ppxscal/embedding_network huggingface dataset:
A model to evaluate the effects of the BWB mechanism in a DQDB network in underload conditions
Authors: M. Conti, E. Gregori, L. Lenzini
Venue: Proceedings of the 1992 ACM annual conference on Communications (1992)

This paper analyzes how the BWB mechanism influences the status of slots traveling on the bus (slot-occupancy-pattern process) in a DQDB network. To capture the most important dependencies between consecutive slots at light-moderate load [CONTI91c] we have modeled the slot-occupancy-pattern process via a discrete-time first-order Markov process. In this paper we use a simplified DQDB network [CONTI91b] for which we derive a closed formula for the joint probability density function for the slot-occupancy-pattern of two consecutive slots. Our formulas are used to show the relationship between load, network configuration, BWB value and the slot-occupancy-pattern process.
On the potential of asynchronous pipelined processors
Authors: Ran Ginosar, Nick Michell
Venue: ACM SIGARCH Computer Architecture News (1990)

An asynchronous version of the pipelined R3000 and DLX processors, the A3000, is being designed. Simulation was employed to investigate the potential speed-up obtainable due to the asynchronous operation. Preliminary results show up to a 64% improvement in performance.
Teamwork Support in a Knowledge-Based Information Systems Environment
Authors: Udo Hahn, Matthias Jarke, Thomas Rose
Venue: IEEE Transactions on Software Engineering (1991)

Development assistance for interactive database applications (DAIDA) is an experimental environment for the knowledge-assisted development and maintenance of database-intensive information systems from object-oriented requirements and specifications. Within the DAIDA framework, an approach to integrate different tasks encountered in software projects via a conceptual modeling strategy has been developed. Emphasis is put on integrating the semantics of the software development domain with aspects of group work, on social strategies to negotiate problems by argumentation, and on assigning responsibilities for task fulfillment by way of contracting. The implementation of a prototype is demonstrated with a sample session.
Computing Curricula 1991
Authors: Allen B. Tucker
Venue: Communications of the ACM (1991)

ACM first published recommendations for undergraduate programs in computer science in 1968 in a report called &ldquo;Curriculum '68.&rdquo; The report was produced as an activity of the ACM Education Board, which since then has been providing updates to recommendations for computer science programs as well as recommendations for other academic programs in computing.
OPAC (abstract): A floating-point coprocessor dedicated to compute-bound kernels
Authors: André Seznec, Karl Courtel
Venue: ACM SIGARCH Computer Architecture News (1992)

In many applications, the main part of the computations may be encapsulated in compute-bounds kernels. Achieving high performance on compute-bound primitives at a low hardware cost has become an important challenge. OPAC was designed as the basic cell of a floating-point coprocessor dedicated to the execution of compute-bound kernels. Due to efficient hardware mechanisms for controlling and sequencing a pipeline performance close to a floating-point multiply-add percycle per cell is reached on applications such as solving linear systems, FFTs correlations in a microprocessor environment.
A Note on t-Unidirectional Error Correcting and d(d=t)-Unidirectional Error Detecting (t-UEC and d-UED) Codes
Authors: Kohichi Sakaniwa, Tae Nam Ahn, T. R. N. Rao
Venue: IEEE Transactions on Computers (1991)

Necessary and sufficient conditions for t-unidirectional error correcting and d-unidirectional error detecting (t-UEC and d-UED) codes are shown. In addition, an error in a theorem previously published on t-UEC and d-UED codes is corrected.
An integrated data structure with multiple access paths for database systems
Authors: Judy Mullins, Vijay Kumar
Venue: Proceedings of the 1992 ACM annual conference on Communications (1992)

This article presents an integrated data structure which offers multiple access paths for processing different types of queries efficiently. The data structure is developed by fusing the B+ - tree, the grid file and extendible hashing structures using a proper interface. We show that this type of data structure is an efficient way for providing multiple access paths to data.
An Algorithm for Redundant Binary Bit-Pipelined Rational Arithmetic
Authors: P. Kornerup, D. W. Matula
Venue: IEEE Transactions on Computers (1990)

The authors introduce a redundant binary representation of the rationals and an associated algorithm for computing the sum, difference, product, quotient, and other useful functions of two rational operands, using this representation. The algorithm extends R.W. Gosper's (1972) partial quotient arithmetic algorithm and allows the design of an online arithmetic unit with computations granularized at the signed bit level. Each input or output port can be independently set to receive/produce operands/result in either binary radix or the binary rational representation. The authors investigate by simulation the interconnection of several such units for the parallel computation of more complicated expressions in a tree-pipelined manner, with particular regard to measuring individual and compounded online delays.
Database theory column
Authors: Serge Abiteboul, Paris Kanellakis
Venue: ACM SIGACT News (1990)

