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597050
Supporting Content-Based Retrieval in Large Image Database Systems.
In this paper, we investigate approaches to supporting effective and efficient retrieval of image data based on content. We first introduce an effective block-oriented image decomposition structure which can be used to represent image content in image database systems. We then discuss the application of this image data...
Introduction Content-based image retrieval has been proposed to allow retrievals to be performed on the basis of a variety of aspects of image content [1, 5, 15, 10, 6, 2, 18]. In this context, a challenging problem arises with many image databases, within which queries are posed via visual or pictorial examples. We te...
wavelet transforms;image representation;content-based image retrieval;texture;image decomposition;image database systems
597056
Concepts for Resource Reservation in Advance.
Resource management offers Quality-of-Service reliability for time-critical continuous-media applications. Currently, existing resource management systems in the Internet and ATM domain only provide means to reserve resources starting with the reservation attempt and lasting for an unspecified duration. However, for se...
Introduction Computer systems used for continuous media processing must cope with streams having data rates of several Mbits/s and must provide timely processing guarantees. For instance, an end-system shall synchronize audio and video streams up to a granularity of about 80 ms [16]. Since available system resources ar...
resource reservation;multimedia;quality of service;resource management;advance reservation
597100
Handling Updates and Crashes in VoD Systems.
Though there have been several recent efforts to develop disk based video servers, these approaches have all ignored the topic of updates and disk server crashes. In this paper, we present a priority based model for building video servers that handle two classes of events: user events that could include enter, play, pa...
Introduction Over the last few years, there has been a tremendous drop in digitization costs, accompanied by a concomitant drop in prices of secondary and tertiary storage facilities, and advances in sophisticated compression technology. These three advances, amongst others, have caused a great increase in the quality ...
constraints;priority and optimal handling;video server;updates;disk crashes
597142
Tune Retrieval in the Multimedia Library.
Musical scores are traditionally retrieved by title, composer or subject classification. Just as multimedia computer systems increase the range of opportunities available for presenting musical information, so they also offer new ways of posing musically-oriented queries. This paper shows how scores can be retrieved fr...
Introduction Music librarians are often asked to find a piece of music based on a few hummed or whistled notes. The magnitude of this task may be judged by the fact that the Library of Congress holds over six million pieces of sheet music-not including tens of thousands of operatic scores and other major works (Goodrum...
acoustic interfaces;relevance ranking;melody recall;music retrieval
597143
QoS Management in Educational Digital Library Environments.
Advances in multimedia computing technologies offer new approaches to the support of computer-assisted education and training within many application domains. Novel interactive presentation tools can be built to enhance traditional teaching methods with more active learning. Since a variety of user expectations are pos...
Introduction Currently available computer hardware and devices can support the processing of data in various media, including video, audio, animation, and still images. Many multimedia standards for software and hardware are already in place for uniform handling of multimedia data. These technologies have made it possi...
digital libraries;quality of service QoS;synchronization;multimedia
597195
Optimal Scheduling for Parallel CBR Video Servers.
Parallel video servers are necessary for large-scale video-on-demand and other multimedia systems. This paper addresses the scheduling problem of parallel video servers. We discuss scheduling requirements of constant bit rate (CBR) video streams. Optimal algorithms are presented for conflict-free scheduling, delay mini...
Introduction There is an increasing demand on capacity of video servers in large-scale video-on- demand systems [9, 3]. Parallel video servers become inevitable to provide large capacity required by the system that can service thousands of concurrent clients. There are two major types of parallel video servers: shared ...
Quality of Service QoS;video servers;video streams;constant bit rate CBR;large-scale VoD;conflict-free scheduling
597201
Audio Partitioning and Transcription for Broadcast Data Indexation.
This work addresses automatic transcription of television and radio broadcasts in multiple languages. Transcription of such types of data is a major step in developing automatic tools for indexation and retrieval of the vast amounts of information generated on a daily basis. Radio and television broadcasts consist of a...
Introduction With the rapid expansion of different media sources for information dissemination, there is a need for automatic processing of the data. For the most part todays methods for transcription and indexation are manual, with humans reading, listening and watching, annotating topics and selecting items of intere...
audio segmentation;speech recognition;audio indexation
597208
Determination Based on Video and Audio Features.
Determining automatically what constitutes a scene in a video is a challenging task, particularly since there is no precise definition of the term scene. It is left to the individual to set attributes shared by consecutive shots which group them into scenes. Certain basic attributes such as dialogs, settings and contin...
Introduction Depending on their length, shots are either the letters or words of video productions. Hence, they contain little semantic information: information in the image track can often be reduced to a simple keyframe or panorama [25], while in the audio track it is usually either incomplete (like a part of a dialo...
shot clustering;content-based video analysis;audio-based video analysis;scene detection;dialog detection
597241
Heterogeneous CPU Services Using Differentiated Admission Control.
We present an adaptive rate-controlled scheduler for heterogeneous applications running on general purpose computers. Our scheduler can effectively support diverse application requirements. It employs uniform rate-based sharing. Application heterogeneity is satisfied by partitioning CPU capacity into service classes, e...
Introduction Emerging continuous media (CM) applications have well defined quality of service (QoS) constraints. These applications have stringent resource requirements and can benefit from non-interference. It is not possible to run them in a closed or embedded system environment [11]. Instead, many will continue to r...
priority inversion;firewall protection;CPU scheduling;multimedia operating system;rate-based sharing;admission control
597244
Scheduling and Optimization of the Delivery of Multimedia Streams Using Query Scripts.
New techniques are necessary to satisfy the high bandwidth requirement and temporal relationships of multimedia data streams in a network environment. Clients can experience gaps between the multimedia data streams during presentations as the multimedia server services multiple clients. This variable delay occurs betwe...
Introduction Multimedia information systems require new data modeling and delivery capabilities to specify and guarantee temporal relationships between streams [7]. These capabilities are more critical in distributed computing systems due to multimedia data's high resource require- ments. In this paper we propose the u...
query script;optimization;simulation;delivery scheduling;multimedia streams
597249
Fundamentals of Scheduling and Performance of Video Tape Libraries.
Robotic tape libraries are popular for applications with very high storage requirements, such as video servers. Here, we study the throughput of a tape library system, we design a new scheduling algorithm, the so-called Relief, and compare it against some older/straightforward ones, like FCFS, Maximum Queue Length (MQL...
Introduction Even though secondary storage devices (based on magnetic disks) have become cheaper and increased their storage capacity at remarkable rates, they still cannot satisfy economically the storage requirements of video-based databases for many demanding applications, such as video-on-demand, digital libraries,...
scheduling algorithms;video tape libraries;performance
597252
Dealing with Uncertain Durations in Synchronized Multimedia Presentations.
In this paper, we discuss the effect of the uncertainty in the duration of some multimedia objects on the quality of the presentation of multimedia scenarios. This uncertainty can be due to external factors such as the access delay over internet or the user interaction. An uncertain duration is often followed by a peri...
Introduction A multimedia presentation is a set of media objects rendered over a pre-established temporal scenario. The different objects are presented according to predefined durations set at the authoring stage (Kim, 1995). This scenario is contained in a multimedia document defined by an author and remotely accessed...
multimedia;uncertain durations;dynamic formatting;scheduling;synchronization
597254
A Sequence-Based Object-Oriented Model for Video Databases.
Structuration, annotation and composition are amidst the most crucial modeling issues that video editing and querying in the context of a database entail. In this paper, we propose a sequence-based, object-oriented data model that addresses them in an unified, yet orthogonal way. Thanks to this orthogonality, the inter...
Introduction For a long time, videos were managed by specific environments due to their huge size and demanding hardware requirements. Improvements in data compression (such as MPEG-2), continuously increasing network transfer rates and processing capacity, and advances in operating systems, now allow conventional comp...
temporal databases;object-oriented databases;video databases;ODMG
597338
Coordinating electronic commerce activities in MANIFOLD.
