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Distributed Computing Systems And Checkpointing, Ken Wong, Mark Franklin Jan 1993

Distributed Computing Systems And Checkpointing, Ken Wong, Mark Franklin

All Computer Science and Engineering Research

This paper examines the performance of synchronous checkpointing in a distributed computing environment with and without load redistribution. Performance models are developed, and optimum checkpoint intervals are determined. The analysis extends earlier work by allowing for multiple nodes, state dependent checkpoint intervals, and a performance metric which is coupled with failure-free performance and the speedup functions associated with implementation of parallel algorithms. Expressions for the optimum checkpoint intervals for synchronous checkpointing with and without load redistribution are derived and the results are then used to determine when load redistribution is advantageous.

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Learning Unions Of Boxes With Membership And Equivalence Queries, Paul W. Goldberg, Sally A. Goldman, H. David Matthias Jan 1993

Learning Unions Of Boxes With Membership And Equivalence Queries, Paul W. Goldberg, Sally A. Goldman, H. David Matthias

All Computer Science and Engineering Research

We present two algorithms that use membership and equivalence queries to exactly identify the concepts given by the union of s discretized axis-parallel boxes in d-dimensional discretized Euclidean space where each coordinate can have n discrete values. The first algorithm receives at most s*d counterexamples and uses time and membership queries polynomial in s and logn for d any constant. Further, all equivalence queries made can be formulated as the union of O(s*d*log(s)) axis-parallel boxes. Next, we introduce a new complexity measure that better captures the complexity of a union of boxes than simply the number of boxes and dimensions. …

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Fril - A Fractal Intermediate Language, Ron Cytron, David Shields Jan 1993

Fril - A Fractal Intermediate Language, Ron Cytron, David Shields

All Computer Science and Engineering Research

This document describes the motivation, language description, and experience using FrIL, an intermediate language for a compiler's "middle-end." FrIL has subbessfully supported a two-semester compiler construction sequence, where the first semester included code generation from a C-like language and the second semester included advanced data flow analysis and program transformation.

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The Pessimism Behind Optimistic Simulation, George Varghese, Roger D. Chamberlain, William E. Weihl Jan 1993

The Pessimism Behind Optimistic Simulation, George Varghese, Roger D. Chamberlain, William E. Weihl

All Computer Science and Engineering Research

In this paper we make an analogy between the time that storage must be maintained in an optimistic simulation and the blocking time in a conservative simulation. By exploring this analogy, we design two new Global Virtual Time (GVT) protocols for Time Warp systems. The first simple protocol is based on the null message scheme proposed for clock advancement in some conservative approaches; this yields what we call Local Guaranteed Time. Our main contribution is a second new protocol that is inspired by Misra's circulating marker scheme for deadlock recovery in conservative simulations, and appears to have advantages over previous …

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Research Proposal: Preference Acquisition Through Reconciliation Of Inconsistencies, Nilesh L. Jain Jan 1993

Research Proposal: Preference Acquisition Through Reconciliation Of Inconsistencies, Nilesh L. Jain

All Computer Science and Engineering Research

The quality of performance of a decision-support system (or an expert system) is determined to a large extent by its underlying preference model (or knowledge base). The difficulties in preference and knowledge acquisition make them a major focus of current research in decision-support and expert systems. Researchers have used various concepts to develop promising acquisition techniques. One of the concepts used is knowledge maintenence where the knowledge base is changed in response to incorrect or inadequate performance by the expert system. This dissertation investigates a preference acquisition technique based on the reconciliation of inconsistencies between the preference model and the …

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Logical Interference In Symmetric Connectionist Networks, Gadi Pinkas Jan 1993

Logical Interference In Symmetric Connectionist Networks, Gadi Pinkas

All Computer Science and Engineering Research

This work delineates the relation between logic and symmetric neural networks. The motivation is two-fold: 1) to study the capabilities and limitations of connectionist networks with respect to knowledge representatoin; and 2) to develop a new kind of inference negine that is expressive, massively parallel, capable of coping with nonmonotonic or noisy knowledge and capable of learning. The thesis shows that propositional logic can be implemented efficiently in networks where hidden units allow the representation of arbitrary constraints. An inference engine is constructed which can obtain its knowledge either by compiling symbolic rules or by learning them inductively from examples. …

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A Comparison Study Of The Pen And The Mouse In Editing Graphic Diagrams, Ajay Apte, Takayuki Dan Kimura Jan 1993