Complex object databases have been proposed as a significant extension of relational databases, with many practical applications. In the second database theory column, we present languages for the manipulation of such databases: a many-sorted algebra and an equivalent calculus. Without attempting to standardize, we try to provide general and short definitions that highlight the two key constructors of complex objects: tuples and (finite) sets. We comment on issues, such as language expressive power and complexity, and we describe equivalent rule-based languages with fixpoint semantics. Finally, we review the state-of-the art in database complex objects and list some interesting open questions.
Load balancing requires &OHgr;(log*n) expected time
Authors: Philip D. MacKenzie
Venue: Proceedings of the third annual ACM-SIAM symposium on Discrete algorithms (1992)

In order to obtain very fast parallel algorithms, it is almost always necessary to have some sort of load balancing procedure, so that processors which have finished their required tasks can help processors which have not. If the overloaded processors are not helped, then the expected time of the entire algorithm suffers. In general, we would like to distribute the remaining work as evenly as possible among the processors, or more formally, given at most n independent tasks distributed in an arbitrary way among n processors, we would like to redistribute the tasks so that each processor contains O(1) tasks. We show here that even on the strongest randomized CRCW PRAM model, for a simple random distribution tasks load balancing requires &OHgr;(log* n) expected time. Gil, Matias, and Vishkin [9] give an O(log* n) expected time randomized algorithm which solves the load balancing problem in the worst case, so the lower bound is tight. By reduction we show that both Padded Sort [12], and Linear Approximate Compaction [13] require &OHgr;(log* n) expected time. We note that our basic technique is one of the few parallel lower bound techniques known which only require 0/1 inputs. We also note that the bounds given in this paper do not place any restriction on the instruction set of the machine, the amount of information which can be stored in a memory cell, or on the number of memory cells.
Interactive computers in anatomical instruction: the Vesalius project
Authors: Thomas O. McCracken, Thomas L. Spurgeon
Venue: ACM SIGBIO Newsletter (1992)

The goal of the Vesalius Project is a high-resolution, interactive 3-D atlas of human/animal anatomy, stored on a laser videodisc and displayed on graphics workstations---an "electronic Gray's Anatomy." Students will use this computerized atlas interactively to learn the structure of the body and to understand their own bodies in health and disease. The Human Factors Research Laboratory at Colorado State University has designed and is conducting a comprehensive evaluation program for the project.
Improved Diagnosability Algorithms
Authors: Vijay Raghavan, Anand R. Tripathi
Venue: IEEE Transactions on Computers (1991)

The concepts of the PMC and BGM self-diagnosing system models of F. P. Preparata et al. (1967) and F. Barsi et al. (1976), respectively, including the notions of fault sets, consistency, and diagnosability number, are reviewed. Two one-step diagnosability algorithms are applied, one to the PMC model and the other to the BGM model. In both models, one-step diagnosability refers to a system's ability to determine all the faulty units from single collection of test results. Using the letters n, m, and tau to denote the number of units, the number of tests, and the diagnosability number, respectively, it is shown that in the BGM model the algorithm has a complexity of O(n tau /sup 2//log tau ), and, in the PMC model, the algorithm has a complexity of O(n tau /sup 2.5/).
Legally speaking: is information property?
Authors: Pamela Samuelson
Venue: Communications of the ACM (1991)

This column will discuss why the law has traditionally resisted characterizing information as the sort of thing that can be private property, and will speculate about why judges may be more receptive nowadays to assertions that information should be treated as property. This new attitude is illustrated by a 1987 U.S. Supreme Court decision which upheld criminal convictions based solely on the misappropriation of information which the Court found to be the property of one of the defendants' employers.
Two models for integrating persistence and lazy functional languages
Authors: David J. McNally, Antony J. T. Davie
Venue: ACM SIGPLAN Notices (1991)

A new programming system --- STAPLE (Statically Typed Applicative Persistent Language Environment) --- which integrates a lazy functional programming language and a persistent store is described. The motivation for introducing orthogonal persistence into a functional setting is given. Two models for achieving this integration are then described together with a discussion of the way laziness interacts with persistence and the benefits resulting from this interaction. In the first model, a system of persistent modules allows the programmer to create persistent values by naming them in a module. In the second model, a combination of stream I/O and a dynamic type allows functional programs to manipulate values already in the persistent store and to allow dynamically created values to become persistent.
Introducing functional programming in discrete mathematics
Authors: Roger L. Wainwright
Venue: Proceedings of the twenty-third SIGCSE technical symposium on Computer science education (1992)

