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Computer Sciences

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1999

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Articles 1 - 30 of 284

Full-Text Articles in Physical Sciences and Mathematics

Experiments To Assess The Cost-Benefits Of Test-Suite Reduction, Gregg Rothermel, Mary Jean Harrold, Jeffery Von Ronne, Christie Hang, Jeffery Ostrin Dec 1999

Experiments To Assess The Cost-Benefits Of Test-Suite Reduction, Gregg Rothermel, Mary Jean Harrold, Jeffery Von Ronne, Christie Hang, Jeffery Ostrin

CSE Technical Reports

Test-suite reduction techniques attempt to reduce the cost of saving and reusing test cases during software maintenance by eliminating redundant test cases from test suites. A potential drawback of these techniques is that in reducing a test suite they might reduce the ability of that test suite to reveal faults in the software. Previous studies suggested that test-suite reduction techniques can reduce test suite size without significantly reducing the fault-detection capabilities of test suites. To further investigate this issue we performed experiments in which we examined the costs and benefits of reducing test suites of various sizes for several programs …

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Characterizations Of Classes Of Programs By Three-Valued Operators, Anthony K. Seda, Pascal Hitzler Dec 1999

Characterizations Of Classes Of Programs By Three-Valued Operators, Anthony K. Seda, Pascal Hitzler

Computer Science and Engineering Faculty Publications

Several important classes of normal logic programs, including the classes of acyclic, acceptable, and locally hierarchical programs, have the property that every program in the class has a unique two-valued supported model. In this paper, we call such classes unique supported model classes. We analyse and characterize these classes by means of operators on three-valued logics. Our studies will motivate the definition of a larger unique supported model class which we call the class of Phi-accessible programs. Finally, we show that the class of Phi -accessible programs is computationally adequate in that every partial recursive function can be implemented by …

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Towards The Evaluation Of Netcentric Scientific Applications, Shanhani Markus, Elias N. Houstis Dec 1999

Towards The Evaluation Of Netcentric Scientific Applications, Shanhani Markus, Elias N. Houstis

Department of Computer Science Technical Reports

No abstract provided.

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Off-Line Compression By Greedy Textual Substitution, Alberto Apostolico, Stefano Lonardi Dec 1999

Off-Line Compression By Greedy Textual Substitution, Alberto Apostolico, Stefano Lonardi

Department of Computer Science Technical Reports

No abstract provided.

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String Pattern Matching For A Deluge Survival Kit, Alberto Apostolico, Maxime Crochemore Dec 1999

String Pattern Matching For A Deluge Survival Kit, Alberto Apostolico, Maxime Crochemore

Department of Computer Science Technical Reports

No abstract provided.

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Experimental Evaluation Of Design Tradeoff In Specialized Virtual Machine For Multimedia Traffic In Active Networks, Sheng-Yih Wang, Bharat Bhargava Dec 1999

Experimental Evaluation Of Design Tradeoff In Specialized Virtual Machine For Multimedia Traffic In Active Networks, Sheng-Yih Wang, Bharat Bhargava

Department of Computer Science Technical Reports

No abstract provided.

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An Adaptable Network Architecture For Multimedia Traffic Management And Control, Sheng-Yih Wang, Bharat Bhargava Dec 1999

An Adaptable Network Architecture For Multimedia Traffic Management And Control, Sheng-Yih Wang, Bharat Bhargava

Department of Computer Science Technical Reports

No abstract provided.

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A Hierarchy Of Maps Between Compacta, Paul Bankston Dec 1999

A Hierarchy Of Maps Between Compacta, Paul Bankston

Mathematics, Statistics and Computer Science Faculty Research and Publications

Let CH be the class of compacta (i.e., compact Hausdorff spaces), with BS the subclass of Boolean spaces. For each ordinal α and pair $\langle K,L\rangle$ of subclasses of CH, we define Lev≥α K,L), the class of maps of level at least α from spaces in K to spaces in L, in such a way that, for finite α, Lev≥α (BS,BS) consists of the Stone duals of Boolean lattice embeddings that preserve all prenex first-order formulas of quantifier rank α. Maps of level ≥ 0 are just the continuous surjections, and the maps of level ≥ 1 are …

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A Model For Active Techniques For Compressed Video Transmission, Sheng-Yih Wang, Bharat Bhargava Dec 1999

A Model For Active Techniques For Compressed Video Transmission, Sheng-Yih Wang, Bharat Bhargava

Department of Computer Science Technical Reports

No abstract provided.