Modern electronic commerce environments are heavily web-based and involve issues such as distributed execution, multiuser interactive access or interface with and use of middleware platforms. Thus, their components exhibit the properties of communication, cooperation and coordination as in CSCW, groupware or workfl...
Introduction Modelling of activities within an information system or between different information systems has become a complex task. Performing these activities (often known as groupware, workflow, electronic commerce and enterprize reengineering) is often done in conjunction with computer-based cooperative environmen...
coordination models and languages;web-based applications;electronic commerce
597926
Model-based analysis of configuration vulnerabilities.
Vulnerability analysis is concerned with the problem of identifying weaknesses in computer systems that can be exploited to compromise their security. In this paper we describe a new approach to vulnerability analysis based on model checking. Our approach involves: Formal specification of desired security properties. ...
Introduction System configuration vulnerabilities can be traced back to classic problems in software engineer- ing, such as unexpected interactions between different system modules and violation of hidden assumptions. For instance, consider a vulnerability that existed in early versions of the fingerd service. In servi...
model checking;automated verification;intrusion detection;computer security;vulnerability analysis
597944
Explicit Solutions for Variational Problems in the Quadrant.
We study a variational problem (VP) that is related to semimartingale reflecting Brownian motions (SRBMs). Specifically, this VP appears in the large deviations analysis of the stationary distribution of SRBMs in the d-dimensional orthant Rd+. When d=2, we provide an explicit analytical solution to the VP. This ...
Introduction Semimartingale reflecting Brownian motions (SRBMs) in the orthant have been proposed as approximate models of open queueing networks (see e.g, Harrison and Nguyen [16]). Such di#usion processes were first introduced in Harrison and Reiman [17]. Since then, there have been two primary lines of active resear...
skorohod problems;large deviations;reflecting Brownian motions;variational problems;queueing networks
597978
Fluid approximations for a processor-sharing queue.
In this paper a fluid approximation, also known as a functional strong law of large numbers (FSLLN) for a GI/G/1 queue under a processor-sharing service discipline is established and its properties are analysed. The fluid limit depends on the arrival rate, the service time distribution of the initial customers, and...
Introduction Consider a single server queue with n new jobs residing in the queue at time 0, and a renewal stream of arrivals, rate -. The service times for these jobs are described by a sequence of independent identically distributed (i.i.d.) nonnegative random variables, with processing rate - and with processing tim...
functional strong law of large numbers;processor-sharing discipline;fluid approximation;GI/G/1 queue
597998
Heavy traffic analysis of controlled multiplexing systems.
The paper develops the mathematics of the heavy traffic approach to the control and optimal control problem for multiplexing systems, where there are many mutually independent sources which feed into a single channel via a multiplexer (or of networks composed of such subsystems). Due to the widely varying bit rates...
Introduction The paper develops the mathematics of the heavy traffic approach to the control and optimal control problem for multiplexing systems. There are many mutually independent sources which feed into a single channel via a multiplexer or networks of such systems. Since the process of cell generation by each sour...
multiplexing systems;ergodic cost problem;controlled multiplexing;heavy traffic
598060
Moderate deviations for queues in critical loading.
We establish logarithmic asymptotics of moderate deviations for queue-length and waiting-time processes in single server queues and open queueing networks in critical loading. Our results complement earlier diffusion approximation results.
Introduction This paper complements the classical results on heavy-traffic approximation for queues in Kingman [7], Prohorov [12], Iglehart and Whitt [5], Borovkov [1], and Reiman [19] by studying some related large-deviation asymptotics. In a standard set-up, one considers a sequence of GI=GI=1 queues indexed by n wit...
queues;large deviation principle;heavy traffic
598068
Window flow control in FIFO networks with cross traffic.
We focus on window flow control as used in packet-switched communication networks. The approach consists in studying the stability of a system where each node on the path followed by the packets of the controlled connection is modeled by a FIFO queue of infinite capacity which receives in addition some cross traffi...
Introduction Flow control mechanisms are used in packet-switched communication networks to prevent routers from congestion, by regulating the input traffic generated by the users. The most widely used mechanism is the window flow control, like that of TCP (Transmission Control Protocol) over the Internet [7]. This mech...
multiclass networks;stationary ergodic point processes;window flow control;+-linear system;stability;TCP
598082
Subexponential loss rates in a GI/GI/1 queue with applications.
Consider a single server queue with i.i.d. arrival and service processes, \{A,\ A_n,n\geq 0\} and \{C,\ C_n,n\geq 0\}, respectively, and a finite buffer B. The queue content process \{Q^B_n,\ n\geq 0\} is recursively defined as Q^B_{n+1}=\min((Q^B_n+A_{n+1}-C_{n+1})^+,B), q^+=\max(0,q). When \mathbb{E}(A-C)<0, and...
Introduction An increasing body of literature on statistical data analysis has demonstrated the presence of long-tailed/subexponential characteristics in communication network traffic streams. Early discoveries on the long-tailed nature of Ethernet traffic was reported in [32]. Long-tailed characteristics of the scene ...
long-range dependency;finite buffer queue;M/G/infty process;long-tailed traffic models;fluid flow queue;network multiplexer;subexponential distributions
598167
Stability of Fluid Networks with Proportional Routing.
In this paper we investigate the stability of a class of two-station multiclass fluid networks with proportional routing. We obtain explicit necessary and sufficient conditions for the global stability of such networks. By virtue of a stability theorem of Dai [14] , these results also give sufficient conditions for the...
Introduction In the last decade, there has been an explosion of research and interest in multiclass queueing networks and their uid counterparts. Multiclass queueing networks are stochastic processing networks which are often more suitable than traditional queueing systems for modeling highly complex manufacturing, com...
acyclic routing;push start;multiclass queueing network;fluid model;virtual station;stability
598174
Existence Condition for the Diffusion Approximations of Multiclass Priority Queueing Networks.
In this paper, we extend the work of Chen and Zhang [12] and establish a new sufficient condition for the existence of the (conventional) diffusion approximation for multiclass queueing networks under priority service disciplines. This sufficient condition relates to the weak stability of the fluid networks and the sta...
Introduction We consider a general multiclass queueing network under a preemptive resume priority service discipline. The network consists of J single server (service) stations, each with an infinite buffer (waiting room). There are K ( J) classes of jobs, indexed by K. While each station may serve more than one class ...
priority service discipline;multiclass queueing network;heavy traffic;semimartingale reflecting Brownian motion;diffusion approximation;fluid approximation
598395
New multivariate product density estimators.
Let X be an Rd-valued random variable with unknown density f. Let X1 ...., Xn be i.i.d, random variables drawn from f. The objective is to estimate f(x), where We study the pointwise convergence of two new density estimates, the Hilbert product kernel estimate d!/n i=1nj=1d1/2log n|xjXij|, where and the Hilbert k-neare...
Introduction . The objective of this note is to study two new multivariate density estimates that avoid the messy problem of smoothing factor selection (in one case, at least), are invariant to a#ne transformations of the coordinates, and provide easy means to jointly estimate all 2 d marginal densities of a density f ...
saks rarity theorem;nearest neighbor estimate;Jessen-Marcinkiewicz-Zygmund theorem;convergence;kernel estimate;bandwidth selection;nonparametric estimation;density estimation
598407
Coherence-Enhancing Diffusion Filtering.
The completion of interrupted lines or the enhancement of flow-like structures is a challenging task in computer vision, human vision, and image processing. We address this problem by presenting a multiscale method in which a nonlinear diffusion filter is steered by the so-called interest operator (second-moment matrix...
