measurements confirm that this model adequately describes current distributed systems such as a network of worksta... | Introduction
Depending on whether the underlying communication
and process management services provide "certain com-
munication", distributed systems can be classified as either
synchronous or asynchronous [7]. By certain communication
we mean that 1) at any time there is a minimum number
of correct processes, and 2) a... | communication by time;timed model;asynchronous systems;measurements;synchronous systems;distributed systems;failure model;system model |
308845 | On reducing the processing cost of on-demand QoS path computation. | Quality of Service (QoS) routing algorithms have become the focus of recent research due to their potential for increasing the utilization of an Integrated Services Packet Network (ISPN) serving requests with QoS requirements. While heuristics for determining paths for such requests have been formulated for a variety o... | Introduction
Although a considerable amount of work has been done
on the problem of supporting QoS in the network, only
recently the role that routing will play in an integrated
services network came into attention. The main body of
the QoS routing work so far focuses on the path finding
problem: given the QoS metrics,... | trunk reservation;link state routing;path caching;path pre-computation |
309102 | Global Convergence of Trust-region Interior-point Algorithms for Infinite-dimensional Nonconvex Minimization Subject to Pointwise Bounds. | A class of interior-point trust-region algorithms for infinite-dimensional nonlinear optimization subject to pointwise bounds in L p-Banach spaces, $2\le p\le\infty$, is formulated and analyzed. The problem formulation is motivated by optimal control problems with L p-controls and pointwise control constraints. The int... | Introduction
. This paper is concerned with the development and analysis
of a class of interior-point trust-region algorithms for the solution of the following
infinite-dimensional nonlinear programming problem:
minimize f(u)
subject to u
ae IR n is a domain with positive and finite Lebesgue measure
Moreover,
denotes t... | optimal control;global convergence;interior-point algorithms;affine scaling;nonlinear programming;trust-region methods;infinite-dimensional optimization;bound constraints |
309110 | Stochastic Shortest Path Games. | We consider dynamic, two-player, zero-sum games where the "minimizing" player seeks to drive an underlying finite-state dynamic system to a special terminal state along a least expected cost path. The "maximizer" seeks to interfere with the minimizer's progress so as to maximize the expected total cost. We consider, fo... | Introduction
. This paper develops basic theory relating to stochastic shortest
path games. These are two-player, zero-sum, games where the minimizing player
seeks to drive an underlying finite-state dynamic system to a special terminal state
along a least expected cost path. The maximizer seeks to interfere with the m... | game theory;stochastic games;stochastic shortest paths;optimization;dynamic programming |
309119 | Supporting Scalable Performance Monitoring and Analysis of Parallel Programs. | Tools for performance monitoring and analysis become indispensable parts of programming environments for parallel computers. As the number of processors increases, the conventional techniques for monitoring the performance of parallel programs will produce large amounts of data in the form of event trace files. On the... | Introduction
Monitoring the performance of a parallel program at run-time is an extremely useful
feature for any powerful performance tool. The existing run-time performance
monitors can only provide and display limited information for performance tuning.