Programming assignments in my discrete mathematics course have changed recently due to an influx of non-computer science students with little or no programming experience. Programming problems are now assigned in a simple to learn, easy to write, mathematical-like functional programming language that requires no previous programming experience. In theory, all students begin on the same basis. Exposure to the concepts of functional programming is an essential part of computer science and mathematics curricula. For most students this is the only exposure to functional programming. Functional programming and discrete mathematics are a natural combination. One week of lectures and perhaps a small monetary investment is all that is required. An instructor totally unfamiliar with functional programming can easily learn enough in a week or so to present a simple introduction to the topic. Introducing functional programming concepts in discrete mathematics was very successful. Students found the exposure to functional programming to be an insight they had never experienced before and enthusiastically recommended an introduction to functional programming be a permanent part of the course.
Logical Time in Distributed Computing Systems
Authors: Colin Fidge
Venue: Computer (1991)

The partial ordering of events as defined by their causal relationships, that is, the ability of one event to directly, or transitively, affect another is defined. Its generalized and practical implementations in terms of partially ordered logical clocks are described. Such clocks can provide a decentralized definition of time for distributed computing systems, which lack a common time base. In their full generality, partially ordered logical clocks may be impractically expensive for long-lived computations. Several possible optimizations, depending on the application environment in which the clocks will be used, are described. Some applications are summarized.
The human element
Authors: Peter G. Neumann
Venue: Communications of the ACM (1991)

In past issues we have discussed various system-related disasters and their causes, both accidental and intentional. In almost all cases it is possible to allocate to people&mdash;directly or indirectly&mdash;those difficulties allegedly attributed to &ldquo;computer problems.&rdquo; But too much effort seems directed at placing blame and identifying scapegoats, and not enough on learning from experiences and avoiding such problems [1,2,5,6,7]. Besides, the real causes may implicitly or explicitly involve a multiplicity of developers, customers, users, operators, administrators, others involve with computer and communication systems, and sometimes even unsuspecting bystanders. In a few cases the physical environment also contributes, e.g., power outages, floods, extreme weather, lightning, and earthquakes. Even in those cases there may have been system people who failed to anticipate the possible effects. In principle, at least, we can design redundantly distributed systems that are able to withstand certain hardware faults, component unavailabilities, extreme delays, human errors, malicious misuse, and even &ldquo;acts of God&rdquo;&mdash;at least within limits. Nevertheless, in surprisingly many systems (including systems designed to provide continuous availability), an entire system can be brought to a screeching halt by a simple event just as by a complex one [4].
An Integrated Approach to 3D Motion Analysis and Object Recognition
Authors: Mun K. Leung, Thomas S. Huang
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1991)

An integrated system for 3D motion estimation and object recognition with outdoor stereo image sequences as inputs is presented. The goals are to obtain from input stereo images the 3D motion description and the identification of a vehicle moving against a stationary background. In order to accomplish the desired goals, the system consists of four stages; motion estimation, distinctive feature extraction, model database, and object recognition. The results of 3D motion estimation are used to narrow down considerably the search space in the stage of object recognition. The system is applied to eight sets of stereo image pairs. Experimental results demonstrate that the system can successfully provide the 3D motion description and the identification of the vehicle in all the stereo image pairs.
Asynchronous transfer of control in Ada 9X
Authors: A. Burns, A. J. Wellings, G. L. Davies
Venue: ACM SIGAda Ada Letters (1990)

The Taft proposal is described in detail. It involves introducing a new "and" clause into the select statement thereby providing a means of programming asynchronous transfer of control without the use of the abort facility. An evaluation of the proposal considers some of its limitations, the major one of which is the possibility of deadlock if a group of tasks use the facility to affect each other. Ways of removing this difficulty are considered. The model is then compared with the alternative of introducing asynchronous exceptions. Finally a unified model is presented that combines the advantages of the Taft proposal and asynchronous exceptions.
Nonlinear Image Filtering with Edge and Corner Enhancement
Authors: Mark Nitzberg, Takahiro Shiota
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1992)

The authors describe a model of nonlinear image filtering for noise reduction and edge enhancement using anisotropic diffusion. The method is designed to enhance not only edges, but corners and T junctions as well. The method roughly corresponds to a nonlinear diffusion process with backward heat flow across the strong edges. Such a process is ill posed, making the results depend strongly on how the algorithm differs from the diffusion process. Two ways of modifying the equations using simulations on a variable grid are studied.
In support of the Ada 9X real-time facilities
Authors: A. Burns, A. J. Wellings
Venue: ACM SIGAda Ada Letters (1992)

The Ada9x mapping has been criticised as being over ambitious and at odds with the &ldquo;minimum change maximum benefit&rdquo; AJPO dictum. Consequently there is a need to cut back the scope of the proposed changes. This report considers the proposed changes which affect the programming of real-time single processor and multiprocessor systems. We argue that protected records, select waiting, asynchronous transfer of control, nested asynchronous transfer of control are all essential core facilities, and if any of these are omitted the success of Ada 9x in addressing the needs of the real-time community would be in serious jeopardy. If language simplification are deemed necessary, we would advocate the removal of user-defined timers, finalisation (but not abort exit handlers), and protected record functions.
The Imposition of Protocols Over Open Distributed Systems
Authors: Naftaly H. Minsky
Venue: IEEE Transactions on Software Engineering (1991)

