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Computer Science Faculty Research & Creative Works

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Full-Text Articles in Computer Sciences

Termination Via Conditional Reductions, Timothy B. Baird, Ralph W. Wilkerson Apr 1991

Termination Via Conditional Reductions, Timothy B. Baird, Ralph W. Wilkerson

Computer Science Faculty Research & Creative Works

We Generalize the Notion of Rewriting Modulo an Equational Theory to Include a Special Form of Conditional Reduction. We Are Able to Show that This Conditional Rewriting Relation Restores the Finite Termination Property Which is Often Lost When Rewriting in the Presence of Infinite Congruence Classes. in Particular, We Are Able to Handle the Class of Collapse Equational Theories Which Contain Associative, Commutative, and Identity Laws for One or More Operators.


A Model-Based Approach For Organizing Quantitative Computations, J. Sticklen, A. Kamel, William E. Bond Jan 1991

A Model-Based Approach For Organizing Quantitative Computations, J. Sticklen, A. Kamel, William E. Bond

Computer Science Faculty Research & Creative Works

Model based reasoning (MBR) is currently receiving wide spread attention because it offers a way to circumvent the brittleness of reasoning systems built solely on associational knowledge. To date, most MBR approaches have focused on the use and manipulation of qualitative models. The authors report their experience in applying techniques of functional reasoning to the general problem of organizing quantitative calculations. As a testbed, they have solved a problem initially posed at the Model-Based Diagnosis workshop (Paris, July, 1989): representing an automotive cruise control system. The results show that the principles of the functional reasoning approach can provide leverage in …


Simulating Adaptive Load Sharing Policies On An Ipsc/2 Multicomputer, Yuh Jong Hu, Billy E. Gillett Jan 1991

Simulating Adaptive Load Sharing Policies On An Ipsc/2 Multicomputer, Yuh Jong Hu, Billy E. Gillett

Computer Science Faculty Research & Creative Works

Unlike most other adaptive load sharing (LS) policy studies, each node in the distributed system is modeled as a central server model represented by a closed queueing network (QN). The primary objective of this study is to use a simulation model to find the improvement for an adaptive LS policy in a distributed system. In homogeneous distributed systems, the simulation results in this study show that the performance improvements between no LS, LS with task placement, and LS with task migration are very small. These results are quite different from other studies, which show a significant improvement of mean response …


Fault-Tolerant Parallel Matrix Multiplication With One Iteration Fault Detection Latency, Chul Eui Hong, Bruce M. Mcmillin Jan 1991

Fault-Tolerant Parallel Matrix Multiplication With One Iteration Fault Detection Latency, Chul Eui Hong, Bruce M. Mcmillin

Computer Science Faculty Research & Creative Works

The checksum technique is a low-cost method to detect errors in matrix operations performed by processor arrays. The fault detection of this method is done only at problem termination, so this method is not an effective fault tolerance technique for large scale matrix multiplication. This paper presents a new algorithm, the ID algorithm, which minimizes the fault-detection latency, In the ID algorithm, a fault is detected as soon as the fault occurs instead of at problem termination. For n2 processors, the fault-latency time of the ID algorithm is l/n of that of checksum algorithm with a run-time penalty of O(nlog2n) …


Pattern Recognition For Nondestructive Evaluation, S. Morris, P. O'Rorke, William E. Bond, M. M. Amirfathi, Daniel C. St. Clair Jan 1991

Pattern Recognition For Nondestructive Evaluation, S. Morris, P. O'Rorke, William E. Bond, M. M. Amirfathi, Daniel C. St. Clair

Computer Science Faculty Research & Creative Works

The issues involved in automating nondestructive evaluation (NDE) techniques are outlined. Attention is given to research focused on the application of machine learning techniques to the construction and maintenance of knowledge-based systems which are capable of evaluating the readings from nondestructive tests that have been performed on aircraft components. Preliminary results obtained from this research are described. In particular, the authors discuss the application of a symbolic machine learning algorithm, ID3, to the NDE problem. ID3 has been used by Douglas Aircraft to classify defects in sets of standard NDE reference blocks. Based on the preliminary results, a need for …


A Visualization Model For Massively Parallel Algorithms, Rashi Khanna, Bruce M. Mcmillin Jan 1991