One of the major reasons is that, with run-time monitoring, ther... | program instrumentation;trace data organisation;performance monitoring |
309125 | Piecewise-Constant Stabilization. | With the help of topological necessary conditions for continuous stabilization it is shown that, in general, in order to stabilize continuous- and discrete-time systems one has to use time-dependent or discontinuous feedback controls. On the other hand, the criterion of stabilization in the class of piecewise-constant ... | Introduction
. Stabilization of dynamical systems is one of the basic problems
in systems theory. In [9], [10] and [11] it is shown that many nonlinear systems
are not stabilizable by any continuous feedback of the form For the purpose
of illustration we give a geometrical interpretation of the results presented in [9]... | discrete-time system;degree of functions;nonlinear system;feedback stabilization |
309127 | Bifurcation Stabilization with Local Output Feedback. | Local output feedback stabilization with smooth nonlinear controllers is studied for parameterized nonlinear systems for which the linearized system possesses either a simple zero eigenvalue or a pair of imaginary eigenvalues and the bifurcated solution is unstable at the critical value of the parameter. It is assumed ... | Introduction
Stabilization of nonlinear control systems with smooth state feedback control has been studied by
a number of people [4, 2, 3, 9, 19]. An interesting situation for nonlinear stabilization is when the
linearized system has uncontrollable modes on imaginary axis with the rest of modes stable. This is
so call... | bifurcations;linear controllability observability;bifurcation stabilization;projection method;nonlinear systems |
309133 | Locating Corruptions in a Replicated File in a Distributed Environment. | When a data file is replicated at more than one site, it is of interest to detect corruption by comparing the multiple copies. In order to reduce the amount of messaging for large files, techniques based on page signatures and combined signatures have been explored. However, for 3 or more sites, the known methods assum... | Introduction
When a data file is replicated at one or more sites in a distributed computer net-
work, it is of interest to discover corruptions in the file copies by making comparison
among the multiple physical copies of the file. Since a data file is typically large,
it is inefficient to transmit the entire file to a... | performance analysis;message transmission;signatures;file comparison;coding theory;fault tolerance;replicated file |
309181 | A Variable Metric Proximal Point Algorithm for Monotone Operators. | The proximal point algorithm (PPA) is a method for solving inclusions of the form $0\in T(z)$, where T is a monotone operator on a Hilbert space. The algorithm is one of the most powerful and versatile solution techniques for solving variational inequalities, convex programs, and convex-concave mini-max problems. It po... | Introduction
The Proximal Point Algorithm (PPA) is one of the most powerful and versatile solution
techniques for problems of convex programming and mini-max convex-concave program-
ming. It possesses a robust convergence theory for very general problem classes in finite-
and infinite-dimensions (e.g. see [11, 16, 21, ... | variable metric;global convergence;maximal monotone operator;proximal point methods;convergence rates |
309228 | Convergence of a Class of Inexact Interior-Point Algorithms for Linear Programs. | We present a convergence analysis for a class of inexact infeasible-interior-point methods for solving linear programs. The main feature of inexact methods is that the linear systems defining the search direction at each interior-point iteration need not be solved to high accuracy. More precisely, we allow that these l... | Introduction
Since the publication [6] of Karmarkar's original interior-point algorithm for linear programs, numerous
variants of the method have been developed; see, e.g., Kojima, Mizuno, and Yoshise [8],
Megiddo [13], Monteiro and Adler [17], and Tanabe [21]. Especially interesting is the algorithm by
Kojima, Megiddo... | infeasible-interior-point method;convergence;linear program;residual;inexact search direction;linear system |
309238 | Primal-Dual Affine-Scaling Algorithms Fail for Semidefinite Programming. | In this paper, we give an example of a semidefinite programming problem in which primal-dual affine-scaling algorithms using the HRVW/KSH/M, MT, and AHO directions fail. We prove that each of these algorithms can generate a sequence converging to a non-optimal solution and that, for the AHO direction, even its associat... | INTRODUCTION
We consider the standard form semidefinite programming (SDP) problem:
minimize C . X
subject to A i .
and its dual:
subject to Z
where C, X, A i belong to the space S(n) of n - n real symmetric matrices, the operator
. denotes the standard inner product in S(n), i.e., C . X := tr(CX
means that X is positiv... | affine-scaling algorithm;global convergence;primal-dual interior-point method;semidefinite programming |