Introduction Oriented flow-like structures arise in many computer vision and image processing problems: Within the field of texture analysis they appear for instance in the automatic grading of fabrics or wood surfaces, but they are also of importance for fingerprint analysis in forensic applications. They are present ...
scale-space;nonlinear diffusion;image enhancement;texture
598422
Hypothetical Temporal Reasoning in Databases.
In this paper we integrate a historyencoding based methodology for checking dynamic database integrity constraints into a situation-calculus based specification of relational database updates. By doing this, we are able to: (1) Answer queries about a whole hypothetical evolution of a database, without having to update ...
Introduction In (Reiter, 1995), as an application of his solution to the frame problem (Reiter, 1991), Ray Reiter proposed to specify the transaction based updates of a relational database by means of a particular kind of axioms written in the situation calculus (SC) (McCarthy et al., 1969). In (Bertossi et al., 1998) ...
dynamic integrity constraints;hypothetical reasoning;database dynamics;historical queries
598450
Euclidean Reconstruction and Reprojection Up to Subgroups.
The necessary and sufficient conditions for being able to estimate scene structure, motion and camera calibration from a sequence of images are very rarely satisfied in practice. What exactly can be estimated in sequences of practical importance, when such conditions are not satisfied? In this paper we give a complete ...
Introduction Reconstructing spatial properties of a scene from a number of images taken by an uncalibrated camera is a classical problem in computer vision. It is particularly important when the camera used to acquire the images is not available for calibration, as for instance in video post-processing, or when the cal...
reprojection;multilinear constraints;reconstruction ambiguity;camera self-calibration
598459
The Joy of Sampling.
A standard method for handling Bayesian models is to use Markov chain Monte Carlo methods to draw samples from the posterior. We demonstrate this method on two core problems in computer visionstructure from motion and colour constancy. These examples illustrate a samplers producing useful representations for very large...
Quite often in practice it is easy to come up with a function f proportional to the posterior. In this case, the posterior is f R f .u/ du but the integral-the normalizing constant-can be very difficult to compute (the best way to do it is to use a sampling method). An attractive feature of the MetropolisHastingsalgori...
colour constancy;structure from motion;Markov chain Monte Carlo
598491
Dense Features for Semi-Dense Stereo Correspondence.
We present a new feature based algorithm for stereo correspondence. Most of the previous feature based methods match sparse features like edge pixels, producing only sparse disparity maps. Our algorithm detects and matches dense features between the left and right images of a stereo pair, producing a semi-dense dispari...
Introduction Stereo correspondence is one of the oldest problems in computer vision, with numerous applications. Due to noise and image structure, establishing correspondence is an ambiguous task. The very first designers of stereo algorithms recognized this fact. A way to disambiguate the problem is to make additional...
adaptive threshold;stereo;visual correspondence;dense features
598537
A Multiphase Level Set Framework for Image Segmentation Using the Mumford and Shah Model.
We propose a new multiphase level set framework for image segmentation using the Mumford and Shah model, for piecewise constant and piecewise smooth optimal approximations. The proposed method is also a generalization of an active contour model without edges based 2-phase segmentation, developed by the authors earlier ...
partition problem of (Mumford and Shah 1989) for segmentation of images. For the implementation of the active contour model from (Chan and Vese 1999), (Chan and Vese 2001), the level set method of (Osher and Sethian 1988) was successfully used, together with a particular numerical approximation, which allowed to automa...
energy minimization;level sets;image segmentation;edge detection;active contours;curvature;denoising;multi-phase motion;PDE's
598632
Multistage Nonlinear Blind Interference Cancellation for DS-CDMA Systems.
In this paper we propose a multistage nonlinear blind interference cancellation (MS-NL-BIC) receiver for direct-sequence code-division multiple-access (DS-CDMA) systems. The receiver uses higher order statistics of the received baseband signal. Specifically, we use the second and fourth moments of the received signal t...
Introduction One of the driving forces of the next generation of wireless communications is the demand for higher data rates and higher capacity of wireless systems. Primary applications of higher data rates seem to be in the downlink direction (for example, typical internet data tra#c such as downloading of web pages)...
blind interference cancellation;successive interference cancellation;iterative refinement
598755
A Conceptual Model and Rule-Based Query Language for HTML.
Most documents available over the Web conform to the HTML specification. Such documents are hierarchically structured in nature. The existing data models for the Web either fail to capture the hierarchical structure within the documents or can only provide a very low level representation of such hierarchical structure....
Introduction Most documents available over the web conform to the HTML specication. They are intended to be human readable through a browser and thus are constructed following some common conventions and often exhibit some hierarchical structure. How to represent such documents at the conceptual level is an important i...
HTML query language;rule-based query language;fixpoint logical semantics;data model for HTML;conceptual modeling
598838
Bijective and General Arithmetic Codings for Pisot Toral Automorphisms.
Let T be an algebraic automorphism of {\Bbb T}^m having the following property: the characteristic polynomial of its matrix is irreducible over \Bbb Q, and a Pisot number is one of its roots. We define the mapping &phiv;t acting from the two-sided -compactum onto {\Bbb T}^m as follows: \varphi_t is a fundamental homo...
Introduction Let T be an algebraic automorphism of the torus T m given by a matrix M 2 GL(m;Z) with the following property: the characteristic polynomial for M is irreducible over Q , and a Pisot number > 1 is one of its roots (we recall that an algebraic integer is called a Pisot number if it is greater than 1 and al...
pisot automorphism;integral form;arithmetic coding;homoclinic point
599252
Interpolation models with multiple hyperparameters.
A traditional interpolation model is characterized by the choice of regularizer applied to the interpolant, and the choice of noise model. Typically, the regularizer has a single regularization constant , and the noise model has a single parameter . The ratio / alone is responsible for determining globally all these at...
Introduction In this paper our philosophy of generalization is as follows: the best generalization will be achieved by a Bayesian model that is well-matched to the problem and that is accurately implemented. The aim of obtaining the best generalization is thus subsumed under the aim of searching for good models. In thi...
convexity;regularizer;bayesian inference;neuronal spike;spline;regression
599262
Inference in model-based cluster analysis.
A new approach to cluster analysis has been introduced based on parsimonious geometric modelling of the within-group covariance matrices in a mixture of multivariate normal distributions, using hierarchical agglomeration and iterative relocation. It works well and is widely used via the MCLUST software available in S-P...
Introduction Banfield and Raftery (1993) - hereafter BR - building on work of Murtagh and Raftery (1984), introduced a new approach to cluster analysis based on a mixture of multivariate normal distributions, where the covariance matrices are modeled parsimoniously in a geometrically interpretable way. The general fini...
bayes factor;gaussian mixture;eigenvalue decomposition;gibbs sampler
599292
Bayesian MARS.
A Bayesian approach to multivariate adaptive regression spline (MARS) fitting (Friedman, 1991) is proposed. This takes the form of a probability distribution over the space of possible MARS models which is explored using reversible jump Markov chain Monte Carlo methods (Green, 1995). The generated sample of MARS models...
Introduction A common problem in statistics, and other disciplines, is to approximate adequately a function of several variables. In a statistical setting this is known as multiple regression and the task can be performed either parametrically by global modelling (e.g. linear regression), or nonparametrically (see belo...
multivariate adaptive regression splines;reversible jump Markov Chain Monte Carlo;bayesian methods;multiple regression
599361
Bayesian parameter estimation via variational methods.
We consider a logistic regression model with a Gaussian prior distribution over the parameters. We show that an accurate variational transformation can be used to obtain a closed form approximation to the posterior distribution of the parameters thereby yielding an approximate posterior predictive model. This approach ...
