ppxscal/embedding_network huggingface dataset:
Graphical methods for the design and analysis of simulation experiments
Authors: R. R. Barton, L. W. Schruben
Venue: Proceedings of the 21st conference on Winter simulation (1989)

In this paper we develop some intuitive graphical methods for designing, running, and analyzing simulation experiments. We first concentrate on the analysis of output plots from a single run; the concept of a standardized simulation output plot is presented and its use illustrated. The remainder of the paper involves the design of experiments that may involve several (sequential) simulation runs. Experimental design discussions in simulation often focus on special topics unique to the field. Control over random variables permits design techniques such as antithetic variates and common random number streams. Yet many of the general topics of experiment design including confounding, fractional designs, and sample size determination are important in a simulation setting. The second part of this tutorial will focus on these general topics and present some graphical tools for generating experiment designs: causal diagrams and multidimensional point plots.
Parallel processing support: so what is a :20Heisenbug&rdquo; anyway?
Authors: C. E. Pitts
Venue: Proceedings of the 17th annual ACM SIGUCCS conference on User Services (1989)

Parallel Processing is a technological innovation holding great promise for improving turnaround time for large scientific and engineering codes. The Cornell National Supercomputer Facility, CNSF, has been experimenting with parallel processing since 1986, in cooperation with the IBM Corporation. Initially, the experimentation involved staff. Later, limited numbers of researchers had access to the parallel processing software under the restrictive terms of various confidentiality agreements. But in 1988, our parallel processing situation underwent a drastic change with the general availability of IBM's Parallel FORTRAN. In May 1988 we made this software available to our general user community and began supporting these users through our normal support channels. The purpose of this paper is to share our experiences with supporting researchers in this new environment. I will offer an overview of the terminology necessary to discuss parallel processing, with apologies to the computer scientists who have developed this information. Since my information has been acquired &ldquo;hands on,&rdquo; rather than by reading the voluminous publications on parallel processing, I'm not going to attempt to provide scholarly references. I gratefully acknowledge the research and work done by many other members of the CNSF staff who contributed greatly to my learning process and the development of the CNSF educational materials which provide the basis for much of the technical information provided here. The bulk of the paper will focus on the CNSF experiences with supporting parallel processing, including coding and debugging strategies, promoting parallel processing to the scientific user community, and education efforts.
Theory formation in artificial intelligence
Authors: L.-M. Fu
Venue: Proceedings of the 17th conference on ACM Annual Computer Science Conference (1989)

Theories in terms of causal mechanisms and causal relationships are a critical component of problem solving in artificial intelligence. A theory for explaining a given observation should satisfy constraints based on causal knowledge. In this paper, we present a new approach to theory formation. Under this approach, a theory is formed by reasoning with causal constraints. The reasoning method is constraint-satisfaction. Each coherent set of causal mechanisms discovered by the method instantiates the domain causal model to generate a causal hypothesis. If the domain causal model is true, then it can be shown that one of the causal hypotheses generated is true. In the case of using multi-level constraints, a theory is refined into more details by reasoning top-down through the levels of constraints.
Precision Architecture
Authors: Ruby B. Lee
Venue: Computer (1989)

The processor component of the Hewlett-Packard Precision Architecture system is described. The architecture's goals, how the architecture addresses the spectrum of general-purpose user information processing needs, and some architectural design tradeoffs are examined. Extendibility and longevity features are considered.
Measured capacity of an Ethernet: myths and reality
Authors: D. R. Boggs, J. C. Mogul, C. A. Kent
Venue: Symposium proceedings on Communications architectures and protocols (1988)

Ethernet, a 10 Mbit/sec CSMA/CD network, is one of the most successful LAN technologies. Considerable confusion exists as to the actual capacity of an Ethernet, especially since some theoretical studies have examined operating regimes that are not characteristic of actual networks. Based on measurements of an actual implementation, we show that for a wide class of applications, Ethernet is capable of carrying its nominal bandwidth of useful traffic, and allocates the bandwidth fairly. We discuss how implementations can achieve this performance, describe some problems that have arisen in existing implementations, and suggest ways to avoid future problems.
Characterization of parallelism and deadlocks in distributed digital logic simulation
Authors: L. Soule, A. Gupta
Venue: Proceedings of the 26th ACM/IEEE Design Automation Conference (1989)