A Visualization Model For Massively Parallel Algorithms, Rashi Khanna, Bruce M. Mcmillin

Computer Science Faculty Research & Creative Works

A visualization model has been developed to analyze the performance of a massively parallel algorithm. Most visualization tools that have been developed so far for performance analysis are based generally on individual processor information and communication patterns. These tools, however, are inadequate for massively parallel computations. It is difficult to comprehend the visual information for many processors. The model, SMILI (Scientific visualization in Multicomputing for Interpretation of Large amounts of Information), addresses this problem by using abstract representations to attain a composite picture which gives better insight to the behavior of the algorithm. Chernoff s Faces have been selected to …


Functional Reasoning And Functional Modelling, J. Sticklen, William E. Bond Jan 1991

Functional Reasoning And Functional Modelling, J. Sticklen, William E. Bond

Computer Science Faculty Research & Creative Works

A car that will not start on a cold winter day and one that will not start on a hot summer day usually indicate two very different situations. When pressed to explain the difference, we would give a winter account- "Oil is more viscous in cold conditions, and that causes . . .'' -and a summer story- "Vapor lock is a possibility in hot weather and is usually caused by . . .'' How do we build such explanations? One possibility is that understanding how the car works as a device gives us a basis for generating the explanations. But …


Parallel Implementation Of A Recursive Least Squares Neural Network Training Method On The Intel Ipsc/2, James Edward Steck, Bruce M. Mcmillin, K. Krishnamurthy, M. Reza Ashouri, Gary G. Leininger Jun 1990

Parallel Implementation Of A Recursive Least Squares Neural Network Training Method On The Intel Ipsc/2, James Edward Steck, Bruce M. Mcmillin, K. Krishnamurthy, M. Reza Ashouri, Gary G. Leininger

Computer Science Faculty Research & Creative Works

An algorithm based on the Marquardt-Levenberg least-square optimization method has been shown by S. Kollias and D. Anastassiou (IEEE Trans. on Circuits Syst. vol.36, no.8, p.1092-101, Aug. 1989) to be a much more efficient training method than gradient descent, when applied to some small feedforward neural networks. Yet, for many applications, the increase in computational complexity of the method outweighs any gain in learning rate obtained over current training methods. However, the least-squares method can be more efficiently implemented on parallel architectures than standard methods. This is demonstrated by comparing computation times and learning rates for the least-squares method implemented …


Highland: A Graph-Based Parallel Processing Environment For Heterogeneous Local Area Networks, Ralph W. Wilkerson, Douglas E. Meyer Jan 1990

Highland: A Graph-Based Parallel Processing Environment For Heterogeneous Local Area Networks, Ralph W. Wilkerson, Douglas E. Meyer

Computer Science Faculty Research & Creative Works

No abstract provided.


Computational Intelligence In Cad/Cam Applications, Chaman Sabharwal, Thomas G. Melson, Martin D. Fraser Jan 1990

Computational Intelligence In Cad/Cam Applications, Chaman Sabharwal, Thomas G. Melson, Martin D. Fraser

Computer Science Faculty Research & Creative Works

This paper presents a fundamental, direct, and powerful approach to the surface/surface intersection problem in CAD/CAM applications. The algorithm is designed and implemented in three steps: a) Preprocessing- locate the potentially intersecting sections of the surfaces and decompose the surfaces into surface elements within specified flatness tolerance; b) Intersection- decompose the possibly intersecting pairs of surface elements into continuous surface triangulations to find the approximate intersections between the pairs of surface elements; c) Postprocessing-assemble the intersection primitives into curves of intersection, refine the accuracy of computed intersection points, and compact the intersection curves. This surface/surface intersection algorithm is applicable to …


Role Of Term Symmetry In E-Completion Procedures, Ralph W. Wilkerson, Blayne E. Mayfield Jan 1990

Role Of Term Symmetry In E-Completion Procedures, Ralph W. Wilkerson, Blayne E. Mayfield

Computer Science Faculty Research & Creative Works

No abstract provided.