Introduction Bayesian methods have a number of virtues, particularly their uniform treatment of uncertainty at all levels of the modeling process. The formalism also allows ready incorporation of prior knowledge and the seamless combination of such knowledge with observed data (Bernardo & Smith 1994, Gelman 1995, Hecke...
variational methods;logistic regression;graphical models;incomplete data;belief networks;bayesian estimation
599401
Annealed importance sampling.
Simulated annealingmoving from a tractable distribution to a distribution of interest via a sequence of intermediate distributionshas traditionally been used as an inexact method of handling isolated modes in Markov chain samplers. Here, it is shown how one can use the Markov chain transitions for such an annealing seq...
Introduction In Bayesian statistics and statistical physics, expectations of various quantities with respect to complex distributions must often be computed. For simple distributions, we can estimate expectations by sample averages based on points drawn independently from the distribution of interest. This simple Monte...
tempered transitions;sequential importance sampling;estimation of normalizing constants;free energy computation
599407
Stable local computation with conditional Gaussian distributions.
This article describes a propagation scheme for Bayesian networks with conditional Gaussian distributions that does not have the numerical weaknesses of the scheme derived in Lauritzen (Journal of the American Statistical Association 87: 10981108, 1992).The propagation architecture is that of Lauritzen and Spiegelhalte...
Introduction Bayesian networks have developed into an important tool for building systems for decision support in environments characterized by uncertainty (Pearl 1988; Jensen 1996; Cowell et al. 1999). The exact computational algorithms that are most developed are concerned with networks involving discrete variables o...
propagation of evidence;bayesian networks;gaussian mixtures;artificial intelligence;probabilistic expert systems;CG distributions
599421
Parameter estimation for a deformable template model.
In recent years, a number of statistical models have been proposed for the purposes of high-level image analysis tasks such as object recognition. However, in general, these models remain hard to use in practice, partly as a result of their complexity, partly through lack of software. In this paper we concentrate on a ...
INTRODUCTION The use of high-level models in image analysis has increased in popularity during the last few years as the problem of interpretation and understanding of images has become more important. One specific task for which such models have been proposed is object recognition, locating objects in a scene and prov...
object recognition;Markov chain Monte Carlo;bayesian image analysis;deformable templates;parameter estimation;confocal microscopy
599447
Choice of wavelet smoothness, primary resolution and threshold in wavelet shrinkage.
This article introduces a fast cross-validation algorithm that performs wavelet shrinkage on data sets of arbitrary size and irregular design and also simultaneously selects good values of the primary resolution and number of vanishing moments.We demonstrate the utility of our method by suggesting alternative estimates...
Introduction Wavelet shrinkage is a technique for estimating curves in the presence of noise which is appealing because it is nearly minimax for a wide range of functions, computationally practical and spatially adaptive (see the seminal work of Donoho et al. (1995)). This paper assumes a familiarity with wavelets and ...
ethanol data;kovac-silverman algorithm;fast wavelet shrinkage updates;cross-validation
599448
Perfect simulation for correlated Poisson random variables conditioned to be positive.
In this paper we present a perfect simulation method for obtaining perfect samples from collections of correlated Poisson random variables conditioned to be positive. We show how to use this method to produce a perfect sample from a Boolean model conditioned to cover a set of points: in W.S. Kendall and E. Thnnes (Patt...
Introduction Markov chain Monte Carlo (McMC) provides the opportunity to carry out simulation-based statistical inference, by allowing one to sample approximately from a target distribution realised as the equilibrium of a Markov chain. The approximate nature of McMC arises because the output is subject to initializati...
Markov chain Monte Carlo;correlated Poisson random variables conditioned to be positive;conditional Boolean model;perfect simulation;extended state-space CFTP;dominated CFTP
599486
An Efficient Partial Order Reduction Algorithm with an Alternative Proviso Implementation.
This paper presents a partial order reduction algorithm called Twophase that generates a significantly reduced state space on a large class of practical protocols over alternative algorithms in its class. The reduced state-space generated by Twophase preserves all CTL&ast;-X assertions. Twophase achieves this reduction...
Introduction With the increasing scale of software and hardware systems and the corresponding increase in the number and complexity of concurrent protocols involved in their design, formal verification of concurrent protocols is an important practical need. Automatic verification of finite state systems based on explic...
explicit enumeration;partial order reductions;concurrent protocol verification;proviso;temporal logic;on-the-fly model-checking;in-stack checking
599488
An Improvement of McMillan''s Unfolding Algorithm.
McMillan has recently proposed a new technique to avoid the state explosion problem in the verification of systems modelled with finite-state Petri nets. The technique requires to construct a finite initial part of the unfolding of the net. McMillan's algorithm for this task may yield initial parts that are larger than...
Introduction In a seminal paper [10], McMillan has proposed a new technique to avoid the state explosion problem in the verification of systems modelled with finite-state Petri nets. The technique is based on the concept of net un- folding, a well known partial order semantics of Petri nets introduced in [12], and late...
partial-order semantics;petri nets;unfolding
599492
Logical fusion rules for merging structured news reports.
Structured text is a general concept that is implicit in a variety of approaches in handling information. Syntactically, an item of structured text is a number of grammatically simple phrases together with a semantic label for each phrase. Items of structured text may be nested within larger items of structured text. M...
Introduction Syntactically, an item of structured text is a data structure containing a number of grammatically simple phrases together with a semantic label for each phrase. The set of semantic labels in a structured text is meant to parameterize a stereotypical situation, and so a particular item of structured text i...
conflict resolution;merging information;logic-based fusion;heterogenous information;logic-based inconsistency management;structured text;semi-structured text;inconsistency handling
599497
Analysis and optimization of active databases.
We introduce a new formal semantics for active databases that relies on a transaction rewriting technique. A user-defined transaction, which is viewed here as a sequence of atomic database updates forming a semantic atomic unit, is translated by means of active rules into induced one(s). These transactions embody activ...
Introduction Active databases are based on rules that allow us to specify actions to be taken by the system automatically, when certain events occur and some conditions are met. It is widely recognized that these active rules provide a powerful mechanism for the management of several important database activities (e.g....
optimization;rule semantics;confluence;active databases;transaction equivalence
599526
Models and motion planning.
We study the complexity of the motion planning problem for a bounded-reach robot in the situation where the n obstacles in its workspace satisfy two of the realistic models proposed in the literature, namely unclutteredness and small simple-cover complexity. We show that the maximum complexity of the free space of a ro...
Introduction It is well known that the maximum complexity of the free space of a robot with f degrees of freedom moving in a scene consisting of n disjoint obstacles of constant complexity can be # n f ). Consequently, exact motion-planning algorithms often have a worst-case running time of at least the same order of m...
motion planning;free space complexity;input models
599532
On the autocorrelation structure of TCP traffic.
The statistical characteristics of network traffic--in particular the observation that it can exhibit long range dependence--have received considerable attention from the research community over the past few years. In addition, the recent claims that the TCP protocol can generate traffic with long range dependent behav...
Introduction The existence of non-degenerate correlation structures over a range of timescales in network tra-c has been observed in a variety of network environments, such as Ethernet tra-c [1], Networks tra-c [2], and World Wide Web tra-c [3]. There have been recently many research eorts to investigate various aspect...
long range dependence;network traffic characterization;TCP mechanisms
599552
A new wireless ad hoc multicast routing protocol.
An ad hoc network is a multi-hop wireless network of mobile nodes without the intervention of fixed infrastructure. Limited bandwidth and mobility require that ad hoc routing protocols be robust, simple, and energy conserving. This paper proposes a new ad hoc multicast routing protocol called neighbor-supporting multic...
Introduction An ad hoc network is a multi-hop wireless network formed by a collection of mobile nodes without the intervention of fixed infrastructure. Because an ad hoc network is infrastructure-less and self-organized, it is used to provide impromptu communication facilities in inhospitable environments. Typical appl...
ad hoc network;multicast routing;node locality
599555
A network infrastructure for IP mobility support in metropolitan areas.
