ppxscal/embedding_network huggingface dataset:
Efficient consistency in deductive databases
Authors: G. Moerkotte, S. Karl
Venue: Lecture notes in computer science on ICDT '88 (1988)

In this paper a theoretical framework for efficiently checking the consistency of deductive databases is provided and proven to be correct. Our method is based on focussing on the relevant parts of the database by reasoning forwards from the updates of a transaction, and using this knowledge about real or just possible implicit updates for simplifying the consistency constraints in question. Opposite to the algorithms by Kowalski/Sadri and Lloyd/Topor, we are neither committed to determine the exact set of implicit updates nor to determine a fairly large superset of it by only considering the head literals of deductive rule clauses. Rather, our algorithm unifies these two approaches by allowing to choose any of the above or even intermediate strategies for any step of reasoning forwards. This flexibility renders possible the integration of statistical data and knowledge about access paths into the checking process. Second, deductive rules are organized into a graph to avoid searching for applicable rules in the proof procedure. This graph resembles a connection graph, however, a new method of interpreting it avoids the introduction of new clauses and links.
Recovery Point Selection on a Reverse Binary Tree Task Model
Authors: Shyh-Kwei Chen, W. T. Tsai, M. Bhavani Thuraisingham
Venue: IEEE Transactions on Software Engineering (1989)

An analysis is conducted of the complexity of placing recovery points where the computation is modeled as a reverse binary tree task model. The objective is to minimize the expected computation time of a program in the presence of faults. The method can be extended to an arbitrary reverse tree model. For uniprocessor systems, an optimal placement algorithm is proposed. For multiprocessor systems, a procedure for computing their performance is described. Since no closed form solution is available, an alternative measurement is proposed that has a closed form formula. On the basis of this formula, algorithms are devised for solving the recovery point placement problem. The estimated formula can be extended to include communication delays where the algorithm devised still applies.
Pessimal Guesses may be Optimal: A Counterintuitive Search Result
Authors: Kenneth R. Sloan, James Painter
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1988)

A particular style of search is considered that is motivated by the problem of reconstructing the surface of three-dimensional objects given a collection of planar contours representing cross-sections through the objects. An improvement on the simple divide-and-conquer method is presented. The key idea is to locate bottlenecks (minimal separators), which markedly reduces the number of searches required but reduces other measures (e.g. nodes expanded) by only a constant factor. It is observed that for well-behaved search spaces, the search efficiency can be improved further by making 'pessimal guesses'. This suggests a style of search in which the region of the search space thought to be close to the optimal solution (on whatever grounds are available) is examined last, while the outlying regions (the pessimal guesses) are examined first.
A new rapid prototyping firmware (RPF) tool
Authors: M. Andrews, F. Lam
Venue: Proceedings of the 21st annual workshop on Microprogramming and microarchitecture (1988)

Microprogramming has progressed from a method for systematically designing control units to its wide-spread application to the design, emulation, analysis, and implementation of instruction sets for general-purpose computers. The application was greatly enhanced through the family-oriented architectures of the IBM System 360 and on into the DEC PDP-11 family, culminating in the VAX family of machines. Today, systolic, VLSI, and VHSIC microarchitectures are demanding increased centralized microprogrammable control capability. However, microprogramming has always been a tedious, time consuming, difficult to verify and, therefore, costly exercise. A new rapid prototyping firmware (RPF) tool is described which ameliorates most of the problems.
Interactive graphics: a tool for beginning programming students in discovering solutions to novel problems
Authors: Helen Duerr Hays
Venue: ACM SIGCSE Bulletin (1988)