Dawgs - A Distributed Compute Server Utilizing Idle Workstations, Henry Clark, Bruce M. Mcmillin Jan 1990

Dawgs - A Distributed Compute Server Utilizing Idle Workstations, Henry Clark, Bruce M. Mcmillin

Computer Science Faculty Research & Creative Works

A collection of powerful workstations interconnected by a local area network can be utilized as compute servers when left idle by their owners. DAWGS allows users to submit jobs for execution on an idle workstation somewhere on a local area network. DAWGS uses a distributed scheduler and a bidding scheme to determine on which machine to run a process. DAWGS can properly redirect all the I/O of a remotely executing process and can checkpoint and then subsequently restart the process, even if the restart is on a different machine than the checkpoint. Our method is different from other work in …


Distributed Evaluation Of An Iterative Function For All Object Pairs On A Simd Hypercube, Fikret Erçal Jan 1990

Distributed Evaluation Of An Iterative Function For All Object Pairs On A Simd Hypercube, Fikret Erçal

Computer Science Faculty Research & Creative Works

An efficient distributed algorithm for evaluating an iterative function on all pairwise combinations of C objects on an SIMD hypercube is presented. The algorithm achieves uniform load distribution and minimal, completely local interprocessor communication.


Experimentation With Large-Grained Parallelism Using Local Area Networks, Ralph W. Wilkerson, Douglas E. Meyer Jan 1990

Experimentation With Large-Grained Parallelism Using Local Area Networks, Ralph W. Wilkerson, Douglas E. Meyer

Computer Science Faculty Research & Creative Works

HIGHLAND, a distributed-memory parallel processing environment for heterogeneous local area networks, has been developed. Designed as both a teaching and a research tool, its purpose is to provide an effective mechanism by which a number of networked UNIX workstations, dissimilar in both vendor and performance, can be directly manipulated as a single, unified, multiprocessing system. Utilizing the MIT X-windows environment, HIGHLAND supports a highly interactive graphical interface through which a programmer can create, modify, and control complex systems of communicating processes


Experimental Comparison Of Bidding And Drafting Load Sharing Protocols, Andrew Ross, Bruce M. Mcmillin Jan 1990

Experimental Comparison Of Bidding And Drafting Load Sharing Protocols, Andrew Ross, Bruce M. Mcmillin

Computer Science Faculty Research & Creative Works

In recent years, a dramatic rise in the number of personal workstations interconnected via local area networks has occurred in the workplace. These can be organized as distributed computing systems. The combined computing power of these systems are often greater than mainframes of a decade ago, and usually less expensive. There is a growing interest in harnessing this often-underutilized power. Researchers are focusing their attention on remote execution of processes as one solution. An additional topic of research is to balance a workload among a series of computers. Remote execution is made possible because the distributed operating system provides migration …


An Expert System To Convert Knowledge-Based Geological Engineering Systems Into Fortran, Ralph W. Wilkerson, Jill J. Cress Jan 1990

An Expert System To Convert Knowledge-Based Geological Engineering Systems Into Fortran, Ralph W. Wilkerson, Jill J. Cress

Computer Science Faculty Research & Creative Works

A knowledge-based geographic information system (KBGIS) for geological engineering map (GEM) production was developed in GoldWorks, an expert system development shell. Using this shell, the geological engineer is able to develop a rule base for a particular application that results in a valid GEM. However, this implementation failed as a practical production system due to the excessive execution time required to produce a GEM. To solve this problem, a conversion expert system was developed which accepted, as input, a KBGIS and produced, as output, the equivalent Fortran code. Two major objectives are accomplished as a result of this system: GEN …


Safe Computing, Bruce M. Mcmillin, T. L. Casavant Jan 1989

Safe Computing, Bruce M. Mcmillin, T. L. Casavant

Computer Science Faculty Research & Creative Works

So-called worms, viruses, and Trojan horses that attack computer systems are defined. The vehicle that allows these attacks to occur, namely, the open computer internetwork, is examined. The problem of providing protection against attack in an internetwork environment is discussed. The need for professional responsibility on the part of the scientific and engineering community in enforcing strong ethical practices and neither tolerating nor condoning such practices is stressed.


