ppxscal/embedding_network huggingface dataset:
A TAXONOMY OF RACE DETECTION ALGORITHMS
Authors: D. P. Helmbold, C. E. McDowell
Venue:  (1994)

This paper presents a taxonomy that categorizes methods for determining event orders in executions of parallel programs. These event orderings can then be used to detect race conditions in parallel programs. The paper also shows how recent race results fit into the event ordering taxonomy, and presents some new results for previously unexamined points in the taxonomy.
Errors and Perturbations in Vandermonde Systems
Authors: James M. Varah
Venue:  (1990)

The Bjorck-Pereyra algorithm for Vandermonde systems is known to produce extremely accurate results in some cases, even when the matrix is very ill-conditioned. Recently, Higham has produced an error analysis of the algorithm which identifies when this behaviour will take place. In this paper, we observe that this analysis also predicts the error behaviour very well in general, and illustrate this with a series of extensive numerical tests. Moreover, we relate the computational error to that caused by perturbations in the matrix elements, and show that they are not always commensurate. We also discuss the relationship between these error and perturbation estimates with the ``effective well-condition'''' of Chan and Foulser.
NP-Completeness of a Combinator Optimisation Problem
Authors: M. S. Joy, V. J. Rayward-Smith
Venue:  (1987)

We consider a deterministic rewrite system for combinatory logic over combinators S, K, I, B, C, S'', B'' and C''. Terms will be represented by graphs so that reduction of a duplicator will cause the duplicated expression to be "shared" rather than copied. To each normalising term we assign a weighting which is the number of reduction steps necessary to reduce the expression to normal form. A lambda expression may be represented by several distinct expressions in combinatory logic, and two combinatory logic expressions are considered equivalent if they represent the same lambda expression (up to beta-eta-equivalence). The problem of minimising the number of reduction steps over equivalent combinator expressions (i.e. the problem of finding the "fastest running" combinator representation for a specific lambda expression) is proved to be NP-complete by reduction from the "Hitting Set" problem.
BDD vs. Constraint-Based Model Checking: An Experimental Evaluation for Asynchronous Concurrent Systems
Authors: T. Bultan
Venue:  (1999)

BDD-based symbolic model checking has been applied to a wide range of applications. Recently, constraint-based approaches, which use arithmetic constraints as a symbolic representation, have been used in symbolic model checking of infinite-state systems. We argue that use of constraint-based model checking is not limited to infinite-state systems. It can also be an efficient alternative to BDD-based model checking for systems with integer variables that have large domains. In this paper we compare the performance of BDD-based model checker SMV to the performance of our constraint-based model checker on verification of several asynchronous concurrent systems. The results indicate that constraint-based model checking is a viable option for verification of asynchronous concurrent systems that require more than 5 boolean variables to encode each integer variable. The ACM Portal is published by the Association for Computing Machinery. Copyright © 2010 ACM, Inc. Terms of Usage Privacy Policy Code of Ethics Contact Us Useful downloads: Adobe Acrobat QuickTime Windows Media Player Real Player
Labeling Schemes for Flow-Related Functions
Authors: M. Katz, N. A. Katz, D. Peleg
Venue:  (2000)

This paper studies labeling schemes for flow, connectivity and related functions. A flow labeling scheme using O(logn?log[^(w)])-bit labels is presented for general n-vertex graphs with maximum (integral) capacity [^(w)]. This is shown to be asymptotically optimal, by establishing a lower bound of O(logn?log[^(w)]) for the required label size over the class of n-vertex trees with maximum capacity [^(w)]. For edge-connectivity, this yields a tight bound of Q(log2 n). In addition, an f labeling scheme over trees is designed for a wide class of functions f, referred to as semigroup functions.
STAR: Secure Real-Time Transaction Processing with Timeliness Guarantees
Authors: K. D. Kang, S. H. Son, J. A. Stankovic
Venue:  (2002)

Real-time databases are needed in security-critical applications, e.g., e-commerce, agile manufacturing, and military applications. In these applications, transactions and data items can be classified into several security levels according to their clearance and sensitivity levels. It is essential for real-time databases to prevent illegal direct/indirect transfer of sensitive data, e.g., secret trade, manufacturing, or operational data, between transactions belonging to different security levels. Further, transactions should be committed within their deadlines, i.e., before the market, manufacturing, or battle field status changes. In this paper, we present a novel real-time database architecture, in which illegal direct/indirect inter-level information flows are prevented while controlling the deadline miss ratio for admitted transactions to remain below a certain threshold. In our approach, mandatory access control mechanisms are applied for security purposes. QoS management, admission control, and feedback control schemes are applied to support certain guarantees on miss ratio against potential overload and data conflicts. A detailed simulation study shows that our approach can support the specified miss ratio preventing illegal information flows even in the presence of unpredictable workloads and varying degrees of data contention, whereas baseline approaches fail.
Modeling Concepts for Workflow Specification
Authors: Markus Kradolfer, Andreas Geppert
Venue:  (1997)