A Comparison Study Of The Pen And The Mouse In Editing Graphic Diagrams, Ajay Apte, Takayuki Dan Kimura

All Computer Science and Engineering Research

We report the results of an experiment comparing the merits of the pen and the mouse as drawing devices. For this study a pen-based graphic diagram editor equipped with a shape recognition algorithm was developed on GO's PenPoint operating system. A commercially available drawing program on NeXT was used for mouse-based editing. Twelve CS students were chosen as subjects and asked to draw four different diagrams of similar complexity: two with a pen and the other two with a mouse. The diagrams are chosen from the categories of dataflow visual language, Petri nets, flowcharts, and state diagrams. The results indicate …

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A Taxonomy Of Program Visualization Systems, Gruia-Catalin Roman, Kenneth C. Cox Jan 1993

A Taxonomy Of Program Visualization Systems, Gruia-Catalin Roman, Kenneth C. Cox

All Computer Science and Engineering Research

Program visualization may be viewed as a mapping from programs to graphical representations. This simple idea provides a formal framework for a new taxonomy of program visualization systems. The taxonomy is compared briefly against previous attempts to organize the program visualization field. The taxonomic principles and their motivation are explained in detail with reference to a number of existing systems, especially Balsa, Tango, and Pavane.

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Efficiently Computing {Phi}-Nodes On-The-Fly, Ron K. Cytron, Jeanne Ferrante Jan 1993

Efficiently Computing {Phi}-Nodes On-The-Fly, Ron K. Cytron, Jeanne Ferrante

All Computer Science and Engineering Research

Recently, Static Single Assignment Form and Sparse Evaluation Graphs have been advanced for the efficient solution of program optimization problems. Each method is provided with an initial set of flow graph nodes that inherently affect a problem's solution. Other relevant nodes are those where potentially disparate solutions must combine. Previously, these so-called {phi}-nodes were found by computing the iterated dominance frontiers of the initial set of nodes, a process that could take worst case quadratic time with respect to the input flow graph. In this paper we present an almost-linear algorithm for detemining exactly the same set of {phi}-nodes.

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The Study Of Computer Science Concepts Through Game Play, Benjamin M. Weber Jan 1993

The Study Of Computer Science Concepts Through Game Play, Benjamin M. Weber

All Computer Science and Engineering Research

No abstract provided.

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Segmentation/Recognition Of Hand-Written Numeral Characters, Khalid Sherdil Jan 1993

Segmentation/Recognition Of Hand-Written Numeral Characters, Khalid Sherdil

All Computer Science and Engineering Research

This thesis describes a number of techniques for segmenting non-cursive handwritten digits into individual characters. It strongly emphasizes on a recognition-segmentation algorithm, which uses the linear regression method to recognize those strokes which consist of one or more straight-lined parts. A new method of sampling the pen data according to the pen speed, hence giving a more uniform points concentratino distribution, is also introduced. It is shown how several of our segmenting techniques, such as relative stroke lengths, relative stroke positions, order of stroke entry, stroke direction, stroke intersection, etc. can be combined to yield success results of about 95%.

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The Programmers' Playground: I/O Abstraction For Heterogeneous Distributed Systems, Kenneth J. Goldman, Michael D. Anderson, Bala Swaminathan Jan 1993

The Programmers' Playground: I/O Abstraction For Heterogeneous Distributed Systems, Kenneth J. Goldman, Michael D. Anderson, Bala Swaminathan

All Computer Science and Engineering Research

I/O abstraction is offered as a new high-level approach to interprocess communication. Functional components of a concurrent system are written as encapsulated modules that act upon local data structures, some of which may be published for external use. Relationships among modules are specified by logical connections among their published data structures. Whenever a module updates published data, I/O takes place implicitly according to the configuration of logical connections. The Programmer's Playground, a software library and run-time system supporting I/O abstraction, is described. Design goals include high-level communication among programs written in multiple programming languages and the uniform treatment of discrete …

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Real-Time Admission Control Algorithms With Delay And Loss Guarantees In Atm Networks, Apostolos Dailianas, Andreas D. Bovopoulos Jan 1993

Real-Time Admission Control Algorithms With Delay And Loss Guarantees In Atm Networks, Apostolos Dailianas, Andreas D. Bovopoulos