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Disclosure Detection In Multivariate Categorical Databases: Auditing Confidentiality Protection Through Two New Matrix Operators, Sumit Dutta Chowdhury, George T. Duncan, Ramayya Krishnan, Stephen F. Roehrig, Sumitra Mukherjee Dec 1999

Disclosure Detection In Multivariate Categorical Databases: Auditing Confidentiality Protection Through Two New Matrix Operators, Sumit Dutta Chowdhury, George T. Duncan, Ramayya Krishnan, Stephen F. Roehrig, Sumitra Mukherjee

CCE Faculty Articles

As databases grow more prevalent and comprehensive, database administrators seek to limit disclosure of confidential information while still providing access to data. Practical databases accommodate users with heterogeneous needs for access. Each class of data user is accorded access to only certain views. Other views are considered confidential, and hence to be protected. Using illustrations from health care and education, this article addresses inferential disclosure of confidential views in multidimensional categorical databases. It demonstrates that any structural, so data-value-independent method for detecting disclosure can fail. Consistent with previous work for two-way tables, it presents a data-value-dependent method to obtain tight …

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On-Line Bayesian Tree-Structured Transformation Of Hidden Markov Models For Speaker Adaptation, Shaojun Wang, Yunxin Zhao Dec 1999

On-Line Bayesian Tree-Structured Transformation Of Hidden Markov Models For Speaker Adaptation, Shaojun Wang, Yunxin Zhao

Kno.e.sis Publications

This paper presents a new recursive Bayesian learning approach for transformation parameter estimation in speaker adaptation. Our goal is to incrementally transform (or adapt) the entire set of HMM parameters for a new speaker or new acoustic enviroment from a small amount of adaptation data. By establishing a clustering tree of HMM Gaussian mixture components, the finest affine transformation parameters for individual HMM Gaussian mixture components can be dynamically searched. The on-line Bayesian learning technique proposed in our recent work is used for recursive maximum a posteriori estimation of affine transformation parameters. Speaker adaptation experiments using a 26-letter English alphabet …

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Optimal Power Allocation In Cdma Forward Link Using Dependency Between Pilot And Traffic Channels, Seung Jong Park, Dongwoo Kim, Chang Yeon Kim Dec 1999

Optimal Power Allocation In Cdma Forward Link Using Dependency Between Pilot And Traffic Channels, Seung Jong Park, Dongwoo Kim, Chang Yeon Kim

Computer Science Faculty Research & Creative Works

This paper shows a new method for minimizing the transmit power on CDMA forward link channels. Different from previous works, the proposed method uses the dependency that exists between the respective signal qualities of the pilot channel and traffic channels. Since present CDMA forward link exploits coherent demodulation with continuously transmitting pilot signals, the stronger the pilot channel is, the less traffic power may be required while the same transmission quality is maintained. With laboratory tests, the dependency is graphed. And then an optimal pilot signal quality is found, which minimizes the total transmit power. Considering various mobile environments, -10 …

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A Comparison Of Training Algorithms For Dhp Adaptive Critic Neuro-Control, George G. Lendaris, Thaddeus T. Shannon, Andres Rustan Dec 1999

A Comparison Of Training Algorithms For Dhp Adaptive Critic Neuro-Control, George G. Lendaris, Thaddeus T. Shannon, Andres Rustan

Systems Science Faculty Publications and Presentations

A variety of alternate training strategies for implementing the Dual Heuristic Programming (DHP) method of approximate dynamic programming in the neuro-control context are explored. The DHP method of controller training has been successfully demonstrated by a number of authors on a variety of control problems in recent years, but no unified view of the implementation details of the method has yet emerged. A number of options are here described for sequencing the training of the Controller and Critic networks in DHP implementations. Results are given about their relative efficiency and the quality of the resulting controllers for two benchmark control …

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A Simplified Model Of Wound Healing - Ii: The Critical Size Defect In Two Dimensions, J. S. Arnold, John A. Adam Dec 1999

A Simplified Model Of Wound Healing - Ii: The Critical Size Defect In Two Dimensions, J. S. Arnold, John A. Adam

Mathematics & Statistics Faculty Publications

Recently, a one-dimensional model was developed which gives a reasonable explanation for the existence of a Critical Size Defect (CSD) in certain animals [1]. In this paper, we examine the more realistic two-dimensional model of a circular wound of uniform depth to see what modifications are to be found, as compared with the one-dimensional model, in studying the CSD phenomenon. It transpires that the range of CSD sizes for a reasonable estimate of parameter values is 1 mm-1 cm. More realistic estimates await the appropriate experimental data.