This paper explores the suitability of the Chandy-Misra algorithm for digital logic simulation. We use four realistic circuits as benchmarks for our analysis, with one of them being the vector-unit controller for the Titan supercomputer from Ardent. Our results show that the average number of logic elements available for concurrent execution ranges from 10 to 111 for the four circuits, with an overall average of 68. Although this is twice as much parallelism as that obtained by traditional event-driven algorithms for these circuits, we feel it is still too low. One major factor limiting concurrency is the large number of global synchronization points &mdash; &ldquo;deadlocks&rdquo; in the Chandy-Misra terminology &mdash; that occur during execution. Towards the goal of reducing the number of deadlocks, the paper presents a classification of the types of deadlocks that occur during digital logic simulation. Four different types are identified and described intuitively in terms of circuit structure. Using domain specific knowledge, the paper proposes methods for reducing these deadlock occurrences. For one of the benchmark circuits, the use of the proposed techniques eliminated all deadlocks and increased the average parallelism from 40 to 160. We believe that the use of such domain knowledge will make the Chandy-Misra algorithm significantly more effective than it would be in its generic form.
Utilization of B-trees with inserts, deletes and modifies
Authors: T. Johnson, D. Shasha
Venue: Proceedings of the eighth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems (1989)

The utilization of B-tree nodes determines the number of levels in the B-tree and hence its performance. Until now, the only analytical aid to the determination of a B-tree's utilization has been the analysis by Yao and related work. Yao showed that the utilization of B-tree nodes under pure inserts was 69%. We derive analytically and verify by simulation the utilization of B-tree nodes constructed from N inserts followed by M modifies (where M > N), where each modify is a delete followed by an insert. Assuming that nodes only merge when they are empty (the technique used in most database management systems), we show that the utilization is 39% as M becomes large. We extend this model to a parameterized mixture of inserts and modifies. Surprisingly, if the modifies are mixed with just 10% inserts, then the utilization is over 62%. We also calculated the probability of splitting and merging. We derive a simple rule-of-thumb that accurately calculates the probability of splitting. We present two models for computing this utilization, the more accurate of which remembers items inserted and then deleted in a node - we call such items ghosts.
Partition detection and optimistic commit for dynamically reconfigurable distributed databases
Authors: David Wong
Venue: Proceedings of the 1988 ACM SIGSMALL/PC symposium on ACTES (1988)

This paper addresses the problem of providing reliability in face of network partitioning for a dynamically reconfigurable distributed database system with an underlying hierarchical network topology. Solutions to the problems of partition detection and the proper termination of transactions are suggested. Passive partition detection protocols designed to handle node failures and connections are presented. The basis for these protocols is the idea of maintaining multiple network servers across the network to ensure communication within any cluster of two nodes. In the process, a network server allocation algorithm is derived to meet this need. This paper also proposes a new transaction management model based on the idea of non-blocking partition processing. An extended quorum-based commitment protocol and an optimistic quorum-based termination protocol are developed to support this goal.
Inference of k-Testable Languages in the Strict Sense and Application to Syntactic Pattern Recognition
Authors: P. García, E. Vidal
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1990)

The inductive inference of the class of k-testable languages in the strict sense (k-TSSL) is considered. A k-TSSL is essentially defined by a finite set of substrings of length k that are permitted to appear in the strings of the language. Given a positive sample R of strings of an unknown language, a deterministic finite-state automation that recognizes the smallest k-TSSL containing R is obtained. The inferred automation is shown to have a number of transitions bounded by O(m) where m is the number of substrings defining this k-TSSL, and the inference algorithm works in O(kn log m) where n is the sum of the lengths of all the strings in R. The proposed methods are illustrated through syntactic pattern recognition experiments in which a number of strings generated by ten given (source) non-k-TSSL grammars are used to infer ten k-TSSL stochastic automata, which are further used to classify new strings generated by the same source grammars. The results of these experiments are consistent with the theory and show the ability of (stochastic) k-TSSLs to approach other classes of regular languages.
Use of the EVTA process in the evaluation of human/system interaction and performance
Authors: M. T. Shaffer
Venue: ACM SIGCHI Bulletin (1989)

The EVTA process generates a task-descriptive data base (Dury et al., 1987, page 375) from a detailed analysis of operator's observable activities and communications. The essential features of the EVTA process are the use of video/audio equipment to gather permanent records of operator activities from operational environments, and the generation of an empirical record of activity times through a software package which builds, manages and analyzes the resulting data base.
Interactive scientific visualization and parallel display techniques
Authors: J. A. Sethian, J. B. Salem, A. F. Ghoniem
Venue: Proceedings of the 1988 ACM/IEEE conference on Supercomputing (1988)

In this paper, we describe a new graphics environment for essentially real-time interactive visualization of computational fluid mechanics. Within this environment, the researcher may interactively examine fluid data on a framebuffer with animated flow visualization diagnostics which mimic those in the experimental laboratory. This provides an effective and interactive way to analyze the underlying physical mechanisms, and to compare results with laboratory experiment. The system is implemented on a data parallel supercomputer attached to a framebuffer. Since most fluid visualization techniques are highly parallel in nature, this allows rapid animation of fluid motion. The fluid diagnostic tools include display of moving color contours for scalar fields, smoke/dye injection of passive particles to identify coherent flow structures, and bubble wire tracers for velocity profiles. We demonstrate our interactive graphics fluid flow system by analyzing data generated from a numerical simulation of laminar and turbulent flow over a backwards-facing step. Input parameters are menu-driven, and images are updated at nine frames updates per second.
Processing aggregate relational queries with hard time constraints
Authors: Wen-Chi Hou, Gultekin Ozsoyoglu, Baldeo K. Taneja
Venue: ACM SIGMOD Record (1989)