309241 | Probabilistic Analysis of An Infeasible-Interior-Point Algorithm for Linear Programming. | We consider an infeasible-interior-point algorithm, endowed with a finite termination scheme, applied to random linear programs generated according to a model of Todd. Such problems have degenerate optimal solutions, and possess no feasible starting point. We use no information regarding an optimal solution in the init... | Introduction
A number of recent papers have attempted to analyze the probabilistic behavior of interior
point algorithms for linear programming. Ye (1994) showed that a variety of algorithms,
endowed with the finite termination scheme of Ye (1992) (see also Mehrotra and Ye 1993),
obtain an exact optimal solution with "... | infeasible-interior-point algorithm;linear programming;average-case behavior |
309247 | Solutions to Affine Generalized Equations Using Proximal Mappings. | The normal map has proven to be a powerful tool for solving generalized equations of the form: find z ε C, with 0 ε F(z) a convex set and NC(z) is the normal cone to C at z. In this paper, we use the T-map, a generalization of the normal map, to solve equations of the more general form: find z ε dom(T), ... | Introduction
This paper is concerned with solving generalized equations [20, 21] of the form
where T is a maximal monotone multifunction from IR n into IR n and F is a continuously differentiable
function from an open
set\Omega oe dom(T ) into IR n . We recall that a monotone multifunction T
is a point to set mapping s... | normal map;homotopy;generalized equations;piecewise affine |
309500 | Similarity-Based Models of Word Cooccurrence Probabilities. | In many applications of natural language processing (NLP) it is necessary to determine the likelihood of a given word combination. For example, a speech recognizer may need to determine which of the two word combinations eat a peach and eat a beach is more likely. Statistical NLP methods determine the likelihood of a w... | Introduction
Data sparseness is an inherent problem in statistical methods for natural language
processing. Such methods use statistics on the relative frequencies of configurations
of elements in a training corpus to learn how to evaluate alternative analyses or
interpretations of new samples of text or speech. The mo... | sense disambiguation;statistical language modeling |
309503 | A Winnow-Based Approach to Context-Sensitive Spelling Correction. | A large class of machine-learning problems in natural language require the characterization of linguistic context. Two characteristic properties of such problems are that their feature space is of very high dimensionality, and their target concepts depend on only a small subset of the features in the space. Under such ... | Introduction
A large class of machine-learning problems in natural language require the characterization
of linguistic context. Such problems include lexical disambiguation tasks
such as part-of-speech tagging and word-sense disambiguation; grammatical disambiguation
tasks such as prepositional-phrase attachment; and d... | winnow;context-sensitive spelling correction;bayesian classifiers;multiplicative weight-update algorithms |
309505 | Learning to Parse Natural Language with Maximum Entropy Models. | This paper presents a machine learning system for parsing natural language that learns from manually parsed example sentences, and parses unseen data at state-of-the-art accuracies. Its machine learning technology, based on the maximum entropy framework, is highly reusable and not specific to the parsing problem, while... | Introduction
The task of a natural language parser is to take a sentence as input and return a
syntactic representation that corresponds to the likely semantic interpretation of
the sentence. For example, some parsers, given the sentence
I buy cars with tires
would return a parse tree in the format:
I
buy NP
cars PP
wi... | parsing;natural language processing;maximum entropy models |
309594 | Value of Information in Capacitated Supply Chains. | We incorporate information flow between a supplier and a retailer in a two-echelon model that captures the capacitated setting of a typical supply chain. We consider three situations: (1) a traditional model where there is no information to the supplier prior to a demand to him except for past data; (2) the supplier kn... | Introduction
The industrial supplier-customer relations have undergone radical changes in recent years
as the philosophy behind managing manufacturing systems continues to be influenced by
several Japanese manufacturing practices. As more organizations realize that successful in-house
implementation of Just-In-Time alo... | Infinitesimal Perturbation Analysis;Capacitated Production-Inventory Model;information sharing;S Policy;optimal policies |
309690 | Minimal Decomposition of Model-Based Invariants. | Model-based invariants are relations between model parameters and image measurements, which are independent of the imaging parameters. Such relations are true for all images of the model. Here we describe an algorithm which, given L independent model-based polynomial invariants describing some shape, will provide a lin... | Introduction
An image provides us with relations between 3 different