A computer-based, problem-solving exercise was developed, using dynamic graphics to assist beginning programming students in devising and testing solutions to novel problems (problems requiring solution methods with which the students were not already familiar). For evaluation, 103 beginning computer science students at Southeast Missouri State University, were each randomly assigned one of three forms of the exercise containing four array-manipulation problems. The control group worked all four problems without the aid of dynamic graphics; whereas, on Problems 3 and 4, the first experimental group was allowed to test possible solutions by observing graphical execution of attempted code, and the second experimental group was allowed to interactively manipulate the elements of the array by means of arrow keys in order to devise a solution, in addition to observing the graphical execution of their code. Six measures of improvement in performance on Problem 4 over Problem 2 were made for each subject. The one-tailed Wilcoxon two-sample test was applied, using significance level .05, to compare mean scores between groups. The second experimental group showed significantly more improvement than the control group as measured by four of the six scores, and the first experimental group showed significantly more improvement than the control group as measured by two of the six scores. Although the second experimental group scored slightly higher than the first on all but one measure, no significant difference was observable between the two experimental groups. On a follow-up quiz, each experimental group scored slightly, but not significantly, higher than the control group. Additionally, it was noted that only students who had made a score of 13 or more on the KSW Computer Science Placement Exam were able to work either of the two problems used for evaluation.
On the improbability of reaching Byzantine agreements
Authors: R. L. Graham, A. C. Yao
Venue: Proceedings of the twenty-first annual ACM symposium on Theory of computing (1989)

It is well known that for the Byzantine Generals Problem, no deterministic protocol can exist for an n-processor system if the number t of faulty processors is allowed to be as large as n/3. In this paper we investigate the maximum achievable agreement probability &Bgr;n,t in a model in which the faulty processors can be as devious and powerful as possible. We also discuss a restricted model with &Bgr;n,t denoting the corresponding maximum achievable probability. We will prove that: (i) for n = 3, t = 1 (the first nontrivial case), &Bgr;3,1 = (&radic;5 - 1)/2 (the reciprocal of the golden ratio); (ii) for all &egr; with 0 < &egr; < 1, if t/n > 1 - log (1 -&egr;)1/2/ log (1 - (1 -&egr;)1/2) then &Bgr;tn,t < &egr;
Viewing object as patterns of communicating agents
Authors: Oscar Nierstrasz, Michael Papathomas
Venue: ACM SIGPLAN Notices (1990)

Following our own experience developing a concurrent object-oriented language as well of that of other researchers, we have identified several key problems in the design of a concurrency model compatible with the mechanisms of object-oriented programming. We propose an approach to language design in which an executable notation describing the behaviour of communicating agents is extended by syntactic patterns that encapsulate language constructs. We indicate how various language models can be accommodated, and how mechanisms such as inheritance can be modeled. Finally, we introduce a new notion of types that characterizes concurrent objects in terms of their externally visible behaviour.
Efficient high-level iteration with accumulators
Authors: Robert D. Cameron
Venue: ACM Transactions on Programming Languages and Systems (TOPLAS) (1989)

Accumulators are proposed as a new type of high-level iteration construct for imperative languages. Accumulators are user-programmed mechanisms for successively combining a sequence of values into a single result value. The accumulated result can either be a simple numeric value such as the sum of a series or a data structure such as a list. Accumulators naturally complement constructs that allow iteration through user-programmed sequences of values such as the iterators of CLU and the generators of Alphard. A practical design for high-level iteration is illustrated by way of an extension to Modula-2 called Modula Plus. The extension incorporates both a redesigned mechanism for iterators as well as the accumulator design. Several applications are illustrated including both numeric and data structure accumulation. It is shown that the design supports efficient iteration both because it is amenable to implementation via in-line coding and because it allows high-level iteration concepts to be implemented as encapsulations of efficient low-level manipulations.
Model-based knowledge acquisition for heuristic classification systems
Authors: E. Plaza, R. L. de Màntaras
Venue: Issue 108 (April 1989) (1989)

We present a methodology and an implemented system, EAR*, for supporting knowledge acquisition. Its goal is to build an implementation-independent knowledge-level description of the target knowledge base, guided by our current understanding of the generic structure of heuristic classification systems.
A VLSI Design for Computing Exponentiations in GF(2/sup m/) and its Application to Generate Pseudorandom Number Sequences
Authors: Charles C. Wang, Dingyi Pei
Venue: IEEE Transactions on Computers (1990)