The original design of the Internet and its underlying protocols did not anticipate users to be mobile. With the growing interest in supporting mobile users and mobile computing, a great deal of work is taking place to solve this problem. For a solution to be practical, it has to integrate easily with existing Internet...
To address this issue, a proposal was introduced in [1], known as hierarchical foreign agents or HFA. In this proposal, hierarchical foreign agents (HFAs) are introduced to smooth out the process when a MH transitions between subnets. This optimization is accomplished via hierarchical tracking of MHs by the FAs, and vi...
scalability;mobility;seamlessness;IP networks;local and metropolitan area networks;overlay infrastructure
599603
A Principal Components Approach to Combining Regression Estimates.
The goal of combining the predictions of multiple learned models is to form an improved estimator. A combining strategy must be able to robustly handle the inherent correlation, or multicollinearity, of the learned models while identifying the unique contributions of each. A progression of existing approaches and their...
Introduction Combining a set of learned models to improve classification and regression estimates has been an area of much research in machine learning and neural networks A learned model may be anything from a decision/regression tree to a neural network. The challenge of this problem is to decide which models to rely...
combining estimates;regression;principal components;multiple models
599620
Maximizing Theory Accuracy Through Selective Reinterpretation.
Existing methods for exploiting flawed domain theories depend on the use of a sufficiently large set of training examples for diagnosing and repairing flaws in the theory. In this paper, we offer a method of theory reinterpretation that makes only marginal use of training examples. The idea is as follows: Often a small...
Introduction A central concern of machine learning research is how to use prior knowledge effectively to provide a useful learning bias. An important type of prior knowledge that may thus be used is a flawed domain theory, obtained from some domain expert by knowledge engineering. One of the main methods for using such...
flawed domain theories;probabilistic theories;approximate reasoning;theory revision;logical theories;machine learning
599643
Relative Loss Bounds for On-Line Density Estimation with the Exponential Family of Distributions.
We consider on-line density estimation with a parameterized density from the exponential family. The on-line algorithm receives one example at a time and maintains a parameter that is essentially an average of the past examples. After receiving an example the algorithm incurs a loss, which is the negative log-likelihoo...
Introduction A main focus of statistical decision theory consists of the following: After receiving statistical information in the form of sampling data, the goal is to make decisions that minimize a loss or an expected loss with respect to an underlying distribution that is assumed to model the data. This distribution...
bregman divergences;relative loss bounds;worst-case loss bounds;linear regression;exponential family of distributions;on-line algorithms
599656
Linear Programming Boosting via Column Generation.
We examine linear program (LP) approaches to boosting and demonstrate their efficient solution using LPBoost, a column generation based simplex method. We formulate the problem as if all possible weak hypotheses had already been generated. The labels produced by the weak hypotheses become the new feature space of the p...
Introduction Recent papers [16] have shown that boosting, arcing, and related ensemble methods (hereafter summarized as boosting) can be viewed as margin maximization in function space. By changing the cost function, di#erent boosting methods such as AdaBoost can be viewed as gradient descent to minimize this cost func...
linear programming;boosting;ensemble learning;soft margin;sparseness
599662
On the Dual Formulation of Regularized Linear Systems with Convex Risks.
In this paper, we study a general formulation of linear prediction algorithms including a number of known methods as special cases. We describe a convex duality for this class of methods and propose numerical algorithms to solve the derived dual learning problem. We show that the dual formulation is closely related to ...
Introduction We consider the statistical learning problem: to find a parameter from random observations to minimize the expected loss (risk): given a loss function L(ff; x) and n observations independently drawn from a fixed but unknown distribution D, we want to find ff that minimizes the expected loss over x: Z any a...
logistic regression;support vector machine;linear model;regulation;augmented Lagrangian;convex duality
599663
Choosing Multiple Parameters for Support Vector Machines.
The problem of automatically tuning multiple parameters for pattern recognition Support Vector Machines (SVMs) is considered. This is done by minimizing some estimates of the generalization error of SVMs using a gradient descent algorithm over the set of parameters. Usual methods for choosing parameters, based on exhau...
Introduction In the problem of supervised learning, one takes a set of input-output pairs and attempts to construct a classier function f that maps input vectors x 2 X onto labels y 2 Y. We are interested here in pattern recognition or classication, that is the case where the set of labels is simply 1g. The goal is to ...
support vector machines;gradient descent;leave-one-out procedure;kernel selection;feature selection
599665
Efficient SVM Regression Training with SMO.
The sequential minimal optimization algorithm (SMO) has been shown to be an effective method for training support vector machines (SVMs) on classification tasks defined on sparse data sets. SMO differs from most SVM algorithms in that it does not require a quadratic programming solver. In this work, we generalize SMO s...
Introduction A support vector machine (SVM) is a type of model that is optimized so that prediction error and model complexity are simultaneously minimized [13]. Despite having many admirable qualities, research into the area of SVMs has been hindered by the fact that quadratic programming (QP) solvers provided the onl...
support vector machines;optimization;regression;caching;quadratic programming;sequential minimal optimization
599666
A Simple Decomposition Method for Support Vector Machines.
The decomposition method is currently one of the major methods for solving support vector machines. An important issue of this method is the selection of working sets. In this paper through the design of decomposition methods for bound-constrained SVM formulations we demonstrate that the working set selection is not a ...
Introduction The support vector machine (SVM) is a new and promising technique for classication. Surveys of SVM are, for example, Vapnik (1995, 1998) and Scholkopf et al. (1998). Given training vectors x i in two classes, and a vector y 2 R l such that 1g, the support vector technique requires the solution of the follo...
support vector machines;decomposition methods;classification
599667
Feasible Direction Decomposition Algorithms for Training Support Vector Machines.
The article presents a general view of a class of decomposition algorithms for training Support Vector Machines (SVM) which are motivated by the method of feasible directions. The first such algorithm for the pattern recognition SVM has been proposed in Joachims, T. (1999, Schlkopf et al. (Eds.) Advances in kernel meth...
Introduction Computational complexity of SVM training algorithms is attracting increasing interest, as applications of SVM extend to problems of larger and larger size. Requests have been recently made for algorithms capable of handling problems containing examples [14]. The basic training algorithm [16] involves a sol...
support vector machines;training;working set selection;decomposition algorithms;methods of feasible directions
599674
PAC Analogues of Perceptron and Winnow Via Boosting the Margin.
We describe a novel family of PAC model algorithms for learning linear threshold functions. The new algorithms work by boosting a simple weak learner and exhibit sample complexity bounds remarkably similar to those of known online algorithms such as Perceptron and Winnow, thus suggesting that these well-studied online ...
INTRODUCTION One of the most fundamental problems in computational learning theory is that of learning an unknown linear threshold function from labeled examples. Many different learning algorithms for this problem have been considered over the past several decades. In particular, in recent years many researchers have ...
linear threshold functions;probably approximately correct learning;boosting
599676
On the Learnability and Design of Output Codes for Multiclass Problems.
Output coding is a general framework for solving multiclass categorization problems. Previous research on output codes has focused on building multiclass machines given predefined output codes. In this paper we discuss for the first time the problem of designing output codes for multiclass problems. For the design prob...
Introduction Many applied machine learning problems require assigning labels to instances where the labels are drawn from a finite set of labels. This problem is often referred to as multiclass categorization or classification. Examples for machine learning applications that include a multiclass categorization componen...
SVM;output coding;multiclass categorization
599682
Metric-Based Methods for Adaptive Model Selection and Regularization.
We present a general approach to model selection and regularization that exploits unlabeled data to adaptively control hypothesis complexity in supervised learning tasks. The idea is to impose a metric structure on hypotheses by determining the discrepancy between their predictions across the distribution of unlabeled ...