kind of parameters: image measurements,
shape parameters, and imaging parameters (e.g.,
camera parameters). Here we restrict ourselves to
the domain of multiple points in multiple frames,
where the image measurements are 2D point co-
ordinates, and th... | model-based invariants;universal invariants;projective reconstruction |
310631 | An Experimental Study of Projective Structure From Motion. | AbstractWe describe an essentially algorithm-independent experimental comparison of projective versus Euclidean reconstruction. The Euclidean approach is as accurate as the projective one, even with significant calibration error and for the pure projective structure. Projective optimization has less of a local-minima p... | Introduction
The projective approach to structure from motion (SFM) was introduced
originally to avoid the difficulty of calibrating cameras precisely [1, 2]. Whereas
standard Euclidean SFM reconstructs a Euclidean 3D model of the scene
assuming a known camera calibration, projective SFM reconstructs the
projective str... | structure from motion;multiframe structure from motion;experimental verification;calibration;optimization;local minima;levenberg-marquardt;projective geometry |
310690 | Improving Service by Informing Customers About Anticipated Delays. | This paper investigates the effect upon performance in a service system, such as a telephone call center, of giving waiting customers state information. In particular, the paper studies two M/M/s/r queueing models with balking and reneging. For simplicity, it is assumed that each customer is willing to wait a fixed tim... | Introduction
[sec1] In this paper we investigate alternative ways to manage a service system. We have in
mind a telephone call center staffed by a group of operators, but there are other possible appli-
cations, e.g., internet access. We introduce birth-and-death (BD) stochastic process models that
can be used to demon... | Birth-and-Death Processes;balking;reneging;Telephone Call Centers;abandonments;service systems;Communicating Anticipated Delays;retrials |
311278 | A feedback based rate control algorithm for multicast transmitted video conferencing. | This paper presents a feedback based rate control algorithm for video conferencing on the Internet. This algorithm adaptively controls the transmission rate of a video stream, which is being multicast to a heterogeneous group of receivers. The fact that the sender is transmitting a single video stream to many receivers... | Introduction
The Internet has evolved from being heavily data oriented, to providing a whole range of services
including voice, video telephone and video conferencing. In addition to these different traffic types, the
resources in the Internet are very heterogeneous. From the end user's perspective, this heterogeneity
... | video conferencing;video multicasting;rate control;adaptive applications;VIC;RTP |
311896 | Staggered Consistent Checkpointing. | AbstractA consistent checkpointing algorithm saves a consistent view of a distributed application's state on stable storage. The traditional consistent checkpointing algorithms require different processes to save their state at about the same time. This causes contention for the stable storage, potentially resulting in... | Introduction
Applications executed on a large number of processors, either in a distributed environment,
or on multicomputers such as nCube, are subject to processor failures. Consistent check-pointing
is a commonly used technique to prevent complete loss of computation upon a
failure [1, 2, 4, 5, 8, 11, 13, 17]. A con... | consistent recovery line;stable storage contention;rollback recovery;fault tolerance;staggered checkpoints |
312175 | Fast Estimation of Diameter and Shortest Paths (Without Matrix Multiplication). | In the recent past, there has been considerable progress in devising algorithms for the all-pairs shortest paths (APSP) problem running in time significantly smaller than the obvious time bound of O(n3). Unfortunately, all the new algorithms are based on fast matrix multiplication algorithms that are notoriously imprac... | Introduction
Consider the problem of computing all-pairs shortest
paths (APSP) in an unweighted, undirected graph G
with n vertices and m edges. The recent work of Alon,
Galil, and Margalit [AGM91], Alon, Galil, Margalit, and
Naor [AGMN92], and Seidel [Sei92] has led to dramatic
progress in devising fast algorithms for... | shortest paths;diameter;matrix multiplication |
312209 | Buckets, Heaps, Lists, and Monotone Priority Queues. | We introduce the heap-on-top (hot) priority queue data structure that combines the multilevel bucket data structure of Denardo and Fox with a heap. Our data structure has superior operation bounds than either structure taken alone. We use the new data structure to obtain an improved bound for Dijkstra's shortest path... | Introduction
A priority queue is a data structure that maintains
a set of elements and supports operations insert,
decrease-key, and extract-min. Priority queues are
fundamental data structures with many applications.
Typical applications include graph algorithms (e.g. [14])
and event simulation (e.g. [5]).