All Computer Science and Engineering Research

A multimedia ATM network is shared by media streams with different performance requirements. For media streams such as file transfers, the preservation of bursts and the provision of guarantees for loss probability at the burst level is of primary importance, while, for media streams such as voice, loss guarantees at the cell level are sufficient. Continuous media have stringent delay jitter requirements. Finally, some applications require loss-free transmission. In this paper, the first complete traffic management scheme for multimedia ATM networks is introduced. The traffic management scheme supports four different classes of traffic, each of which has different performance requirements …

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Reasoning About Synchrony Illustrated On Three Models Of Concurrency, Gruia-Catalin Roman, Jerome Plun Jan 1993

Reasoning About Synchrony Illustrated On Three Models Of Concurrency, Gruia-Catalin Roman, Jerome Plun

All Computer Science and Engineering Research

This paper presents a model of concurrency (Dynamic Synchrony) whose distinctive feature is a novel formal treatment of synchronization. Synchrony is defined as the coordinated execution of two or more actions. The dynamic aspect comes from the fact that the definition of which actions must be executed synchronously can change freely during the execution of the program. This unique modeling capability comes with a UNITY-stype assertional logic that can be applied to program verification and derivation. This paper shows that the proposed proof logic can be used to verify programs expressed using other models of foncurrency without having to translate …

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Clothespins On Timelines: Utilities And The Interval Representation Of Time, R. P. Loui, Jersey Chen Jan 1993

Clothespins On Timelines: Utilities And The Interval Representation Of Time, R. P. Loui, Jersey Chen

All Computer Science and Engineering Research

We discuss the problem of representing utility in planning systems that are based on Allen's [83] popular ontology for planning, which represents actions and events as time intervals. We identify a small number of primitive functions on time intervals which may be helpful in representing preference and also in eliminating dominated actions. Assuming that utility can be decomposed to take advantage of these primitives, these functions provide one solution to the problem of specifying utility in such expressive planning languages. We identify a restricted class of utility expressions that generate linear programming problems. The contribution is not deep, but is …

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Asking Questions To Minimize Errors, Nader H. Bshouty, Sally A. Goldman, Thomas R. Hancock, Sleiman Matar Jan 1993

Asking Questions To Minimize Errors, Nader H. Bshouty, Sally A. Goldman, Thomas R. Hancock, Sleiman Matar

All Computer Science and Engineering Research

A number of efficient learning algorithms achieve exact identification of an unknown function from some clas using membership and equivalence queries. Using a standard transformation such algorithms can easily be converted to on-line learning algorithms that use membership queries. Under such a transformation the number of equivalence queries made by the query algorithm directly corresponds to the number of mistakes made by the on-line algorithm. In this paper we consider several of the natural classes known to be learnable in this setting, and investigate the minimum number of equivalence queries with accompanying counterexamples (or equivalently the minimum number of mistakes …

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A Study Of Dynamic Optimization Techniques: Lessons And Directions In Kernel Design, Calton Pu, Jonathan Walpole Jan 1993

A Study Of Dynamic Optimization Techniques: Lessons And Directions In Kernel Design, Calton Pu, Jonathan Walpole

Computer Science Faculty Publications and Presentations

The Synthesis kernel [21,22,23,27,28] showed that dynamic code generation, software feedback, and fine-grain modular kernel organization are useful implementation techniques for improving the performance of operating system kernels. In addition, and perhaps more importantly, we discovered that there are strong interactions between the techniques. Hence, a careful and systematic combination of the techniques can be very powerful even though each one by itself may have serious limitations. By identifying these interactions we illustrate the problems of applying each technique in isolation to existing kernels. We also highlight the important common under-pinnings of the Synthesis experience and present our ideas on …

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Computer Model For Predicting Aids Among Intravenous Drug Users, Daniel Berleant, R. Ron Goforth, Jun Yuan Jan 1993

Computer Model For Predicting Aids Among Intravenous Drug Users, Daniel Berleant, R. Ron Goforth, Jun Yuan

Journal of the Arkansas Academy of Science

Intravenous drug abuse (IVDA) is an important cause of HIV transmission. Computer simulation is one way to understand and predict the spread of HIV infection among IVDAs. We design and simulate HIV infection among IVDAs and the impact of AIDS on this community, and thereby predict future IVDA population, HIV levels, AIDS levels, and AIDS deaths in this group. The HIV to AIDS, and AIDS to Death latencies are described by probability density functions (PDFs) in this model. Factors such as the recruit, quit, and normal death rate of IVDAs, are considered, as well as the infection and removal rates …