Expectations For Associative-Commutative Unification Speedups In A Multicomputer Environment, Ralph W. Wilkerson, Bruce M. Mcmillin Jan 1989

Expectations For Associative-Commutative Unification Speedups In A Multicomputer Environment, Ralph W. Wilkerson, Bruce M. Mcmillin

Computer Science Faculty Research & Creative Works

An essential element of automated deduction systems is unification algorithms which identify general substitutions and when applied to two expressions, make them identical. However, functions which are associative and commutative, such as the usual addition and multiplication functions, often arise in term rewriting systems, program verification, the theory of abstract data types and logic programming. The introduction to the associative and commutative equality axioms together with standard unification brings with it problems of termination and unreasonably large search spaces. One way around these problems is to remove the troublesome axioms from the system and to employ a unification algorithm which …


Fault Diagnosis Using First Order Logic Tools, Ralph W. Wilkerson, Barbara A. Smith Jan 1989

Fault Diagnosis Using First Order Logic Tools, Ralph W. Wilkerson, Barbara A. Smith

Computer Science Faculty Research & Creative Works

An automated circuit diagnostic tool implementing R. Reiter's theory of diagnosis (1987) based on deep knowledge (i.e. knowledge based on certain design information) and using first-order logic as the representation language is discussed. In this approach, the automated diagnostician uses a description of the system structure and observations describing its performance to determine if any faults are apparent. If there is evidence that the system is faulty, the diagnostician uses the system description and observations to ascertain which component(s) would explain the behavior. In particular, Reiter's method finds all combinations of components which explain this behavior.


Reliable Distributed Sorting Through The Application-Oriented Fault Tolerance Paradigm, Bruce M. Mcmillin, L. M. Ni Jan 1989

Reliable Distributed Sorting Through The Application-Oriented Fault Tolerance Paradigm, Bruce M. Mcmillin, L. M. Ni

Computer Science Faculty Research & Creative Works

The design and implementation of a reliable version of the distributed bitonic sorting algorithm using the application-oriented fault tolerance paradigm on a commercial multicomputer is described. Sorting assertions in general are discussed and the bitonic sort algorithm is introduced. Faulty behavior is discussed and a fault-tolerant parallel bitonic sort developed using this paradigm is presented. The error coverage and the response of the fault-tolerant algorithm to faulty behavior are presented. Both asymptotic complexity and the results of run-time experimental measurements on an Ncube multicomputer are given. The authors demonstrate that the application-oriented fault tolerance paradigm is applicable to problems of …


A Definition Optimization Technique Used In A Code Translation Algorithm, David M. Dejean, George Winston Zobrist Jan 1989

A Definition Optimization Technique Used In A Code Translation Algorithm, David M. Dejean, George Winston Zobrist

Computer Science Faculty Research & Creative Works

Data flow analysis is used to optimize variable definitions in a program that translates microprocessor object code to a higher order language. © 1989, ACM. All rights reserved.


Personal Computing For The Visually Impaired, Bruce M. Mcmillin, P. Y. Mcmillin Jan 1989

Personal Computing For The Visually Impaired, Bruce M. Mcmillin, P. Y. Mcmillin

Computer Science Faculty Research & Creative Works

The problem of providing feedback from the computer to a visually impaired user is examined. The use of traditional tactile input and output (Braille) is described. The limitations of voice output are discussed, and difficulties posed by complicated screen formats and screen review are considered.


Automated Circuit Diagnosis Using First Order Logic Tools, Barbara Smith, Ralph W. Wilkerson, Gerald E. Peterson, Mcdonnell Douglas Jun 1988

Automated Circuit Diagnosis Using First Order Logic Tools, Barbara Smith, Ralph W. Wilkerson, Gerald E. Peterson, Mcdonnell Douglas

Computer Science Faculty Research & Creative Works

While Numerous Diagnostic Expert Systems Have Been Successfully Developed in Recent Years, They Are Almost Uniformly based on Heuristic Reasoning Techniques (I.e., Shallow Knowledge) in the Form of Rules. This Paper Reports on an Automated Circuit Diagnostic Tool based on Reiter's Theory of Diagnosis. in Particular, this is a Theory of Diagnosis based on Deep Knowledge (I.e., Knowledge based on Certain Design Information) and using First Order Logic as the Representation Language. the Inference Mechanism Which is Incorporated as Part of the Diagnostic Tool is a Refutation based Theorem Prover using Rewriting Systems for Boolean Algebra Developed by Hsiang. Consequently, …


Implementation Of Cross Intersection Between Triangular Surfaces, Chaman Sabharwal, Thomas G. Melson Feb 1988

Implementation Of Cross Intersection Between Triangular Surfaces, Chaman Sabharwal, Thomas G. Melson

Computer Science Faculty Research & Creative Works

No abstract provided.