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Computational Geometry Column 36, Joseph O'Rourke Dec 1999

Computational Geometry Column 36, Joseph O'Rourke

Computer Science: Faculty Publications

Two results in "computational origami" are illustrated.

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The Window Distribution Of Multiple Tcps With Random Loss Queues, Archan Misra, Teunis Ott, John Baras Dec 1999

The Window Distribution Of Multiple Tcps With Random Loss Queues, Archan Misra, Teunis Ott, John Baras

Research Collection School Of Computing and Information Systems

Two approximate techniques for analyzing the window size distribution of TCP flows sharing a RED-like bottleneck queue are presented. Both methods presented first use a fixed point algorithm to obtain the mean window sizes of the flows, and the mean queue length in the bottleneck buffer. The simpler of the two methods then uses the ‘square root formula’ for TCP; the other method is more complicated. More often than not, the simpler method is slightly more accurate; this is probably due to the fact that window sizes of the different flows are negatively correlated.

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Work In Progress: Automating Proportion/Period Scheduling, David Steere, Jonathan Walpole, Calton Pu Dec 1999

Work In Progress: Automating Proportion/Period Scheduling, David Steere, Jonathan Walpole, Calton Pu

Computer Science Faculty Publications and Presentations

The recent effort to define middleware capable of supporting real-time applications creates the opportunity to raise the level of abstraction presented to the programmer. We propose that proportion/period is a better abstraction for specifying resource needs and allocation than priorities. We are currently investigating techniques to address some issues that are restricting use of proportion/period scheduling to research real-time prototypes. In particular, we are investigating techniques to automate the task of selecting proportion and period, and that allow proportion/period to incorporate job importance under overload conditions.

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Pushpush Is Np-Hard In 3d, Joseph O'Rourke, The Smith Problem Solving Group Nov 1999

Pushpush Is Np-Hard In 3d, Joseph O'Rourke, The Smith Problem Solving Group

Computer Science: Faculty Publications

We prove that a particular pushing-blocks puzzle is intractable in 3D. The puzzle, inspired by the game PushPush, consists of unit square blocks on an integer lattice. An agent may push blocks (but never pull them) in attempting to move between given start and goal positions. In the PushPush version, the agent can only push one block at a time, and moreover, each block, when pushed, slides the maximal extent of its free range. We prove this version is NP-hard in 3D by reduction from SAT. The corresponding problem in 2D remains open.

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Immaccs: A Military Decision-Support System, Jens G. Pohl, Anthony A. Wood, Kym Jason Pohl, Arthur J. Chapman Nov 1999

Immaccs: A Military Decision-Support System, Jens G. Pohl, Anthony A. Wood, Kym Jason Pohl, Arthur J. Chapman

Collaborative Agent Design (CAD) Research Center

The Integrated Marine Multi-Agent Command and Control System (IMMACCS) is a multi-agent, distributed system, designed to provide a ‘common tactical picture’ with integrated and meaningful decision-support facilities to authorized operators at any access node. IMMACCS has been implemented as a three-tier architecture that distinguishes between information, logic and presentation. It utilizes an object-serving communication facility with subscription and multi-casting capabilities that is based on the Common Object Request Broker Architecture (CORBA). With an emphasis on application, IMMACCS was designed and implemented in concert with its military users as an integral component of experiments conceived by the Marine Corps Warfighting Laboratory …

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Evaluating Maximum Likelihood Estimation Methods To Determine The Hurst Coefficient, Christina Marie Kendziorski, J. B. Bassingthwaighte, Peter J. Tonellato Nov 1999

Evaluating Maximum Likelihood Estimation Methods To Determine The Hurst Coefficient, Christina Marie Kendziorski, J. B. Bassingthwaighte, Peter J. Tonellato

