ppxscal/embedding_network huggingface dataset:
Extensions to communicating sequential processes to allow protocol performance specification
Authors: J. J. Zic
Venue: Proceedings of the ACM workshop on Frontiers in computer communications technology (1987)

Formalisms based on Hoare's Communicating Sequential Processes (CSP) and Milner's Calculus of Communicating Systems (CCS) for verifying protocols are currently being used by the International Standard Organisation (ISO). However, these models need to be extended if protocol performance specification and verification is to be done, as neither of these models have timing information (other than sequencing) nor a way of specifying controlled loss of information. This paper presents two extensions to Hoare's CSP that are felt by the author to provide suitable mechanisms for specifying protocol performance. Firstly, the effects of introducing time into CSP are presented, based on the work done by Reed and Roscoe. Secondly, the traces model is modified by associating probabilities with event sequences. Finally, some example specifications are given using these two extensions.
A correctness proof for combinator reduction with cycles
Authors: William M. Farmer, John D. Ramsdell
Venue: ACM Transactions on Programming Languages and Systems (TOPLAS) (1990)

Turner popularized a technique of Wadsworth in which a cyclic graph rewriting rule is used to implement reduction of the fixed point combinator Y. We examine the theoretical foundation of this approach. Previous work has concentrated on proving that graph methods are, in a certain sense, sound and complete implementations of term methods. This work is inapplicable to the cyclic Y rule, which is unsound in this sense since graph normal forms can exist without corresponding term normal forms. We define and prove the correctness of combinator head reduction using the cyclic Y rule; the correctness of normal reduction is an immediate consequence. Our proof avoids the use of infinite trees to explain cyclic graphs. Instead, we show how to consider reduction with cycles as an optimization of reduction without cycles.
The Problems of Accuracy and Robustness in Geometric Computation
Authors: Christoph M. Hoffmann
Venue: Computer (1989)

Practical implementation of geometric operations remains error-prone, and the goal of implementing correct and robust systems for carrying out geometric computation remains elusive. The problem is variously characterized as a matter of achieving sufficient numerical precision, as a fundamental difficulty in dealing with interacting numeric and symbolic data, or as a problem of avoiding degenerate positions. The author examines these problems, surveys some of the approaches proposed, and assesses their potential for devising complete and efficient solutions. He restricts the analysis to objects with linear elements, since substantial problems already arise in this case. Three perturbation-free methods are considered: floating-point computation, limited-precision rational arithmetic, and purely symbolic representations. Some perturbation approaches are also examined, namely, representation and model, altering the symbolic data, and avoiding degeneracies.
Hardware support for distributed objects in a hypercube
Authors: J. L. Kozarek
Venue: Proceedings of the third conference on Hypercube concurrent computers and applications: Architecture, software, computer systems, and general issues - Volume 1 (1988)

A survey of parallel programs written for an experimental hypercube indicates that while systolic dataflow programs map well to a hypercube, general purpose programs with random dataflow are seriously constrained by the cost of communication. This paper proposes the augmentation of the hypercube architecture with a special-purpose communications coprocessor that provides hardware support for distributed objects. We anticipate this will increase the efficiency of inter-process communication primitives by a factor of 100.
Efficient distributed event driven simulations of multiple-loop networks
Authors: B. D. Lubachevsky
Venue: Proceedings of the 1988 ACM SIGMETRICS conference on Measurement and modeling of computer systems (1988)

Simulating asynchronous multiple-loop networks is commonly considered a difficult task for parallel programming. This paper presents two examples of asynchronous multiple-loop networks: a stylized queuing system and an Ising model. The network topology in both cases is an nX n grid on a torus. A new distributed simulation algorithm is demonstrated on these two examples. The algorithm combines three elements: 1) the bounded lag restriction, 2) precomputed minimal propagation delays, and 3) the so-called opaque periods. Theoretical performance evaluation suggests that if N processing elements (PEs) execute the algorithm in parallel and the simulated system exhibits sufficient density of events, then, in average, processing one event would require &Ogr;(logN) instructions of one PE. In practice, the algorithm has achieved substantial speed-ups: the speed-up is greater than 16 using 25 PEs on a shared memory MIMD bus computer, and greater than 1900 using 214 PEs on a SIMD computer.
Concurrent operations on extendible hashing and its performance
Authors: Vijay Kumar
Venue: Communications of the ACM (1990)

Extendible hashing is a dynamic data structure which accommodates expansion and contraction of any stored data efficiently. In this article, an algorithm has been developed for managing concurrent operations on extendible hashing by achieving optimal memory utilization by supporting directly expansion and contraction, page split, and merge. The results of this study have been encouraging in the sense that it seems to provide a higher degree of concurrency compared to other algorithms on an extendible hash file.
Hypertext II
Authors: Jakob Nielsen
Venue: ACM SIGCHI Bulletin (1989)