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Design And Implementation Of Fuzzy Logic Controllers. Thesis Final Report, 27 July 1992 - 1 January 1993, Osama A. Abihana, Oscar R. Gonzalez Jan 1993

Design And Implementation Of Fuzzy Logic Controllers. Thesis Final Report, 27 July 1992 - 1 January 1993, Osama A. Abihana, Oscar R. Gonzalez

Electrical & Computer Engineering Faculty Publications

The main objectives of our research are to present a self-contained overview of fuzzy sets and fuzzy logic, develop a methodology for control system design using fuzzy logic controllers, and to design and implement a fuzzy logic controller for a real system. We first present the fundamental concepts of fuzzy sets and fuzzy logic. Fuzzy sets and basic fuzzy operations are defined. In addition, for control systems, it is important to understand the concepts of linguistic values, term sets, fuzzy rule base, inference methods, and defuzzification methods. Second, we introduce a four-step fuzzy logic control system design procedure. The design …

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Improving The Speed Of A Distributed Checkpointing Algorithm, Sachin Garg, Kenneth F. Wong Jan 1993

Improving The Speed Of A Distributed Checkpointing Algorithm, Sachin Garg, Kenneth F. Wong

All Computer Science and Engineering Research

This paper shows how Koo and Toueg's distributed checkpointing algorithm can be modified so as to substantially reduce the average message volume. It attempts to avoid O(n{squared}) messages by using dependency knowledge to reduce the number of checkpoint request messages. Lemmas on consistency and termination are also included.

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Trainrec: A System For Training Feedforward & Simple Recurrent Networks Efficiently And Correctly, Barry L. Kalman, Stan C. Kwasny Jan 1993

Trainrec: A System For Training Feedforward & Simple Recurrent Networks Efficiently And Correctly, Barry L. Kalman, Stan C. Kwasny

All Computer Science and Engineering Research

TRAINREC is a system for training feedforward and recurrent neural networks that incorporates several ideas. It uses the conjugate-gradient method which is demonstrably more efficient than traditional backward error propagation. We assume epoch-based training and derive a new error function having several desirable properties absent from the traditional sum-of-squared-error function. We argue for skip (shortcut) connections where appropriate and the preference for a sigmoidal yielding values over the [-1,1] interval. The input feature space is often over-analyzed, but by using singular value decomposition, input patterns can be conditioned for better learning often with a reduced number of input units. Recurrent …

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An Optimal Nonblocking Multicast Virtual Circuit Switch, Jonathan S. Turner Jan 1993

An Optimal Nonblocking Multicast Virtual Circuit Switch, Jonathan S. Turner

All Computer Science and Engineering Research

This paper describes an architecture for a multicast virtual circuit switch using cell recycling. This is the first nonblocking switch architecture that is optimal in both the switching network complexity and the amount of memory required for multicast address translation. Furthermore, it is optimal in the amount of effort required for multicast connection modification. This architecture makes it both technically and economically feasible to construct the large switching systems that will ultimately be needed for wide scale deployment of Broadband ISDN to residential users. In particular, we estimate that systems with tens of thousands of 620 Mb/s ports can be …

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A Unified Model For Shared-Memory And Message-Passing Systems, Kenneth Goldman, Katherine Yelick Jan 1993

A Unified Model For Shared-Memory And Message-Passing Systems, Kenneth Goldman, Katherine Yelick

All Computer Science and Engineering Research

A unified model of distributed systems that accomodates both shared-memory and message-passing communication is proposed. An extension of the I/O automaton model of Lynch and Tuttle, the model provides a full range of types of atomic accesses to shared memory, from basic reads and writes to read-modify-write. In addition to supporting the specification and verification of shared memory algorithms, the unified model is particularly helpful for proving correspondences between atomic shared objects and invocation-response systems and for proving the correctness of systems that contain both message passing and shared memory (such as a network of shared-memory multiprocessors or a distributed …

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Symphony: A Hardware, Operating System, And Protocol Processing Architecture For Distributed Multimedia Applications, Andreas D. Bovopoulos, R. Gopalakrishnan, Saied Hosseini Jan 1993

Symphony: A Hardware, Operating System, And Protocol Processing Architecture For Distributed Multimedia Applications, Andreas D. Bovopoulos, R. Gopalakrishnan, Saied Hosseini