In order to facilitate enforcement of protocols, an architecture for distributed systems is introduced under which all interactions between objects are governed by an explicit and strictly enforced set of rules, called the law of the system. This law is global in the sense that all the objects of the system are made to obey it, but the maintenance of the law and its enforcement are performed locally, at each object (or node). The term law is used to emphasized that it not only provides the specification of protocols, but actually governs the system by enforcing them. In other words, under this architecture a protocol can be established simply by writing it into the law of a system, without having to worry about the programs that drive the various objects that might populate that system. The law, then, is the enforced specification of protocols. It is shown that various familiar protocols can be established under this architecture. A technique for online distributed updating of the global law of a system is presented.
The HCI Bibliography project
Authors: Gary Perlman
Venue: ACM SIGCHI Bulletin (1991)

The HCI Bibliography project has just released its first collections of a free-access online extended bibliography on Human-Computer Interaction. The basic goal of the project is to put an online bibliography for most of HCI on the screens of all researchers and developers in the field through anonymous ftp access, mail servers, and Mac and DOS floppy disks. Through the efforts of volunteers, the bibliography is approaching 1000 entries, with abstracts and/or tables of contents; eventually, citation information and hypertext access will be added. The first release contains the complete contents of all the ACM CHI conference, the complete journal Human-Computer Interaction, and several other important sources. Eventually, all of HCI will be online and freely accessible around the world.
Design of repairable and fully diagnosable folded PLAs for yield enhancement
Authors: Chin-Long Wey, Jyhyeung Ding, Tsin-Yuan Chang
Venue: Proceedings of the 27th ACM/IEEE Design Automation Conference (1991)

The yield of ICs has always been crucial to the commercial success of their manufacture. One solution to the low yield problem is to improve the manufacturing and testing processes. This is very costly and quite difficult to implement. The practical approach is to use a fault-tolerant design. In this paper, a design of repairable and fully diagnosable folded PLA is presented, in which the defects can be repaired with-out reconfiguring the external routing. The design achieves a full diagnosability of single and multiple stuck-at, bridging, and crosspoint faults, and has led to a significant yield improvement. The physical layout and floor plan are also provided to assess the chip area.
Computing A*B (mod N) efficiently in ANSI C
Authors: Henry G. Baker
Venue: ACM SIGPLAN Notices (1992)

The modular product computation A*B (mod N) is a bottleneck for some public-key encryption algorithms, as well as many exact computations implemented using the Chinese Remainder Theorem. We show how to compute A*B (mod N) efficiently, for single-precision A, B, and N, on a modern RISC architecture (Intel 80860) in ANSI C. On this architecture, our method computes A*B (mod N) faster than ANSI C computes A%N, for unsigned longs A and N.
Munin: distributed shared memory using multi-protocol release consistency
Authors: Willy Zwaenepoel, John K. Bennett, John B. Carter, Pete Keleher
Venue: IEEE Computer Society Technical Committee Newsletter on Operating Systems and Application Environments (1992)

Munin is a distributed shared memory system that allows parallel programs written for shared memory multiprocessors to be executed efficiently on distributed memory multiprocessors. Unlike existing DSM systems, which provide only a single memory consistency mechanism, Munin provides a suite of consistency protocols. The consistency protocol to be used with a particular shared object is specified by annotating the declaration of the object in the source program. Munin is furthermore the first DSM system to implement release consistency, a relaxed form of memory consistency. Release consistency allows network latency to be masked, and significantly reduces the number of messages required to keep memory consistent. Munin's multi-protocol release consistency is implemented entirely in software. At the heart of the implementation is a delayed update queue, that buffers and merges pending remote writes. A prototype implementaiton on an Ethernet network of 16 SUN-3 processors indicates good performance, without having to make major modifications to the shared memory programs. Further work will include implementation of a second prototype on a high-performance architecture, investigation of hardware support, a port to Mach, and new applciations andd languages to Munin.
The internet society announcing a new organization
Authors: Leila Lyons, Ann Amsler
Venue: ACM SIGUCCS Newsletter (1991)

The purpose of this document is to provide a brief description of the Internet Society and its goals and objectives. It will function as a professional society to facilitate, support, and promote the evolution and growth of the Internet as a global research communications infrastructure. The suggestions and recommendations of all parties interested in the Internet are solicited to assist in making the Internet Society robust, productive, and structured to meet the needs of its members.