Hypertext II was the major conference in Europe this year in the hypertext field and attracted 200 participants. Actually it had "attracted" many more who were just not there but had been turned away because the organizers had committed the same mistake as the planners of the Hypertext'87 conference in North Carolina and placed the conference in a location which would only hold 200 people. Their original assumption was that a hypertext conference in the UK might attract 100 participants, but that was the underestimate of the year. Hypertext is hot these days.
Local approximation study of difference operators by means of REDUCE system
Authors: V. G. Ganzha, M. Y. Shashkov
Venue: Proceedings of the international symposium on Symbolic and algebraic computation (1990)

This work is devoted to the description of new algorithms and programs in the REDUCE system for the automated study of a local order of the approximation of difference operator written on non-orthogonal meshes. The performance of the program is demonstrated by local approximation of several difference operators in one and two-dimensional cases.
Building block shaders
Authors: Gregory D. Abram, Turner Whitted
Venue: ACM SIGGRAPH Computer Graphics (1990)

This paper describes an implementation of Cook's "shade trees" in which shaders are described as networks of modules, building blocks, whose connections can be defined interactively.The high level interface to the shaders is a graphical editor which permits users to construct complex shaders by connecting shading elements in a network, in effect a graphical shading language. A low level interface to the shaders is also provided. In the low level interface, shading elements are programmed in a standard programming language and compiled into modules which can linked either at run time or compile time.Each link in the shading network represents a subroutine call. In essence, execution of the network is analogous to the execution of an interpreted language.
A very fast prototype retrieval system using statistical ranking
Authors: D. Harmon, G. Candela
Venue: ACM SIGIR Forum (1989)

The most striking result in working with Professor Gerald Salton over 20 years ago on the comparison between the SMART system and the MEDLARS system [Salton69] was the fact that whereas Boolean retrieval (MEDLARS) did very well or very poorly, the SMART system always seemed to find some of the relevant records. All of us working at Cornell University during that time wanted to run a full-scale comparison between these systems to demonstrate what was to us the clear superiority of a ranking retrieval system, but this was not possible due to lack of funding and other problems.
Block-iterative finite element computations for incompressible flow problems
Authors: T. E. Tezduyar, R. Glowinski, J. Liou, T. Nguyen, S. Poole
Venue: Proceedings of the 2nd international conference on Supercomputing (1988)

A block-iterative finite element procedure is presented for two-dimensional fluid dynamics computations on multiply-connected domains based on the vorticity - stream function formulation of the incompressible Navier-Stokes equations. The difficulty associated with the convection term in the vorticity transport equation is addressed by using a streamline-upwind/Petrov-Galerkin scheme. Element-by-element preconditioned iteration techniques with high degree of vectorization and high computational speed are employed to solve the linear equation system for each block. Performance evaluations show the potential of these techniques to be used for large-scale computations.
Decentralized mutual exclusion in the presence of link failures
Authors: C. S. Hsieh, R. A. Mata
Venue: Proceedings of the 17th conference on ACM Annual Computer Science Conference (1989)

A distributed algorithm for achieving mutual exclusion in a point-to-point network with lossy communication links is presented. A communication link is said to be lossy if it loses messages at will. The algorithm tolerates any number of lossy communication links, as long as the link failures do not partition the communication network. The message network is completely asynchronous and, hence, link failures are not detectable. In a network with n nodes and e links, the algorithm requires no more than 2e(2&radic;n + 1) message transmissions per mutual exclusion request.
RPC in the x-Kernel: evaluating new design techniques
Authors: L. Peterson, N. Hutchinson, S. O'Malley, M. Abbott
Venue: Proceedings of the twelfth ACM symposium on Operating systems principles (1989)

This paper reports our experiences implementing remote procedure call (RPC) protocols in the x-kernel. This exercise is interesting because the RPC protocols exploit two novel design techniques: virtual protocols and layered protocols. These techniques are made possible because the x-kernel provides an object-oriented infrastructure that supports three significant features: a uniform interface to all protocols, a late binding between protocol layers, and a small overhead for invoking any given protocol layer. For each design technique, the paper motivates the technique with a concrete example, describes how it is applied to the implementation of RPC protocols, and presents the results of experiments designed to evaluate the technique.
Expressing structural hypertext queries in graphlog
Authors: M. P. Consens, A. O. Mendelzon
Venue: Proceedings of the second annual ACM conference on Hypertext (1989)