This paper describes modeling concepts for the specification of processing entities and workflows and a workflow execution model for the TRAMs project.
BLP: Applying ILP Techniques to Bytecode Execution
Authors: Kevin Scott, Kevin Skadron
Venue:  (2000)

The popularity of Java has resulted in a flurry of engineering and research activity to improve performance of Java Virtual Machine (JVM) implementations. This paper introduces the concept of bytecode-level parallelism (BLP)--data- and control- independent bytecodes that can be executed concurrently--as a vehicle for achieving substantial performance improvements in implementations of JVMs, and describes a JVM architecture--JVM-BLP--that uses threads to exploit BLP. Measurements for several large Java programs show levels of BLP can be as high as 14.564 independent instructions, with an average of 6.768.
Publishing evolving metadocuments on the web
Authors: Andruid Kerne, Madhur Khandelwal, Vikram Sundaram
Venue: Proceedings of the fourteenth ACM conference on Hypertext and hypermedia (2003)

Metadocuments are documents that consist primarily of references to other documents, and elements within them. Our active browsing web visualization tool generates an evolving series of navigable metadocument snapshots over time. The granularity of browsing is shifted, from documents to the finer grained information elements, which are metadocument constituents. The program conducts expression-directed automatic retrieval of information from the web. It performs procedural visual composition of the information elements to form spatial hypertext. The user can express interest and design intentions through direct manipulation interactions with the visualized information elements. As prior versions of the tool lacked the capabilities of save and load, they were entirely process-oriented. The metadocuments existed only as transient states. This paper is an early report on our new metadocument authoring and publishing capability, and its potential uses. Saved metadocuments can be published on the web. Once published, they can serve both as static navigable metadocuments, and as the jumping off point from which the information space represented by the collected elements can continue to evolve.
Juggling Networks
Authors: Nicholas Pippenger
Venue:  (1993)

Switching networks of various kinds have come to occupy a prominent position in computer science as well as communication engineering. The classical switching network technology has been space-division-multiplex switching, in which each switching function is performed by a spatially separate switching component (such as a crossbar switch). A recent trend in switching network technology has been the advent of time-division-multiplex switching, wherein a single switching component performs the function of many switches at successive moments of time according to a periodic schedule. This technology has the advantage that nearly all of the cost of the network is in inertial memory (such as delay lines), with the cost of switching elements growing much more slowly as a function of the capacity of the network. In order for a classical space-division-multiplex network to be adaptable to time-division-multiplex technology, its interconnection pattern must satisfy stringent requirements. For example, networks based on randomized interconnections (an important tool in determining the asymptotic complexity of optimal networks) are not suitable for time-division-multiplex implementation. Indeed, time-division-multiplex implementations have been presented for only a few of the simplest classical space-division-multiplex constructions, such as rearrangeable connection networks. This paper shows how interconnection patterns based on explicit constructions for expanding graphs can be implemented in time-division-multiplex networks. This provides time-division-multiplex implementations for switching networks that are within constant factors of optimal in memory cost, and that have asymptotically more slowly growing switching costs. These constructions are based on a metaphor involving teams of jugglers whose throwing, catching and passing patterns result in intricate permutations of the balls. This metaphor affords a convenient visualization of time-division-multiplex activities that should be of value in devising networks for a variety of switching tasks.
Publish and Subscribe with Reply
Authors: Jonathan C. Hill, John C. Knight, Aaron M. Crickenberger, Richard Honhard
Venue:  (2002)

Reply for Publish and Subscribe allows receivers of a publication to reply to the publisher. We demonstrate that Reply is a natural, efficient, and useful component of Publish/Subscribe. It is natural because it maintains the weakest possible coupling between senders and receivers. It is efficient because it stores computations discarded in publication forwarding, later applying them to channel replies. Most importantly, it is useful because it increases the domain of applications for which Publish/Subscribe is suited. This paper includes discussion of Replys utility, introduction of two algorithms with differing state storage and capabilities, their analysis for worst-case conditions, modeling of required resources, and presentation of a modular implementation of Reply for distributed Publish/Subscribe systems.
Using MMX Technology in Digital Image Processing
Authors: Vladimir Kravtchenko
Venue:  (1998)

MMX technology is designed to accelerate multimedia and communications applications. The technology includes new processor instructions and data types and exploits the parallelism in processing multiple data. In this work we demonstrate how to use MMX technology in digital image processing applications and discuss important aspects of practical implementation with the GCC compiler. We also focus on the experimental results of common image processing operations and provide a comparative performance analysis.
StarBase Research Summary, Autumn 1994
Authors: Matthew R. Lehr, Sang H. Son
Venue:  (1994)