All Computer Science and Engineering Research

This paper explores the architectural requirements for computers to be able to process multimedia data streams such as video and audio. The I/O subsystem is shown to be a bottleneck, and a network backplane approach is suggested to alleviate this. The need to provide end-to-end performance guarantees requires predictable performance of intra-machine communication, and a schedulable bus with reservation is proposed to achieve this. In addition this requires operating system (OS) mechanisms to negotiate and enforce QoS requirements of applications. A real-time microkernel executive is proposed for each autonomous unit. Requirements for real-time microkernel exeutive is proposed for each autonomous …

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Intel Nx To Pvm 3.2 Message Passing Conversion Library, Trey Arthur, Michael L. Nelson Jan 1993

Intel Nx To Pvm 3.2 Message Passing Conversion Library, Trey Arthur, Michael L. Nelson

Computer Science Faculty Publications

NASA Langley Research Center has developed a library that allows Intel NX message passing codes to be executed under the more popular and widely supported Parallel Virtual Machine (PVM) message passing library. PVM was developed at Oak Ridge National Labs and has become the defacto standard for message passing. This library will allow the many programs that were developed on the Intel iPSC/860 or Intel Paragon in a Single Program Multiple Data (SPMD) design to be ported to the numerous architectures that PVM (version 3.2) supports. Also, the library adds global operations capability to PVM. A familiarity with Intel NX …

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A Comparison Of Queueing, Cluster And Distributed Computing Systems, Joseph A. Kaplan, Michael L. Nelson Jan 1993

A Comparison Of Queueing, Cluster And Distributed Computing Systems, Joseph A. Kaplan, Michael L. Nelson

Computer Science Faculty Publications

Using workstation clusters for distributed computing has become popular with the proliferation of inexpensive, powerful workstations. Workstation clusters offer both a cost effective alternative to batch processing and an easy entry into parallel computing. However, a number of workstations on a network does not constitute a cluster. Cluster management software is necessary to harness the collective computing power. A variety of cluster management and queuing systems are compared: Distributed Queueing Systems (DQS), Condor, Load Leveler, Load Balancer, Load Sharing Facility (LSF - formerly Utopia), Distributed Job Manager (DJM), Computing in Distributed Networked Environments (CODINE), and NQS/Exec. The systems differ in …

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Observation Of The Charmed Baryon C+ And Measurement Of The Isospin Mass Splittings Of The C, Crawford, G.; Et Al., M. Thulasidas Jan 1993

Observation Of The Charmed Baryon C+ And Measurement Of The Isospin Mass Splittings Of The C, Crawford, G.; Et Al., M. Thulasidas

Research Collection School Of Computing and Information Systems

No abstract provided.

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Exact Dominance Without Search In Decision Trees, Nilesh L. Jain, Ronald P. Loui Dec 1992

Exact Dominance Without Search In Decision Trees, Nilesh L. Jain, Ronald P. Loui

All Computer Science and Engineering Research

In order to improve understanding of how planning and decision analysis relate, we propose a hybrid model containing concepts from both. This model is comparable to [Hartman90], with slightly more detail. Dominance is simple concept in decision theory. In a restricted version of our model, we give conditions under which dominance can be detected without search: that is, it can be used as a pruning strategy to avoid growing large trees. This investigation follows the lead of [Wellman87]. The conditions seem hard to meet, but may nevertheless be useful in forward-chaining situations without focus, such as [Breese87]. It may be …

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Efficient Accommodation Of May-Alias Information In Ssa Form, Ron Cytron, Reid Gershbein Dec 1992

Efficient Accommodation Of May-Alias Information In Ssa Form, Ron Cytron, Reid Gershbein

All Computer Science and Engineering Research

We present an algorithm for incrementally including may-alias information into Static Single Assignment form by computing a sequence of increasingly precise (and correspondingly larger) partial SSA forms. Our experiments show significant speedup of our method over exhaustive use of may-alias information, as optimization problems converge well before most may-aliases are needed.

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Solution To A Multicriteria Aircraft Routing Problem Utilizing Parallel Search Techniques, James J. Grimm Iii Dec 1992

Solution To A Multicriteria Aircraft Routing Problem Utilizing Parallel Search Techniques, James J. Grimm Iii

Theses and Dissertations

Pilots select routes based on factors such as threats, fuel, time on target, distance, and refueling points. This is a time consuming task. This thesis presents the software engineering synthesis of a software tool, based on a parallelized A* search algorithm, to select routes. For simplicity only threats and distance are used. A centralized open list is used with one processor managing the list while the other processors perform the node expansions. This decomposition result in a dynamically load balanced system. A number of parameters are changed to study their impact on the execution time. The use of a branch …

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