An Inherently Parallel Large Grained Data Flow Environment, Roger E. Eggen, John R. Metzner Feb 1988

An Inherently Parallel Large Grained Data Flow Environment, Roger E. Eggen, John R. Metzner

Computer Science Faculty Research & Creative Works

A parallel programming environment based on data flow is described. Programming in the environment involves use with an interactive graphic editor which facilitates the construction of a program graph consisting of modules, ports, paths and triggers. Parallelism is inherent since data presence allows many modules to execute concurrently. The graph is executed directly without transformation to traditional representations. The environment supports programming at a very high level as opposed to parallelism at the individual instruction level.


Executable Assertion Development For The Distributed Parallel Environment, Bruce M. Mcmillin, L. M. Ni Jan 1988

Executable Assertion Development For The Distributed Parallel Environment, Bruce M. Mcmillin, L. M. Ni

Computer Science Faculty Research & Creative Works

The use of executable assertions is a powerful tool with which to perform program verification, provide software fault-tolerance, and provide hardware fault-tolerance via the application-oriented paradigm. The authors show that assertions commonly used in the sequential programming environment are inadequate for the distributed parallel environment. In particular, it is shown that even design-based assertions are myopic and provide inadequate error coverage. In their place, a triad of basic metrics is proposed for certain classes of problems that, when applied beginning with the specification phase of the life cycle, produce assertions that are better suited to the parallel environment. This method …


A Routing Algorithm For Three Stage Rearrangeable Clos Networks, Ralph W. Wilkerson Feb 1987

A Routing Algorithm For Three Stage Rearrangeable Clos Networks, Ralph W. Wilkerson

Computer Science Faculty Research & Creative Works

No abstract provided.


A Logic Programming Model Of The Game Of Sprouts, Ralph M. Butler, Selden Y. Trimble, Ralph W. Wilkerson Feb 1987

A Logic Programming Model Of The Game Of Sprouts, Ralph M. Butler, Selden Y. Trimble, Ralph W. Wilkerson

Computer Science Faculty Research & Creative Works

The Game of Sprouts Has Intrigued Mathematicians for Nearly Twenty Years. This Paper Describes a Representation Scheme Which Simplifies Much of the Geometry of the Game. using This Representation, We Develop a Prolog Program Which Will Play Sprouts. It is Hoped that the Program Will Prove to Be a Useful Research Tool in Finding the Key to a Winning Strategy for Sprouts and that the Representation Will Serve as a Useful Model for Studying Planar Graphs.


A Logic Programming Model Of The Game Of Sprouts, Ralph M. Butler, Selden Y. Trimble, Ralph W. Wilkerson Feb 1987

A Logic Programming Model Of The Game Of Sprouts, Ralph M. Butler, Selden Y. Trimble, Ralph W. Wilkerson

Computer Science Faculty Research & Creative Works

The Game of Sprouts Has Intrigued Mathematicians for Nearly Twenty Years. This Paper Describes a Representation Scheme Which Simplifies Much of the Geometry of the Game. using This Representation, We Develop a Prolog Program Which Will Play Sprouts. It is Hoped that the Program Will Prove to Be a Useful Research Tool in Finding the Key to a Winning Strategy for Sprouts and that the Representation Will Serve as a Useful Model for Studying Planar Graphs. © 1987, ACM. All Rights Reserved.


Prolog., Ralph W. Wilkerson Jan 1986

Prolog., Ralph W. Wilkerson

Computer Science Faculty Research & Creative Works

A Description is Given of Prolog, a Contraction of Programming in Logic, Which Uses the Formalism of Mathematical Logic as its Primary Design Principle. the Structure of Prolog is Examined, and a Database Program is Described to Illustrate its application. an Application to an Artificial Intelligence Problem, the Towers of Hanoi, is Also Given.