A VLSI design for computing exponentiation in finite fields is developed. An algorithm to generate a relatively long pseudorandom number sequence is presented. It is shown that the period of this sequence is significantly increased compared to that of the sequence generated by the most commonly used maximal length shift register scheme.
Algorithm 682: Talbot's method of the Laplace inversion problems
Authors: A. Murli, M. Rizzardi
Venue: ACM Transactions on Mathematical Software (TOMS) (1990)

We describe a FORTRAN implementation, and some related problems, of Talbot's method which numerically solves the inversion problem of almost arbitrary Laplace transforms by means of special contour integration. The basic idea is to take into account computer precision to derive a special contour where integration will be carried out.
A general purpose animator
Authors: D. T. Brunner, J. O. Henriksen
Venue: Proceedings of the 21st conference on Winter simulation (1989)

During the 1980s, the simulation discipline has been revolutionized by the introduction of software for graphical, animated depiction of a running simulation on a display screen. Advocates of simulation animation have given several main reasons for using animation.There have also been some detractors who felt that animation was not always an appropriate tool. However, it has become clear that animation is here to stay. Discussion is shifting to comparisons among various animation tools and mapping out future directions for animation.Wolverine Software Corporation waited several years before beginning development of animation software. The company began animation development work in 1987, with the benefit of having observed and otherwise learned about the strengths and weaknesses of then-existing software.The preliminary results of the development effort are now available in product form. Wolverine has developed a general purpose animator. This software has a wide variety of applications and, thanks to its open architecture, can be used in conjunction with virtually any simulation software and in some non-simulation areas as well. For the IBM PC platform on which it runs, the product redefines several performance characteristics, most notably with its smooth motion and its geometry-based internal data structure.
Examining compiled code
Authors: M. Smotherman
Venue: ACM SIGCSE Bulletin (1989)

The use of annotated listings of compiler-generated code has the potential to make teaching more effective in several different courses. We consider the production of such listings for several popular compilers and computer systems, including Turbo Pascal on MS-DOS machines and Pascal on Ultrix and VMS systems. The usefulness of these listings in assembly language, computer organization/architecture, and compiler courses, as well as introductory courses, is also considered.
The alternating fixpoint of logic programs with negation
Authors: A. Van Gelder
Venue: Proceedings of the eighth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems (1989)

We introduce and describe the alternating fixpoint of a logic program with negation. The underlying idea is to monotonically build up a set of negative conclusions until the least fixpoint is reached, using a transformation related to the one that defines stable models, developed by Gelfand and Lifschitz. From a fixed set of negative conclusions, we can derive the positive conclusions that follow (without deriving any further negative ones), by traditional Horn clause semantics. The union of positive and negative conclusions is called the alternating fixpoint partial model. The name &ldquo;alternating&rdquo; was chosen because the transformation runs in two passes; the first pass transforms an underestimate of the set of negative conclusions into an (intermediate) overestimate; the second pass transforms the overestimates into a new underestimate; the composition of the two passes is monotonic. Our main theorem is that the alternating fixpoint partial model is exactly the well-founded partial model. We also show that a system is fixpoint logic, which permits rule bodies to be first order formulas but requires inductive relations to be positive within them, can be transformed straightforwardly into a normal logic program whose alternating fixpoint partial model corresponds to the least fixpoint of the fixpoint logic system. Thus alternating fixpoint logic is at least as expressive as fixpoint logic. The converse is shown to hold for finite structures.
A compositional approach to superimposition
Authors: L. Bougé, N. Francez
Venue: Proceedings of the 15th ACM SIGPLAN-SIGACT symposium on Principles of programming languages (1988)