Introduction In supervised learning, one takes a sequence of training pairs hx and attempts to infer a hypothesis function prediction error err(h(x); y) on future test examples. This basic paradigm covers many of the tasks studied in machine learning research, including: re- gression, where Y is typically IR and we mea...
unlabeled examples;model selection;regularization
599683
Model Selection and Error Estimation.
We study model selection strategies based on penalized empirical loss minimization. We point out a tight relationship between error estimation and data-based complexity penalization: any good error estimate may be converted into a data-based penalty function and the performance of the estimate is governed by the qualit...
Introduction We consider the following prediction problem. Based on a random observation one has to estimate Y 2 Y. A prediction rule is a measurable is a bounded loss function. The data consist of a sequence of independent, identically distributed samples with the same distribution as (X; Y ) and D n is independent of...
model selection;empirical penalties;concentration inequalities;penalization
599687
Sparse Regression Ensembles in Infinite and Finite Hypothesis Spaces.
We examine methods for constructing regression ensembles based on a linear program (LP). The ensemble regression function consists of linear combinations of base hypotheses generated by some boosting-type base learning algorithm. Unlike the classification case, for regression the set of possible hypotheses producible b...
Introduction The past years have seen strong interest in boosting and other ensemble learning algorithms due to their success in practical classication applications (e.g. Drucker et al., 1993; LeCun et al., 1995; Maclin & Opitz, 1997; Schwenk & Bengio, 1997; Bauer & Kohavi, 1999; Dietterich, 1999). The basic idea of bo...
boosting;semi-infinite programming;ensemble learning;regression;sparseness
599689
Logistic Regression, AdaBoost and Bregman Distances.
We give a unified account of boosting and logistic regression in which each learning problem is cast in terms of optimization of Bregman distances. The striking similarity of the two problems in this framework allows us to design and analyze algorithms for both simultaneously, and to easily adapt algorithms designed fo...
INTRODUCTION We give a unified account of boosting and logistic regression in which we show that both learning problems can be cast in terms of optimization of Bregman distances. In our frame- work, the two problems become extremely similar, the only real difference being in the choice of Bregman distance: un-normalize...
logistic regression;maximum-entropy methods;boosting;iterative scaling;convex optimization;information geometry;adaboost;bregman distances
599694
Reinforcement Learning for Call Admission Control and Routing under Quality of Service Constraints in Multimedia Networks.
In this paper, we solve the call admission control and routing problem in multimedia networks via reinforcement learning (RL). The problem requires that network revenue be maximized while simultaneously meeting quality of service constraints that forbid entry into certain states and use of certain actions. The problem ...
Introduction A number of researchers have recently explored the application of reinforcement learning (RL) to resource allocation and admission control problems in telecommu- nications, e.g., channel allocation in wireless systems, network routing, and admission control in telecommunication networks (Nie and Haykin, 19...
routing;reinforcement learning;call admission control;quality of service;multimedia networks
599699
Near-Optimal Reinforcement Learning in Polynomial Time.
We present new algorithms for reinforcement learning and prove that they have polynomial bounds on the resources required to achieve near-optimal return in general Markov decision processes. After observing that the number of actions required to approach the optimal return is lower bounded by the mixing time T of the o...
Introduction In reinforcement learning, an agent interacts with an unknown environment, and attempts to choose actions that maximize its cumulative payo (Sut- ton & Barto, 1998; Barto et al., 1990; Bertsekas & Tsitsiklis, 1996). The environment is typically modeled as a Markov decision process (MDP), and it is assumed ...
markov decision processes;reinforcement learning;exploration versus exploitation
599704
Variable Resolution Discretization in Optimal Control.
The problem of state abstraction is of central importance in optimal control, reinforcement learning and Markov decision processes. This paper studies the case of variable resolution state abstraction for continuous time and space, deterministic dynamic control problems in which near-optimal policies are required. We b...
Introduction This paper is about non-uniform discretization of state spaces when finding optimal controllers for continuous time and space Markov Processes. Uniform discretizations (generally based on finite element or finite difference techniques (Kushner & Dupuis, 1992) provide us with important convergence results (...
optimal control;reinforcement learning;variable resolution discretization;adaptive mesh refinement
599708
Classifiers that approximate functions.
A classifier system, XCSF, is introduced in which the prediction estimation mechanism is used to learn approximations to functions. The addition of weight vectors to the classifiers allows piecewise-linear approximation, where the classifier's prediction is calculated instead of being a fixed scalar. The weight vector ...
Introduction There is considerable recent research on the properties and performance of the learning classifier system XCS (Wilson 1995; Butz and Wilson 2001). Areas of interest include data mining (e.g. Bernad'o, Llor'a, and Garrell 2001), generalization over inputs (Butz and Pelikan 2001), self-adaptation of learning...
function approximation;continuous actions;generalized classifier;classifier systems
601777
Deciding the confluence of ordered term rewrite systems.
replace me
Introduction rewrite systems (TRS) have been applied to many problems in symbolic computa- tion, automated theorem proving, program synthesis and verification, and logic programming among others. Two fundamental properties of TRS are termination and confluence, which together ensure the existence and uniqueness of norm...
confluence;rewrite systems;ordered rewriting;path orderings
601779
Fixed-parameter complexity of semantics for logic programs.
A decision problem is called parameterized if its input is a pair of strings. One of these strings is referred to as a parameter. The following problem is an example of a parameterized decision problem with k serving as a parameter: given a propositional logic program P and a nonnegative integer k, decide whether P has...
Introduction In this paper we study the complexity of parameterized decision problems concerning models, supported models and stable models of logic programs. In our investigations, we use the framework of the fixed-parameter complexity introduced by Downey and Fellows [DF97]. This framework was previously used to stud...
stable models;normal logic programs;fixed-parameter complexity;supported models
601780
A complete characterization of complete intersection-type preorders.
We characterize those type preorders which yield complete intersection-type assignment systems for -calculi, with respect to the three canonical set-theoretical semantics for intersection-types: the inference semantics, the simple semantics, and the F-semantics. These semantics arise by taking as interpretation of type...
INTRODUCTION Intersection-types disciplines originated in [Coppo and Dezani-Ciancaglini 1980] to overcome the limitations of Curry's type assignment system and to provide a char- Author addresses: M. Dezani-Ciancaglini, Dipartimento di Informatica, Universita di Torino, Italy dezani@di.unito.it. F. Honsell and F.Alessi...
lambda models;lambda calculus;completeness;intersection types
602414
Architecture and algorithms for scalable mobile QoS.
Supporting Quality of Service (QoS) is an important objective for future mobile systems, and requires resource reservation and admission control to achieve. In this paper, we introduce an admission control scheme termed Virtual Bottleneck Cell, an approach designed to scale to many users and handoffs, while simultaneou...
Introduction Next generation wireless and mobile devices will support applications ranging from traditional cellular voice to web browsing and interactive multimedia applications. Concurrently, packet networks are evolving from the best effort model of the past to networks which support multiple service classes [25]. A...
admission control;mobile networks;adaptive clustering
603086
Efficient approximate planning in continuous space Markovian decision problems.
Monte-Carlo planning algorithms for planning in continuous state-space, discounted Markovian Decision Problems (MDPs) having a smooth transition law and a finite action space are considered. We prove various polynomial complexity results for the considered algorithms, improving upon several known bounds.
Introduction MDPs provide a clean and simple, yet fairly rich framework for studying various aspects of intelligence, such as, e.g., planning. A well-known practical limitation planning in MDPs is called the curse of dimensionality [1], referring to the exponential rise in the resources required to compute (even approx...
monte-carlo algorithms;markovian decision problems;value iteration;planning
603300
On-demand multicast routing protocol in multihop wireless mobile networks.
