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Full-Text Articles in Physical Sciences and Mathematics

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 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 …


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 …


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) …


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 …


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 …


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 …