An importan... | priority queues;data structures;shortest paths |
312215 | Local Labeling and Resource Allocation Using Preprocessing. | This paper studies the power of nonrestricted preprocessing on a communication graph G, in a synchronous, reliable system. In our scenario, arbitrary preprocessing can be performed on G, after which a sequence of labeling problems has to be solved on different subgraphs of G. We suggest a preprocessing that produces an... | Introduction
. The time required to perform certain computations in message-passing
systems depends, in many cases, on the locality of information, i.e., the distance
to which information should be forwarded. Clearly, within t communication
rounds, a processor can get information only from processors located within dis... | orientation;locality;response time;preprocessing;resource allocation;labeling |
312218 | Space-efficient Routing Tables for Almost All Networks and the Incompressibility Method. | We use the incompressibility method based on Kolmogorov complexity to determine the total number of bits of routing information for almost all network topologies. In most models for routing, for almost all labeled graphs, $\Theta (n^2)$ bits are necessary and sufficient for shortest path routing. By "almost all graphs"... | Introduction
. In very large communication networks like the global telephone
network or the internet connecting the worlds computers, the message volume
being routed creates bottlenecks degrading performance. We analyze a tiny part of
this issue by determining the optimal space to represent routing schemes in communic... | kolmogorov complexity;compact routing tables;average-case complexity;incompressibility method;space complexity;random graphs;routing algorithms;computer networks |
312404 | Pontryagin Maximum Principle for Optimal Control of Variational Inequalities. | In this paper we investigate optimal control problems governed by variational inequalities. We present a method for deriving optimality conditions in the form of Pontryagin's principle. The main tools used are the Ekeland's variational principle combined with penalization and spike variation techniques. | Introduction
. The purpose of this paper is to present a method for deriving a Pontryagin type
maximum principle as a first order necessary condition of optimal controls for problems governed by
variational inequalities. We allow various kinds of constraints to be imposed on the state. To be more
precise, we consider t... | optimal control;pontryagin principle;variational inequalities |
312456 | Fast Algorithms for Periodic Spline Wavelets on Sparse Grids. | We consider Boolean sums of univariate interpolation operators which define multivariate jth order blending interpolation operators on sparse grids. Sample spaces are defined as range of the blending operators. Sample and wavelet spaces have significantly lower dimension and good approximation order for certain functio... | Introduction
. Wavelet analysis has evolved in the last few years as a powerful
method in numerical analysis and signal processing. An important question is the
development of efficient algorithms for multivariate wavelet transforms. The classical
approach for the construction of bivariate wavelets from given univariat... | sparse grids;multivariate periodic interpolation;wavelets;splines;boolean sums |
312552 | The Incomplete Factorization Multigraph Algorithm. | We present a new family of multigraph algorithms, ILU-MG, based upon an incomplete sparse matrix factorization using a particular ordering and allowing a limited amount of fill-in. While much of the motivation for multigraph comes from multigrid ideas, ILU-MG is distinctly different from algebraic multilevel methods. T... | Introduction
. In this paper, we present a new family of multigraph algo-
rithms, ILU-MG, based upon an incomplete sparse matrix factorization using a carefully
designed ordering and allowing a limited amount of fill-in. While in this paper we
focus primarily on systems of linear equations arising from discretizations ... | algebraic multigrid;incomplete LU factorization;hierarchical basis |
312991 | The Discrete Cosine Transform. | Each discrete cosine transform (DCT) uses $N$ real basis vectors whose components are cosines. In the DCT-4, for example, the $j$th component of $\boldv_k$ is $\cos (j These basis vectors are orthogonal and the transform is extremely useful in image processing. If the vector $\boldx$ gives the intensities along a row o... | Introduction
Just as the Fourier series is the starting point in transforming and analyzing periodic func-
tions, the basic step for vectors is the Discrete Fourier Transform (DFT). It maps the "time
domain" to the "frequency domain." A vector with N components is written as a combination
of N special basis vectors v k... | cosine transform;orthogonality;signal processing |
314063 | Ranking Strategies for Navigation Based Query Formulation. | Navigating through a hypermedia retrieval system bears the problem of selecting an item from a large number of options available to continue the trajectory. Ranking these options according to some criterion is a method to ease the task of navigation. A number of ranking strategies have already been proposed. This paper... | Introduction
In some ways, the introduction of mass storage devices like CD-ROM has been a mixed blessing.