We consider those database environments in which queries have strict timing constraints, and develop a time-constrained query evaluation methodology. For aggregate relational algebra queries, we describe a time constrained query evaluation algorithm. The algorithm, which is implemented in our prototype DBMS, iteratively samples from input relations, and evaluates the associated estimators developed in our previous work, until a stopping criterion (e.g., a time quota or a desired error range) is satisfied. To determine sample sizes at each stage of the iteration (so that the time quota will not be overspent) we need to have (a) accurate sample selectivity estimations of the RA operators in the query, (b) precise time cost formulas, and (c) good time-control strategies. To estimate the sample selectivities of RA operators, we use a runtime sample selectivity estimation and improvement approach which is flexible. For query time estimations, we use time-cost formulas which are adaptive and precise. To use the time quota efficiently, we propose statistical and heuristic time-control strategies to control the risk of overspending the time quota. Preliminary evaluation of the implemented prototype is also presented.
A laboratory for teaching object oriented thinking
Authors: K. Beck, W. Cunningham
Venue: Conference proceedings on Object-oriented programming systems, languages and applications (1989)

It is difficult to introduce both novice and experienced procedural programmers to the anthropomorphic perspective necessary for object-oriented design. We introduce CRC cards, which characterize objects by class name, responsibilities, and collaborators, as a way of giving learners a direct experience of objects. We have found this approach successful in teaching novice programmers the concepts of objects, and in introducing experienced programmers to complicated existing designs.
A bridging model for parallel computation
Authors: Leslie G. Valiant
Venue: Communications of the ACM (1990)

The success of the von Neumann model of sequential computation is attributable to the fact that it is an efficient bridge between software and hardware: high-level languages can be efficiently compiled on to this model; yet it can be effeciently implemented in hardware. The author argues that an analogous bridge between software and hardware in required for parallel computation if that is to become as widely used. This article introduces the bulk-synchronous parallel (BSP) model as a candidate for this role, and gives results quantifying its efficiency both in implementing high-level language features and algorithms, as well as in being implemented in hardware.
The trouble with for-loop invariants
Authors: William J. Collins
Venue: ACM SIGCSE Bulletin (1988)

In this paper we discuss some of the problems in constructing and utilizing loop invariants for For-loops. Another kind of assertion, the loop post-invariant, is offered as an alternative to the loop invariant in designing, documenting and proving the correctness of For-loops.
Cautious Transaction Schedulers for Database Concurrency Control
Authors: Toshihide Ibaraki, Tiko Kameda, Naoki Katoh
Venue: IEEE Transactions on Software Engineering (1988)

Cautious schedulers, which never resort to rollbacks for the purpose of concurrency control, are investigated. In particular, cautious schedulers for classes WW consisting of schedules serializable under the write-write constraints, and WRW, a superclass of W, are considered. The cautious WW-scheduler has a number of nice properties, one of which is the existence of a polynomial-time scheduling algorithm. Since cautious WRW-scheduling is, in general, NP-complete, some restrictions are introduced which allow polynomial-time scheduling. All of these cautious schedulers are based on the assumption that transaction predeclare their read and write sets on arrival. Anomalies which occur when transaction modify their read sets or write sets during execution are discussed and countermeasures are proposed.
Multifunctional cursor for direct manipulation user interfaces
Authors: M. J. Muller
Venue: Proceedings of the SIGCHI conference on Human factors in computing systems (1988)

The multifunctional cursor (MC) is a technique for representing multiple operations in direct manipulation user interfaces. Icons for each of several simultaneously-available operations are overlaid into the cursor image. The MC improves user interface practice by removing syntactic inconsistencies, by reducing cognitive load, and by providing support for repeated operations.
KDA - A tool for automatic design evaluation and refinement using the blackboardmodel of control
Authors: H. Sharp
Venue: Proceedings of the 10th international conference on Software engineering (1988)

Interest in applying knowledge-based techniques in software engineering is growing, but little has yet been accomplished in the area of software design. This paper discusses the use of the blackboard model of control for design evaluation and refinement, and describes KDA (Knowledge-based Design Assistant) which has been built to demonstrate the applicability of this idea; the tool's architecture and example sessions are included and explained.
Simulation for decision making: an introduction
Authors: A. Thesen, L. E. Travis
Venue: Proceedings of the 21st conference on Winter simulation (1989)