An ad hoc network is a dynamically reconfigurable wireless network with no fixed infrastructure or central administration. Each host is mobile and must act as a router. Routing and multicasting protocols in ad hoc networks are faced with the challenge of delivering data to destinations through multihop routes in the pr...
Introduction Multipoint communications [13] have emerged as one of the most researched areas in the field of network- ing. As the technology and popularity of Internet grow, applications, such as video conferencing, that require multicast support are becoming more widespread. Another interesting recent development has ...
routing;mobile computing;ad hoc networks;multicast
603301
Transmission range effects on AODV multicast communication.
As laptop computers begin to dominate the marketplace, wireless adapters with varying bandwidth and range capabilities are being developed by hardware vendors. To provide multihop communication between these computers, ad hoc mobile networking is receiving increasing research interest. While increasing a node's transmi...
Introduction Within the last few years, mobile computing has gained popularity as laptop computers have become smaller, lighter, and more powerful. It has become commonplace for professionals to carry their computers with them as they travel. With this increase in popularity has also come a greater demand for connectiv...
ad hoc networks;mobile networking;multicast;wireless networks
603342
High-level Language Support for User-defined Reductions.
The optimized handling of reductions on parallel supercomputers or clusters of workstations is critical to high performance because reductions are common in scientific codes and a potential source of bottlenecks. Yet in many high-level languages, a mechanism for writing efficient reductions remains surprisingly absent....
Introduction Reductions require careful compilation for two reasons. First, they abound in scientic codes. For example, they are used in algorithms for image processing and for computational geometry, in kernels for matrix multiplication and for sorting, and to test for convergence in iterative algorithms. Often a test...
high-level languages;parallel programming;scientific computing;user-defined reductions
603347
Design and Prototype of a Performance Tool Interface for OpenMP.
This paper proposes a performance tools interface for OpenMP, similar in spirit to the MPI profiling interface in its intent to define a clear and portable API that makes OpenMP execution events visible to runtime performance tools. We present our design using a source-level instrumentation approach based on OpenMP dir...
Introduction With the advent of any proposed language system for expressing parallel operation (whether as a true parallel language (e.g., ZPL [6]), parallel extensions to sequential language (e.g., UPC [4]), or parallel compiler directives (e.g., questions soon arise regarding how performance instrumentation and measu...
parallel programming;performance analysis;OpenMP
603408
Eliminating counterevidence with applications to accountable certificate management.
This paper presents a method to increase the accountability of certificate management by making it intractable for the certification authority (CA) to create contradictory statements about the validity of a certificate. The core of the method is a new primitive, undeniable attester, that allows someone to commit to som...
Introduction The concept of public-key cryptography was created in an effort to solve the cryptographic management problem [DH76]. While giving an answer to many difficult problems, public-key cryptography also raised several of its own. Not surprisingly, one of the main problematic areas to be solved before public-key...
attesters;long-term authenticity;accountable certificate management;search trees;public-key infrastructure;time-stamping;non-repudiation;authenticated search trees
603480
A formal model for an expressive fragment of XSLT.
The extension of the eXtensible Style sheet Language (XSL) by variables and passing of data values between template rules has generated a powerful XML query language: eXtensible Style sheet Language Transformations (XSLT). An informal introduction to XSTL is given, on the bases of which a formal model of a fragment of ...
Introduction XSL [6] is a current W3C [8] proposal for an XML extensible stylesheet lan- guage. Its original primary role was to allow users to write transformations of XML to HTML, thus describing the presentation of XML documents. Nowadays, many people use XSL as their basic tool for XML to XML transformations which ...
XSLT;expressiveness;logic;XML;databases;tree transducers;query languages
603514
Interactive video streaming with proxy servers.
We study caching strategies for proxies that cache VBR-encoded continuous media objects for highly interactive streaming applications. First, we develop a model for streaming VBR-encoded continuous media objects. This model forms the basis for a stream admission control criterion and our study of caching strategies. We...
Introduction The dramatic growth of the World Wide Web has spurred the deployment of proxy caches. These store frequently requested objects close to the clients in the hope of satisfying future client requests without contacting the origin server. Highly localized request patterns, which exhibit hot{spots, i.e., freque...
statistical QoS;streaming;VBR video;continuous media object;object replication;caching;replacement policy
603650
Relative undecidability in term rewriting.
For a hierarchy of properties of term rewriting systems related to termination we prove relative undecidability: For implications X Y in the hierarchy the property X is undecidable for term rewriting systems satisfying Y. For most implications we obtain this result for term rewriting systems consisting of a single rew...
Introduction In this paper we consider finite term rewriting systems (TRSs) over finite signa- tures. For these systems termination and confluence are desired properties that are sometimes very hard to prove. Classical results ([7, 9]) state that they are undecidable: no decision procedure exists getting an arbitrary f...
undecidability;term rewriting;termination
603668
Inheritance-based subtyping.
play a dual role in mainstream statically typed object-oriented languages, serving as both object generators and object types. In such languages, inheritance implies subtyping. In contrast, the theoretical language community has viewed this linkage as a mistake and has focused on subtyping relationships determined by t...
Introduction There is a great divide between the study of the foundations of object-oriented languages and the practice of mainstream object-oriented languages like JAVA[AG98] and C ++ [Str97]. One of the most striking examples of this divide is the r-ole that class inheritance plays in defining subtyping relations. In...
inheritance;type theory;programming languages;object-orientation;subtyping
603669
On inner classes.
Inner classes in object-oriented languages play a role similar to nested function definitions in functional languages, allowing an object to export other objects that have direct access to its own methods and instance variables. However, the similarity is deceptive: a close look at inner classes reveals significant sub...
Introduction It has often been observed that the gap between object-oriented and functional programming styles is not as large as it might first appear; in essence, an object is just a record of function closures. However, there are differences as well as similarities. On the one hand, objects and classes incorporate i...
language design;inner classes;language semantics
603795
Generating functions for generating trees.
Certain families of combinatorial objects admit recursive descriptions in terms of generating trees: each node of the tree corresponds to an object, and the branch leading to the node encodes the choices made in the construction of the object. Generating trees lead to a fast computation of enumeration sequences (someti...
Introduction Only the simplest combinatorial structures - like binary strings, permutations, or pure involutions (i.e., involutions with no fixed point) - admit product decompositions. In that case, the set\Omega n of objects of size n is isomorphic to a product Two properties result from such a strong decomposability ...
walks on a half-line;algebraic generating functions;d-finite generating functions;generating trees
603848
CDMA uplink power control as a noncooperative game.
We present a game-theoretic treatment of distributed power control in CDMA wireless systems. We make use of the conceptual framework of noncooperative game theory to obtain a distributed and market-based control mechanism. Thus, we address not only the power control problem, but also pricing and allocation of a single ...
Introduction In wireless communication systems, mobile users respond to the time-varying nature of the channel, described using short-term and long-term fading phenomena [1], by regulating their transmitter powers. Specically, in a code division multiple access (CDMA) system, where signals of other users can be modeled...
game theory;CDMA;power control;pricing;resource allocation
603891
Multivariate locally adaptive density estimation.
Multivariate versions of variable bandwidth kernel density estimators can lead to improvement over kernel density estimators using global bandwidth choices. These estimators are more flexible and better able to model complex (multimodal) densities. In this work, two variable bandwidth estimators are discussed: the ball...
Introduction The kernel density estimator has become a staple in the data analysis tool box largely because of the flexibility and generality of the method. Much research has been done on the theoretical properties of the kernel estimator and the superiority over such naive estimators as histograms is well-established....
binning;smoothing matrix;mean integrated squared error;cross-validation;variable band-width kernel
603893
Bayesian and likelihood methods for fitting multilevel models with complex level-1 variation.