This report describes the research activities pertaining to the StarBase project at the University of Virginia''s Department of Computer Science. StarBase, a firm real-time database management system (RT-DBMS), is remarkable in that it is constructed on top of an actual real-time microkernel. StarBase seeks to provide a general RT-DBMS environment which can handle a variable transac tion load, rather than statically scheduling a known set of transactions. This report presents an overview of the StarBase RT-DBMS as it operates today and describes its development environment. The accomplishments of the last two years of research are reviewed and the critical features needed to support such a RT-DBMS are examined.
A New Adaptive GMRES Algorithm for Achieving High Accuracy
Authors: Sosonkina Maria, Watson Layne T., Kapania Rakesh K.
Venue:  (1996)

GMRES(k) is widely used for solving nonsymmetric linear systems. However, it is inadequate either when it converges only for k close to the problem size or when numerical error in the modified Gram-Schmidt process used in the GMRES orthogonalization phase dramatically affects the algorithm performance. An adaptive version of GMRES(k) which tunes the restart value k based on criteria estimating the GMRES conversion rate for the given problem is proposed here. This adaptive GMRES(k) procedure outperforms standard GMRES(k), several other GMRES-like methods, and QMR on actual large scale sparse structural mechanics postbuckling and analog circuit simulation problems. There are some applications, such as homotopy methods for high Reynolds number viscous flows, solid mechanics postbuckling analysis, and analog circuit simulation, where very high accuracy in the linear system solutions is essential. In this context, the modified Gram-Schmidt process in GMRES can fail causing the entire GMRES iteration to fail. It is shown that the adaptive GMRES(k) with the orthogonalization performed by Householder transformations succeeds whenever GMRES(k) with the orthogonolization performed by the modified Gram-Schmidt process fails, and the extra cost of computing Householder transformations is justified for these applications.
Business modelling with UML: distilling directions for future research
Authors: Sergio de Cesare, Mark Lycett, Dilip Patel
Venue: Enterprise information systems IV (2003)

The Unified Modelling Language (UML) was originally conceived as a general-purpose language capable of modelling any type of system and has been used in a wide range of domains. However, when modelling systems, the adoption of domain-specific languages can enable and enhance the clarity, readability and communicability amongst modellers of the same domain. The UML provides support for extending the language for defining domain-specific meta-elements. This paper approaches the UML from a business perspective and analyses its potential as a business modelling language. The analysis proceeds along two complementary paths: a critical study of UML diagrams and a description of UML extensibility mechanisms for the definition of a business profile.
SPRAY RENDERING: A NEW FRAMEWORK FOR VISUALIZATION
Authors: Alex Pang, Kyle Smith
Venue:  (1993)

We propose a new framework for doing scientific visualization that allows the users to freely explore their data set. This framework uses a metaphorical abstraction of a virtual can of spray paint that can be used to render data sets and make them visible. Different cans of spray paint may be used to color the data differently. Different types of spray paint may also be used to highlight different features in the data set. To achieve this, individual paint particles are endowed with intelligent behavior. This idea offers several advantages over existing methods: (1) it generalizes the current techniques of surface, volume and flow visualization under one coherent framework; (2) it works with regular and irregular grids as well as sparse and dense data sets; (3) it allows selective progressive refinement and can be implemented on parallel architectures in a straight forward manner; (4) it is modular, extensible and provides scientists with the flexibility for exploring relationships in their data sets in natural and artistic ways.
Removing Unnecessary Synchronization in Java
Authors: Jeff Bogda, Urs Holzle
Venue:  (1999)

Java programs perform many synchronization operations on data structures. Some of these synchronizations are unnecessary; in particular, if an object is reachable only by a single thread, concurrent access is impossible and no synchronization is needed. We describe a flow-insensitive, context-sensitive data-flow analysis that finds such situations and a global optimizing transformation that eliminates synchronizations on these objects. For every program in our suite of ten Java benchmarks consisting of SPECjvm98 and others, our system optimizes over 90% of the alias sets containing at least one synchronized object. As a result, the dynamic frequency of synchronizations is reduced by up to 99%. For two benchmarks that perform synchronizations very frequently, this optimization leads to speedups of 36% and 20%, respectively.
Specifying and Managing Quality of Real-Time Data Services
Authors: K. D. Kang, S. H. Son, J. A. Stankovic
Venue:  (2002)