We give an overview of simulation modeling and analysis from the perspective of prospective users wanting to use simulation as a decision aid. Important considerations in building simulation models and analyzing their outputs are discussed. A brief overview of available software is given. At the end of this tutorial, you should have a general understanding of simulation and an understanding of its applicability to your situation.
A comparison of adaptive refinement techniques for elliptic problems
Authors: William F. Mitchell
Venue: ACM Transactions on Mathematical Software (TOMS) (1989)

Adaptive refinement has proved to be a useful tool for reducing the size of the linear system of equations obtained by discretizing partial differential equations. We consider techniques for the adaptive refinement of triangulations used with the finite element method with piecewise linear functions. Several such techniques that differ mainly in the method for dividing triangles and the method for indicating which triangles have the largest error have been developed. We describe four methods for dividing triangles and eight methods for indicating errors. Angle bounds for the triangle division methods are compared. All combinations of triangle divisions and error indicators are compared in a numerical experiment using a population of eight test problems with a variety of difficulties (peaks, boundary layers, singularities, etc.). The comparison is based on the L-infinity norm of the error versus the number of vertices. It is found that all of the methods produce asymptotically optimal grids and that the number of vertices needed for a given error rarely differs by more than a factor of two.
The occasional distributivity of &deg; over +e and the change of variable formula for conjugate functions
Authors: S. Simons
Venue: Non-Linear Analysis (1990)

This is a test +e
Recovering Three-Dimensional Shape from a Single Image of Curved Objects
Authors: I. Malik, D. Maydan
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1989)

An algorithm to recover three-dimensional shape, i.e., surface orientation and relative depth from a single segmented image is presented. It is assumed that the scene is composed of opaque regular solid objects bounded by piecewise smooth surfaces with no markings or textures. It is also assumed that the reflectance map R(n) is known. For the canonical case of Lambertian surfaces illuminated by a point light source, this implies knowing the light-source direction. A variational formulation of line drawing and shading constraints in a common framework is developed. The global constraints are partitioned into constraint sets corresponding to the faces, edges and vertices in the scene. For a face, the constraints are given by Horn's image irradiance equation. A variational formulation of the constraints at an edge both from the known direction of the image curve corresponding to the edge and shading is developed. At a vertex, the constraints are modeled by a system of nonlinear equations. An algorithm is presented to solve this system of constraints.
Monitoring and performance measuring distributed systems during operation
Authors: D. Wybranietz, D. Haban
Venue: Proceedings of the 1988 ACM SIGMETRICS conference on Measurement and modeling of computer systems (1988)

This paper describes an integrated tool for monitoring distributed systems continuously during operation. A hybrid monitoring approach is used. As special hardware support a test and measurement processor (TMP) was designed, which is part of each node in an experimental multicomputer system. Each TMP runs local parts of the monitoring software for its node, while all the TMPs are connected to a central test station via a separate TMP interconnection network. The monitoring system is transparent to users. It permanently observes system behavior, measures system performance and records system information. The immense amount of information is graphically displayed in easy-to-read-charts and graphs in an application-oriented manner. The tools promote an improved understanding of run time behavior and performance measurements to derive qualitative and even quantitative assessments about distributed systems. A prototype of the monitoring facility is operational and currently experiments are being conducted in our distributed system consisting of several MC68000 microcomputers.
Matching Aerial Images to 3-D Terrain Maps
Authors: J. J. Rodriquez, J. K. Aggarwal
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1990)

A terrain-matching algorithm is presented for use in a passive aircraft navigation system. A sequence of aerial images is matched to a reference digital map of the 3-D terrain. Stereo analysis of successive images results in a recovered elevation map. A cliff map is then used as a novel compact representation of the 3-D surfaces. The position and heading of the aircraft are determined with a terrain-matching algorithm that locates the unknown cliff map within the reference cliff map. The robustness of the matching algorithm is demonstrated by experimental results using real terrain data.
Object-oriented programming: an objective sense of style
Authors: K. Lieberherr, I. Holland, A. Riel
Venue: ACM SIGPLAN Notices (1988)

We introduce a simple, programming language independent rule (known in-house as the Law of Demeter&trade;) which encodes the ideas of encapsulation and modularity in an easy to follow form for the object-oriented programmer. You tend to get the following related benefits when you follow the Law of Demeter while minimizing simultaneously code duplication, the number of method arguments and the number of methods per class: Easier software maintenance, less coupling between your methods, better information hiding, narrower interfaces, methods which are easier to reuse, and easier correctness proofs using structural induction. We discuss two important interpretations of the Law (strong and weak) and we prove that any object-oriented program can be transformed to satisfy the Law. We express the Law in several languages which support object-oriented programming, including Flavors, Smalltalk-80, CLOS, C++ and Eiffel.