True, we can offer large amounts of information, be it sound, video or text. However, the task of
finding the right information has become increasingly difficult. Although indexing the information
somewhat reduces... | hypermedia;search support;query formulation;information retrieval |
314517 | A decision-theoretic approach to database selection in networked IR. | In networked IR, a client submits a query to a broker, which is in contact with a large number of databases. In order to yield a maximum number of documents at minimum cost, the broker has to make estimates about the retrieval cost of each database, and then decide for each database whether or not to use it for the cur... | Introduction
Networked information retrieval (NIR) is a new research area challenged by the rapid growth of
the Internet and the widespread use of IR servers like e.g. WAIS or systems supporting the Z39.50
protocol (see e.g. [Kahle et al. 93]). Besides classical applications like bibliographies, more recently
digital l... | resource discovery;probabilistic retrieval;probability ranking principle;networked retrieval |
314522 | Interface and data architecture for query preview in networked information systems. | There are numerous problems associated with formulating queries on networked information systems. These include increased data volume and complexity, accompanied by slow network access. This article proposes a new approach to a network query user interfaces that consists of two phases: query preview and query refinemen... | INTRODUCTION
The exploration of networked information resources becomes increasingly difficult as the
volume of data grows. We identified at least the following problems of information
retrieval in networked environments:
. Data Volume: The amount of data available is rapidly increasing. For example, some
sensor data i... | graphical user interface;direct manipulation;science data;dynamic query;query preview;EOSDIS;query refinement |
316184 | type signatures for legacy Fortran subroutines. | We are currently developing a methodological framework for reverse engineering Fortran77 programs used by Electricité de France, in which the first step is the construction of an algebraic specification which faithfully represents the Fortran code. To construct this specification, we must decide on a coherent se... | Introduction
Much of the software currently in use at Electricit'e de France
(EDF), though giving entirely satisfactory results, was written
15 or 20 years ago. The replacement of these existing
systems by new software re-developed from scratch can
be expensive, risky and time-consuming. As a response to
this problem, ... | array region;dynamic alias;fortran;reverse engineering;alias analysis |
316259 | Multicategory Classification by Support Vector Machines. | We examine the problem of how to discriminate between objects of three or more classes. Specifically, we investigate how two-class discrimination methods can be extended to the multiclass case. We show how the linear programming (LP) approaches based on the work of Mangasarian and quadratic programming (QP) approaches ... | Introduction
We investigate the problem of discriminating large real-world datasets with
more than two classes. Given examples of points known to come from k >
classes, we construct a function to discriminate between the classes. The
goal is to select a function that will e#ciently and correctly classify future
points.... | support vector machines;data mining;classification;linear programming;machine learning |
316278 | Stabilized Sequential Quadratic Programming. | Recently, Wright proposed a stabilized sequential quadratic programming algorithm for inequality constrained optimization. Assuming the Mangasarian-Fromovitz constraint qualification and the existence of a strictly positive multiplier (but possibly dependent constraint gradients), he proved a local quadratic convergenc... | Introduction
.
Let us consider the following inequality constrained optimization problem:
minimize f(z) subject to c(z) - 0; z 2 R n ; (1)
where f is real-valued and c : R n the Lagrangian L is defined
by
denote the current approximation to a local minimizer z and an associated
multiplier - for (1). In the sequenti... | superlinear convergence;error estimation;stabilized SQP;sequential quadratic programming;degenerate optimization;quadratic convergence |
316283 | Service Combinators for Web Computing. | AbstractThe World Wide Web is rich in content and services, but access to these resources must be obtained mostly through manual browsers. We would like to be able to write programs that reproduce human browsing behavior, including reactions to slow transmission-rates and failures on many simultaneous links. We thus in... | Introduction
The World-Wide Web [1] is a uniform, highly interconnected collection of computational
resources, and as such it can be considered as forming a single global computer.
But, what kind of computer is the Web, exactly? And what kind of languages are
required for programming such a computer? Before approaching... | World Wide Web;programming languages;wide area computation |
316287 | A Domain-Specific Language for Regular Sets of Strings and Trees. | AbstractWe propose a new high-level programming notation, called FIDO, that we have designed to concisely express regular sets of strings or trees. In particular, it can be viewed as a domain-specific language for the expression of finite-state automata on large alphabets (of sometimes astronomical size). FIDO is based... | Introduction
Finite-state problems are everywhere, embedded in
many layers of software systems, but are often difficult
to extract and solve computationally. This
basic observation is the motivation for the work presented
in this paper.
Recent research by us and our colleagues has exploited
the Monadic Second-Order Log... | trees;regular sets;strings;logic;domain-specific languages |
316355 | An Interior-Point Algorithm for Nonconvex Nonlinear Programming. | The paper describes an interior-point algorithm for nonconvex nonlinear programming which is a direct extension of interior-point methods for linear and quadratic programming. Major modifications include a merit function and an altered search direction to ensure that a descent direction for the merit function is obtain... | INTRODUCTION
In this paper, we describe modifications that we used to convert the quadratic programming
(QP) solver LOQO into a general nonconvex nonlinear programming solver (of the
same name). As a code for quadratic programming, LOQO implements an interior-point
method. The complete details of the QP implementation ... | nonconvex optimization;nonlinear programming;interior-point methods |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.