GraphLog is a visual query language in which queries are formulated by drawing graph patterns. The hyperdocument graph is searched for all occurrences of these patterns. The language is powerful enough to allow the specification and manipulation of arbitrary subsets of the network and supports the computation of aggregate functions on subgraphs of the hyperdocument. It can support dynamically defined structures as well as inference capabilities, going beyond current static and passive hypertext systems. The expressive power of the language is a fundamental issue: too little power limits the applications of the language, while too much makes efficient implementation difficult and probably affects ease of use. The complexity and expressive power of GraphLog can be characterized precisely by using notions from deductive database theory and descriptive complexity. In this paper, from a practical point of view, we present examples of GraphLog queries applied to several different hypertext systems, providing evidence for the expressive power of the language, as well as for the convenience and naturalness of its graphical representation. We also describe an ongoing implementation of the language.
BPSES: a knowledge-based system for the design of nuclear power plant penetration seals
Authors: Enrique Tuason, William D. Cleaveland
Venue: Proceedings of the 2nd international conference on Industrial and engineering applications of artificial intelligence and expert systems - Volume 1 (1989)

This paper describes a knowledge-based system for the design of nuclear power plant penetration seals. The discussion includes the architecture of the penetration seal design system, and how the knowledge is represented. Additionally, it discusses the interfaces of the expert system kernel with external data base of CAD drawings of design details.
Travel around a learning support environment: rambling, orienteering or touring?
Authors: N. Hammond, L. Allinson
Venue: Proceedings of the SIGCHI conference on Human factors in computing systems (1988)

The traditionally separate application areas supported by database systems and instructional systems are merging in the area of learning support environments (LSEs). We discuss the provision of tools in LSEs for navigating around large knowledge bases. The optimal form of navigation will depend on the nature of the user and of the learning requirements, and thus a variety of tools must be provided. We propose the use of a travel holiday metaphor as a means for structuring a set of navigation tools and illustrate its use in a system for teaching non-formal fields of knowledge.
Avoiding Latch Formation in Regular Expression Recognizers
Authors: M. J. Foster
Venue: IEEE Transactions on Computers (1989)

Specialized silicon compilers, or module generators, are promising tools for automating the design of custom VLSI chips. In particular, generators for regular language recognizers have many applications. A problem called latch formation that causes regular expression recognizers to be more complex than they would first appear is identified. if recognizers are constructed in the most straightforward way from certain regular expressions, they may contain extraneous latches that cause incorrect operation. After identifying the problem, the article presents a source-to-source transformation that converts regular expressions that cause latch formation into expressions that do not. This transformation allows regular expression recognizers to be simpler, smaller, and faster, thus adding to the advantages of specialized silicon compilers.
Comparison of two-dimensional FFT methods on the hypercube
Authors: C. Y. Chu
Venue: Proceedings of the third conference on Hypercube concurrent computers and applications - Volume 2 (1989)

Complex two-dimensional FFTs up to size 256 x 256 points are implemented on the Intel iPSC/System 286 hypercube with emphasis on comparing the effects of data mapping, data transposition or communication needs, and the use of distributed FFTs. Two new implementations of the 2D-FFT include the Local-Distributed method which performs local FFTs in one direction followed by distributed FFTs in the other direction, and a Vector-Radix implementation that is derived from decimating the DFT in two-dimensions instead of one. In addition, the Transpose-Split method involving local FFTs in both directions with an intervening matrix transposition and the Block 2D-FFT involving distributed FFT butterflies in both directions are implemented and compared with the other two methods. Timing results show that on the Intel iPSC/System 286, there is hardly any difference between the methods, with the only differences arising from the efficiency or inefficiency of communication. Since the Intel cannot overlap communication and computation, this forces the user to buffer data. In some of the methods, this causes processor blocking during communication. Issues of vectorization, communication strategies, data storage and buffering requirements are investigated. A model is given that compares vectorization and communication complexity. While timing results show that the Transpose-Split method is in general slightly faster, our model shows that the Block method and Vector-Radix method have the potential to be faster if the communication difficulties were taken care of. Therefore if communication could be &ldquo;hidden&rdquo; within computation, the latter two methods can become useful with the Block method vectorizing the best and the Vector-Radix method having 25% fewer multiplications than row-column 2D-FFT methods. Finally the Local-Distributed method is a good hybrid method requiring no transposing and can be useful in certain circumstances. This paper provides some general guidelines in evaluating parallel distributed 2D-FFT implementations and concludes that while different methods may be best suited for different systems, better implementation techniques as well as faster algorithms still perform better when communication become more efficient.
A centralized methodology for multi-level abstraction in simulation
Authors: Steven Walczak, Paul Fishwick
Venue: ACM SIGSIM Simulation Digest (1988)

Simulation systems need to be able to serve the need of a large domain of users with varying requirements and expectations of a simulation system. The varying degree of requirements by a larger group of users will require the use of multiple abstraction levels within a simulation environment. A methodology for implementing simulation systems with multiple abstraction levels has been developed. This methodology permits the simulation system to have great flexibility in satisfying the requirements of a broad range of users.
The development of Prometheus: an expert system tool for preliminary design of spacecraft thermal control systems
Authors: Gary Barg, Nikola Djordjevic, Steven Hall
Venue: Proceedings of the 1st international conference on Industrial and engineering applications of artificial intelligence and expert systems - Volume 1 (1988)