In multilevel modelling it is common practice to assume constant variance at level 1 across individuals. In this paper we consider situations where the level-1 variance depends on predictor variables. We examine two cases using a dataset from educational research; in the first case the variance at level 1 of a test sco...
Introduction Over the past 15 years or so, tting multilevel models to data with a hierarchical or nested structure has become increasingly common for statisticians in many application areas (e.g., Goldstein 1986, 1995; Bryk and Raudenbush 1992; Draper 2000). The main purpose of tting such models is to partition the var...
maximum-likelihood methods;adaptive Metropolis-Hastings sampling;hierarchical modelling;educational data;IGLS;MCMC efficiency;Markov chain Monte Carlo MCMC;multilevel modelling;heteroscedasticity;RIGLS
604042
State-dependent M/G/1 type queueing analysis for congestion control in data networks.
We study a linear-increase multiplicative-decrease flow control mechanism. We consider congestion signals that arrive in batches according to a Poisson process. We focus on the case when the transmission rate cannot exceed a certain maximum value. The distribution of the transmission rate in steady state as well as its...
INTRODUCTION I N today's high speed telecommunication networks, a large part of the traffic is able to adapt its rate to the congestion conditions of the network. Congestion control is typically designed so as to allow the transmission rate to increase linearly in time in the absence of congestion signals, whereas when...
state-dependent queue;control protocol;linear increase and multiplicative decrease;congestion control in data networks;transmission
604062
Lessons learned in modeling schizophrenic and depressed responsive virtual humans for training.
This paper describes lessons learned in developing the linguistic, cognitive, emotional, and gestural models underlying virtual human behavior in a training application designed to train civilian police officers how to recognize gestures and verbal cues indicating different forms of mental illness and how to verbally i...
Figure 1: Avatalk Architecture Language Processor The Language Processor maps spoken input to underlying semantics and produces responsive output. It has six components [17]: Parsing. Our system uses a minimum distance translator parser that tries to match the spoken words to the closest grammatical sentence as define...
agents;behavior modeling;interaction skills training;managing encounters with the mentally ill;responsive virtual humans
604075
A reliable natural language interface to household appliances.
As household appliances grow in complexity and sophistication, they become harder and harder to use, particularly because of their tiny display screens and limited keyboards. This paper describes a strategy for building natural language interfaces to appliances that circumvents these problems. Our approach leverages de...
Table 1: The ?message_list? table is one of five relations comprising the database that EXACT uses to represent the state of the Panasonic KXTC1040W. message_number message Old Old Note that while we have fully implemented the EXACT NLIA, we have tested it on a simulation of the Panasonic device, rather than the actua...
planner;appliance;database;natural language interface
604133
Selective memoization.
We present a framework for applying memoization selectively. The framework provides programmer control over equality, space usage, and identification of precise dependences so that memoization can be applied according to the needs of an application. Two key properties of the framework are that it is efficient and yield...
We describe the framework in the context of a functional language and an implementation as an SML library. The language is based on a modal type system and allows the programmer to express programs that reveal their true data dependences when executed. The SML implementation cannot support this modal type system stati-...
programmer controlled;memoization;performance;selective
604139
Bitwidth aware global register allocation.
Multimedia and network processing applications make extensive use of subword data. Since registers are capable of holding a full data word, when a subword variable is assigned a register, only part of the register is used. New embedded processors have started supporting instruction sets that allow direct referencing of...
INTRODUCTION Programs that manipulate data at subword level, i.e. bit sections within a word, are common place in the embedded domain. Examples of such applications include media processing as well as network processing codes [12, 19]. A key characteristic of such applications is that at some point the data exists in p...
minimal bitwidth;packing interfering nodes;subword data;embedded applications
604147
A type theory for memory allocation and data layout.
Ordered type theory is an extension of linear type theory in which variables in the context may be neither dropped nor re-ordered. This restriction gives rise to a natural notion of adjacency. We show that a language based on ordered types can use this property to give an exact account of the layout of data in memory. ...
Introduction High-level programming languages such as ML and Java allow programmers to program in terms of abstractions such as pairs, records, and objects, which have well-defined semantics but whose realizations in terms of the underlying concrete machine are left unspecified and unobservable. Sometimes, it is necess...
memory management;type theory;data representation;ordered logic
604149
Toward a foundational typed assembly language.
We present the design of a typed assembly language called TALT that supports heterogeneous tuples, disjoint sums, and a general account of addressing modes. TALT also implements the von Neumann model in which programs are stored in memory, and supports relative addressing. Type safety for execution and for garbage coll...
Introduction The proliferation of low-cost computing hardware and the ubiquity of the Internet has created a situation where a huge amount of computing power is both idle and-in principle-accessible to developers. The goal of exploiting these idle computational resources has existed for years, and, beginning with SETI@...
typed assembly language;proof-carrying code
604151
A type system for higher-order modules.
We present a type theory for higher-order modules that accounts for many central issues in module system design, including translucency, applicativity, generativity, and modules as first-class values. Our type system harmonizes design elements from previous work, resulting in a simple, economical account of modular pro...
Introduction The design of languages for modular programming is surprisingly delicate and complex. There is a fundamental tension between # The ConCert Project is supported by the National Science Foundation under grant number 0121633: "ITR/SY+SI: Language Technology for Trustless Software Dissemination". Permission to...
modularity;singleton types;computational effects;functors;abstract data types;type theory;generativity
604154
Interprocedural compatibility analysis for static object preallocation.
We present an interprocedural and compositional algorithm for finding pairs of compatible allocation sites, which have the property that no object allocated at one site is live at the same time as any object allocated at the other site. If an allocation site is compatible with itself, it is said to be unitary: at most ...
INTRODUCTION Modern object-oriented languages such as Java present a clean and simple memory model: conceptually, all objects are allocated in a garbage-collected heap. While this abstraction simplies many aspects of the program devel- opment, it can complicate the calculation of an accurate upper bound on the amount o...
interprocedural analysis;memory preallocation;static analysis
604155
A real-time garbage collector with low overhead and consistent utilization.
Now that the use of garbage collection in languages like Java is becoming widely accepted due to the safety and software engineering benefits it provides, there is significant interest in applying garbage collection to hard real-time systems. Past approaches have generally suffered from one of two major flaws: either t...
INTRODUCTION Garbage collected languages like Java are making significant inroads into domains with hard real-time concerns, such as automotive command-and-control systems. However, the engineering and product life-cycle advantages consequent from the simplicity of Permission to make digital or hard copies of all or pa...
real-time scheduling;read barrier;defragmentation;utilization
604156
Ownership types for object encapsulation.
Ownership types provide a statically enforceable way of specifying object encapsulation and enable local reasoning about program correctness in object-oriented languages. However, a type system that enforces strict object encapsulation is too constraining: it does not allow efficient implementation of important constru...
Introduction The ability to reason locally about program correctness is crucial when dealing with large programs. Local reasoning allows correctness to be dealt with one module at a time. Each module has a specication that describes its expected behavior. The goal is to prove that each module satises its The research w...
software upgrades;ownership types;object encapsulation
604166
On the computational complexity of assumption-based argumentation for default reasoning.
Bondarenko et al. have recently proposed an abstract framework for default reasoning. Besides capturing most existing formalisms and proving that their standard semantics all coincide, the framework extends these formalisms by generalising the semantics of admissible and preferred arguments, originally proposed for log...
Introduction Bondarenko et al. [1] show that many logics for default reasoning, i.e., theorist [25], (many cases of) circumscription [20], Default Logic (DL) [26], Nonmonotonic Modal Logic [21], Autoepistemic Logic (AEL) [22], and Logic Programming (LP) can be understood as special cases of a single abstract framework....
default reasoning;non-monotonic reasoning;abduction;argumentation;assumption-based reasoning;computational complexity