Mathematics, Statistics and Computer Science Faculty Research and Publications

A maximum likelihood estimation method implemented in S-PLUS (S-MLE) to estimate the Hurst coefficient (H) is evaluated. The Hurst coefficient, with 0.5<HS-MLE was developed to estimate H for fractionally differenced (fd) processes. However, in practice it is difficult to distinguish between fd processes and fractional Gaussian noise (fGn) processes. Thus, the method is evaluated for estimating H for both fd and fGn processes. S-MLE gave biased results of H for fGn processes of any length and for fd processes of lengths less than 210. A modified method is proposed to correct for …

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Mental Models For Introductory Csc Concepts, Jennifer J. Wheeler, Erika Rogers Nov 1999

Mental Models For Introductory Csc Concepts, Jennifer J. Wheeler, Erika Rogers

Computer Science and Software Engineering

If is hypothesized that the development of mental models for a concept can lead to improved learning. The purpose of this paper is to identify, quantify, and analyze the mental models of students beginning to program in the UNIX environment. By focusing on 4 basic concept, this study abstracts current mental models from students and hypothesizes ways of improving these models. Ultimately, the results of the study will be incorporated into the design and implementation of a multimedia tutor. This tutor will attempt to teach people how to develop mental models in order to improve their learning.

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Teaching Object Technology In Industry Short Courses, David S. Janzen Nov 1999

Teaching Object Technology In Industry Short Courses, David S. Janzen

Computer Science and Software Engineering

No abstract provided.

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An Access-Control Calculus For Spanning Administrative Domains, Jon Howell, David Kotz Nov 1999

An Access-Control Calculus For Spanning Administrative Domains, Jon Howell, David Kotz

Computer Science Technical Reports

In our quest to give users uniform access to resources unimpeded by administrative boundaries, we discovered that we needed transitive sharing among users, with the possibility of restricted access along each sharing link. To achieve that goal, we extend Lampson et al.'s calculus for access control to support restricted delegations. We discuss the advantages of our extension, including the simplification of constructs like ACLs and statement expiration. We also apply our extension to model the Simple Public Key Infrastructure and make suggestions about its future development. Our extended calculus exposes some surprising consequences in such systems that use restricted delegation.

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Performance Evaluation Of Cpu Isolation Miechanisms In A Multithreaded Os Kernel, David K.Y. Yau Nov 1999

Performance Evaluation Of Cpu Isolation Miechanisms In A Multithreaded Os Kernel, David K.Y. Yau

Department of Computer Science Technical Reports

No abstract provided.

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Kinematic Analysis Of Spatial Fixed-Axes Pairs Using Configuration Spaces, Ku-Jin Kim, Elisha Sacks, Leo Joskowicz Nov 1999

Kinematic Analysis Of Spatial Fixed-Axes Pairs Using Configuration Spaces, Ku-Jin Kim, Elisha Sacks, Leo Joskowicz

Department of Computer Science Technical Reports

No abstract provided.

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On Learning Probabilistic Automata, Alberto Apostolico Nov 1999

On Learning Probabilistic Automata, Alberto Apostolico

Department of Computer Science Technical Reports

No abstract provided.

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Performance Evaluation Of Multiple Time Scale Tcp Under Self-Similar Traffic Conditions, Tsunyi Tuan, Kihong Park Nov 1999

Performance Evaluation Of Multiple Time Scale Tcp Under Self-Similar Traffic Conditions, Tsunyi Tuan, Kihong Park

Department of Computer Science Technical Reports

No abstract provided.

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Optimal Discovery Of Subword Associations In Strings, Alberto Apostolico, Giorgio Satta Nov 1999

Optimal Discovery Of Subword Associations In Strings, Alberto Apostolico, Giorgio Satta

Department of Computer Science Technical Reports

No abstract provided.

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Leveraging Legacy Scientific Software With Mobile Agent Technology, Shanhani Markus, Elias N. Houstis Nov 1999

Leveraging Legacy Scientific Software With Mobile Agent Technology, Shanhani Markus, Elias N. Houstis

Department of Computer Science Technical Reports

No abstract provided.

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Compression Of Biological Sequences By Greedy Off-Line Textual Subsitution, Alberto Apostolico, Stefano Lonardi Nov 1999

Compression Of Biological Sequences By Greedy Off-Line Textual Subsitution, Alberto Apostolico, Stefano Lonardi

Department of Computer Science Technical Reports

No abstract provided.

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