A general definition of the notion of superimposition is presented. We show that previous constructions under the same name can be seen as special cases of our definition. We consider several properties of superimposition definable in our terms, notably the nonfreezing property. We also consider a syntactic representation of our construct in CSP
Snoopy cache test-and-test-and-set without execessive bus contention
Authors: Andy Glew, Wen-Mei Hwu
Venue: ACM SIGARCH Computer Architecture News (1990)

This paper analyzes the burst of bus traffic that occurs when a lock is released that is being waited for in a test-and-test-and-set spinloop. It is typically O (N) and can be O (N2), depending on assumptions about system behaviour, where N is the number of processors. Supporting a single feature in the bus interface, abandoning pending lock requests, reduces this to O (1). Such a feature is already possible on some systems and busses, but has not been applied to synchronization.
Directory-Based Cache Coherence in Large-Scale Multiprocessors
Authors: David Chaiken, Craig Fields, Kiyoshi Kurihara, Anant Agarwal
Venue: Computer (1990)

The usefulness of shared-data caches in large-scale multiprocessors, the relative merits of different coherence schemes, and system-level methods for improving directory efficiency are addressed. The research presented is part of an effort to build a high-performance, large-scale multiprocessor. The various classes of cache directory schemes are described, and a method of measuring cache coherence is presented. The various directory schemes are analyzed, and ways of improving the performance of directories are considered. It is found that the best solutions to the cache-coherence problem result from a synergy between a multiprocessor's software and hardware components.
Conscientious programming using PMA
Authors: Guy Barker, Douglas J. Keenan, Herman van Loon
Venue: ACM SIGAPL APL Quote Quad (1990)

This paper describes the use of APL systems at Philips to assist in providing a controlled application support environment and examines in detail an APL software management system, PMA (Program Maintenance Aid).
Sirpent: a high-performance internetworking approach
Authors: D. R. Cheriton
Venue: ACM SIGCOMM Computer Communication Review (1989)

A clear target for computer communication technology is to support a high-performance global internetwork. Current internetworking approaches use either concatenated virtual circuits, as in X.75, or a &ldquo;universal&rdquo; internetwork datagram, as in the DoD Internet IP protocol and the ISO connectionless network protocol (CLNP). Both approaches have significant disadvantages. This paper describes Sirpent&trade; (Source Internetwork Routing Protocol with Extended Network Transfer)1, a new approach to an internetwork architecture that makes source routing the basis for interconnection, rather than an option as in IP. Its benefits include simple switching with low per-packet processing and delay, support for accounting and congestion control, and scalability to a global internetwork. It also supports flexible, user-controlled routing such as required for security, policy-based routing and realtime applications. We also propose a specific internetwork protocol, called VIPER&trade;2, as a realization of the Sirpent approach.
Some measures and procedures for evaluation of the user interface in an information retrieval system
Authors: J. Tague, R. Schultz
Venue: Proceedings of the 11th annual international ACM SIGIR conference on Research and development in information retrieval (1988)

Planning the evaluation of an information retrieval system involves two steps: first, a determination of performance descriptors and measures appropriate to the system objectives and, secondly, a development of an evaluation design which ensures the effect of variation in components of interest will be isolated and assessed in an unbiased fashion. This paper examines the question of retrieval system evaluation from the perspective of the user. It presents evaluation procedures which are appropriate to this perspective and which can be used to isolate the effect of variation in the user interface to the system. The general procedure is exemplified by an application to evaluation of an experimental OPAC interface.
An overview of the Kyushu University reconfigurable parallel processor
Authors: Kazuaki Murakami, Akira Fukuda, Toshinori Sueyoshi, Shinji Tomita
Venue: ACM SIGARCH Computer Architecture News (1988)