The demand for real-time data services is increasing in many applications including e-commerce, agile manufacturing, and telecommunication network management. In these applications, it is desirable to execute transactions within their deadlines, i.e., before the real-world status changes, using fresh (temporally consistent) data. However, it is challenging to meet these fundamental requirements due to dynamic workloads and data access patterns in these applications and potential conflicts between transaction timeliness and data freshness requirements. In this paper, we define average/transient deadline miss ratio and new data freshness metrics to specify the required quality of real-time data services. We also present a novel QoS management architecture to support the required QoS even in the presence of unpredictable workloads and access patterns. To prevent overload and support the required QoS, the presented architecture applies feedback control, admission control, and flexible freshness management schemes. A simulation study shows that our QoS-aware approach can support the required QoS, whereas baseline approaches fail to support the required miss ratio and/or freshness. Further, our approach shows a comparable performance to the theoretical oracle that is privileged by a complete future knowledge of data accesses.
A Model Based on Software Quality Factors which Predicts Maintainability
Authors: Steven A. Wake, Sallie M. Henry
Venue:  (1988)

Computer scientists are continually attempting to improve software system development. Systems are developed in a top-down fashion for better modularity and understandability. Performance enhancements are implemented for more speed. One area in which a great deal of effort is being devoted is software maintenance. Brooks estimates that fifty percent of the development cost of a software system is for maintenance activities [BROF82]. Since a large portion of the effort of a system is devoted to maintenance, it is reasonable to assume that driving down maintenance costs would drive down the overall cost of the system. Measuring the complexity of a software system could aid in this attempt. By lowering the complexity of the system or of subsystems within the system, it may be possible to reduce the amount of maintenance necessary. Software quality metrics were developed to measure the complexity of software systems. This study relates the complexity of the system as measured by software metrics to the amount of maintenance necessary to that system. We have developed a model which uses several software quality metrics as parameters to predict maintenance activity.
MODELING REPLICA DIVERGENCE IN A WEAK-CONSISTENCY PROTOCOL FOR GLOBAL-SCALE DISTRIBUTED DATA BASES
Authors: Richard A. Golding, Darrell D. E. Long
Venue:  (1993)

Distributed database systems for wide-area networks must scale to very large numbers of replicas in order to provide acceptable availability and response time. Weak-consistency replication protocols, such as the *timestamped anti-entropy* (TSAE) protocol we have developed, allow a database to scale to hundreds or thousands of replicas. The TSAE protocol allows updates to be processed by a single replica, then propagated from one replica to another in the background, causing replicas to temporarily diverge. The divergence is resolved in a short time and is resolved correctly even in the presence of temporary replica failure and network partition. We present a detailed analysis of the update propagation latency and the divergence between replicas caused by this protocol.
Proximity-Preserving Labeling Schemes
Authors: D. Peleg
Venue:  (1997)

This paper considers informative labeling schemes for graphs. Specifically, the question considered is whether it is possible to label the vertices of a graph with short labels in such a way that the distance between any two vertices can be inferred from inspecting their labels. It is shown that for the class of n-vertex trees, there exists such a labeling scheme using O(log2 n) bit labels. For the family of all n-vertex graphs, a labeling scheme is proposed that using O(log3 n) bit labels can provide approximate estimates to the distance, which are accurate up to a factor of O{2logn}.
AUTOMATIC PROCESS SELECTION FOR LOAD BALANCING (M.S. Thesis)
Authors: William Osser
Venue:  (1992)

Distributed operating systems give users access to multiple computational engines throughout the system network. Users of one workstation are not hindered by the CPU intensive applications run on a different workstation. However, when a large number of machines in the network are idle, the efficiency of computation is decreased. Load balancing promises to alleviate this problem by sharing the workload on heavily loaded workstations with lightly loaded workstations. A threshold can be established so that only a limited number of processes are transferred to the lightly loaded sites, so that the load at those sites does not inhibit local execution of processes. While load balancing has been studied extensively, there have been few studies on determining which processes should be relocated to increase the throughput of the system. We present an automatic process selector for load balancing that chooses processes to be relocated based on the history of its performance. We have implemented this system on the Sprite distributed operating system. The ACM Portal is published by the Association for Computing Machinery. Copyright © 2010 ACM, Inc. Terms of Usage Privacy Policy Code of Ethics Contact Us Useful downloads: Adobe Acrobat QuickTime Windows Media Player Real Player
MODELING ANIMALS WITH BONES, MUSCLES, AND SKIN
Authors: Jane Wilhelms
Venue:  (1995)

A new approach to animal modeling and animation using simulated individual bones and muscles, soft tissues, and skin is described. Bones and muscles (made of combinations of ellipsoids) can be generated automatically from a tree structure and joint geometry or designed interactively. Together with soft tissue, these provide the underlying anatomy. A polygonal skin mesh is automatically generated to form a smooth covering. Muscles stretch across joints, and their orientations, sizes, and shapes change during joint motion. The skin mesh automatically adjusts to changes in position due to the effect of neighboring skin points and anchor points associated with the underlying anatomy. Much of the process is automated; parameters may be be adjusted, and components can be added and removed. Manipulation and animation occur at comfortable interactive speeds on graphics workstations.