Spacecraft thermal control system design is a complex application of thermal engineering. This design process has a structure that is common for many experienced thermal control system engineers. Prometheus, an expert system design tool, was developed to guide the thermal engineer to an acceptable preliminary design for a spacecraft thermal control system. Its architecture reflects the common structure of the thermal control system preliminary design process. The scope is intially limited to single payloads internal to the spacecraft and adjacent to the thermal sink. This scope will be expanded in the second year of development to include other thermal control system design options.
A performance evaluation of four parallel join algorithms in a shared-nothing multiprocessor environment
Authors: Donovan A. Schneider, David J. DeWitt
Venue: ACM SIGMOD Record (1989)

In this paper we analyze and compare four parallel join algorithms. Grace and Hybrid hash represent the class of hash-based join methods, Simple hash represents a looping algorithm with hashing, and our last algorithm is the more traditional sort-merge. The performance of each of the algorithms with different tuple distribution policies, the addition of bit vector filters, varying amounts of main-memory for joining, and non-uniformly distributed join attribute values is studied. The Hybrid hash-join algorithm is found to be superior except when the join attribute values of the inner relation are non-uniformly distributed and memory is limited. In this case, a more conservative algorithm such as the sort-merge algorithm should be used. The Gamma database machine serves as the host for the performance comparison.
A Transportable Programming Language (TPL) System. II. The Bifunctional Compiler System
Authors: Soklei Leong, S. Jodis, K. Sullivan, Oliver Jiang, P. A. D. de Maine
Venue: IEEE Transactions on Software Engineering (1990)

The transportable programming language (TPL) method is a high-level-language approach that uses a bifunctional compiler to efficiently convert code among various dialects of a particular high-level language (HLL) via the hypothetical parent of the high-level language (HPHLL). The TPL compiler system that has been implemented has three parts: a rule modifier, a table generator, and a TPL compiler. A metalanguage, called the conversion rule description language (CRDL), is used to describe the conversion of a dialect to HPHLL and of the HPHLL to another dialect. The table generator translates those descriptions to tabular forms that drive the bifunctional compiler. The TPL compiler can then be used to translate programs coded in a local dialect into HPHLL and vice versa. The rule modifier alters the descriptions of a default-a synthetic 'most common'-dialect. It greatly simplifies the task of writing the conversion descriptions for a new environment or dialect. The TPL method is now being extended so that it can be used to retarget a dialect of any HLL to a standard environment such as Ada. Details of the TPL compiler system are given.
The ergo attribute system
Authors: Robert L. Nord, Frank Pfenning
Venue: Proceedings of the third ACM SIGSOFT/SIGPLAN software engineering symposium on Practical software development environments (1989)

The Ergo Attribute System was designed to satisfy the requirements for attributes in a language-generic program derivation environment. It consists of three components: (1) an abstract data type of attributes that guarantees attribute consistency, (2) a Common Lisp implementation which combines demand-driven and incremental attribute evaluation in a novel way while allowing for attribute persistence over many generations of a program, and (3) an attribute-grammar compiler producing code based on this abstract data type from a high-level specification. Our experience with three major applications (one being the attribute-grammar compiler itself) confirms that the overhead in storing and accessing attributes incurred by our implementation scheme is more than offset by the gains from the demand-driven, incremental, and persistent nature of attribution.
A round trip to B-splines via de Casteljau
Authors: Hartmut Prautzsch
Venue: ACM Transactions on Graphics (TOG) (1989)

B-splines are constructed from B&eacute;zier curves solely using de Casteljau's construction. Divided differences are not being used, nor is Mansfield's recurrence formula presupposed. Yet, it is shown how to differentiate, subdivide, and evaluate a B-spline. These results are derived from the corresponding techniques of B&eacute;zier curves.
The 3DIS: an extensible object-oriented information management environment
Authors: Hamideh Afsarmanesh, Dennis McLeod
Venue: ACM Transactions on Information Systems (TOIS) (1989)

The 3-Dimensional Information Space (3DIS) is an extensible object-oriented framework for information management. It is specifically oriented toward supporting the database requirements for data-intensive information system applications in which (1) information objects of various levels of abstraction and modalities must be accommodated, (2) descriptive and structural information (metadata) is rich and dynamic, and (3) users who are not database experts must be able to design, manipulate, and evolve databases. In response to these needs, the 3DIS provides an approach in which data and the descriptive information about data are handled uniformly in an extensible framework. The 3DIS provides a simple, geometric, and formal representation of data which forms a basis for understanding, defining, and manipulating databases. Several prototype implementations based upon the 3DIS have been designed and implemented and are in experimental use.