As a testbed to investigate systemwide aspects of highly parallel processing, a reconfigurable parallel processor system is currently developed at the Kyushu University in Japan. The system is a MIMD- type multiprocessor which consists of N processing-elements (currently N is 128) fully connected by S N times;N crossbar networks (currently S is 1). Each processing-element (PE) employs a Fujitsu SPARC MB86900/10 chip-set, a Weitek WTL1164/65 chip-set and 4 Mbytes of memory. Although memory are organized to be distributed among all PEs, the system can be reconfigured as either a memory-shared tightly coupled multiprocessor or a message-passing loosely coupled multiprocessor at run time; also as a hybrid of the two. The crossbar network allows users to take arbitrary topologies for inter-PE (i.e. processor-memory and/or processor-processor) paths under software control of an operating system. The parallel/distributed operating system is also under development to exploit parallelism by making the best of reconfigurability. The full 128-PE configuration will provide up to 1.28 GIPS, 205 MFLOPS (single precision LINPACK), 141 MFLOPS (double precision LINPACK), 512 Mbytes of memory and 1.28 Gbytes/s inter-PE communication. This paper outlines the reconfigurable network and memory architectures among several unique architectural features of the reconfigurable parallel processor.
Why the look and feel of software user interfaces should not be protected by copyright law
Authors: P. Samuelson
Venue: Communications of the ACM (1989)

An attorney looks at how copyright law is applied to the protection of software user interfaces and makes a strong case for reevaluating the way the law views software.
Issues in data base management for APL2
Authors: R. D. Stockbridge, A. Eisner, R. Jernigan
Venue: ACM SIGAPL APL Quote Quad (1987)

APL2 is an excellent user interface to the dynamic facilities of IBM's DB2, a relational data base management system for the MVS operating system. An APL2/DB2 application has been written that utilizes the Generalized Command Syntax (GCS) of Jernigan for data base block processing. Our experience has led to the identification of several issues whose resolution affects the performance of our application. One issue concerns the use of large nested arrays in APL2. Another addresses the design of an efficient and effective data base update procedure that employs the current AP (auxiliary processor) 127, which is the interface between APL2 and DB2. These issues are formulated and discussed. The potential benefit of modifying AP 127 is suggested.
Training software (TS) case study: feature selection system (FSS) for computer personnel
Authors: A. Rushinek, S. Rushinek
Venue: ACM SIGCPR Computer Personnel (1989)

The selection of appropriate features for inclusion in microcomputer systems can be very frustrating for both hardware and software manufacturers, as well as for end-users. This study describes an interactive microcomputer based Feature Selection System (FSS). The Feature Price Contribution Margin (FPCM) measures to what degree a specific feature meets end-user needs. FSS produces a segmented income statement of possible future products lines. It also compares the outcome of integrating and bundling a feature into a product versus marketing this feature as a separate "add-on" product line.
Password cracking: a game of wits
Authors: Donn Seeley
Venue: Communications of the ACM (1989)

The following report has been gleaned from "A Tour of the Worm," an in-depth account of the November Internet infection. The author found the worm's crypt algorithm a frustrating, yet engaging, puzzle.
Quick-fix consulting: a user disservice
Authors: M. L. Mason
Venue: Proceedings of the 17th annual ACM SIGUCCS conference on User Services (1989)

In the face of expanding technology and demands for service accompanied by less-rapidly expanding budgets, consultants in the user services sections of university computing centers must be creative in their approach to distributing their consulting expertise. Quick-fix consulting is a user disservice. It must be replaced by consulting which begins with identifying and serving the individual user's immediate need and is followed by user education along with planning and preparation for the future.
A Unified Approach to the Change of Resolution: Space and Gray-Level
Authors: S. Peleg, M. Werman, H. Rom
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1989)

It is shown that by defining a suitable measure for the comparison of images, changes in resolution can be treated with the same tool as changes in color resolution. A gray-tone image, for example, can be compared to a half-tone image having only two colors (black and white), but of higher spatial resolution. A graph-theoretical definition of the basic measure used is introduced. This is followed by application to spatial resampling and gray-level requantization. This results in a hybrid treatment of resolution, and the possibility of trading spatial for gray-level resolution and vice versa.