ppxscal/embedding_network huggingface dataset:
Needed: a meta-language for evaluating the expressiveness of EDIF, IGES, VHDL and other representation mechanisms
Authors: M. L. Brei
Venue: Proceedings of the 24th ACM/IEEE Design Automation Conference (1987)

The IEEE/CS/DASS Electronic Model Working Group (EMG) is using data modeling methodologies to analyze the interoperability of existing exchange formats for electronic product data. The operational philosophy of the EMG is that a conceptual schema for shared product data can serve as a meta-language and foundation for CAE/CAD/CIM data integration.
Bounding Signal Probabilities in Combinational Circuits
Authors: G. Markowsky
Venue: IEEE Transactions on Computers (1987)

In [2] Savir, Ditlow, and Bardell presented an algorithm for estimating the signal probability of a line in combinational circuits, but were unable to show that the algorithm always produced correct results. This paper shows that their algorithm for cutting reconvergent fan-out lines in a circuit eventually produces a circuit without reconvergent fan- out that can be used to estimate signal probabilities in all lines of the original circuit.
Fast algorithms for computing the largest empty rectangle
Authors: A. Aggarwal, S. Suri
Venue: Proceedings of the third annual symposium on Computational geometry (1987)

We provide two algorithms for solving the following problem: Given a rectangle containing n points, compute the largest-area and the largest-perimeter subrectangles with sides parallel to the given rectangle that lie within this rectangle and that do not contain any points in their interior. For finding the largest-area empty rectangle, the first algorithm takes &Ogr;(n log3 n) time and &Ogr;(n) memory space and it simplifies the algorithm given by Chazelle, Drysdale and Lee which takes &Ogr;(n log3 n) time but &Ogr;(n log n) storage. The second algorithm for computing the largest-area empty rectangle is more complicated but it only takes &Ogr;(n log2 n) time and &Ogr;(n) memory space. The two algorithms for computing the largest-area rectangle can be modified to compute the largest-perimeter rectangle in &Ogr;(n log2 n) and &Ogr;(n log n) time, respectively. Since &OHgr;(n log n) is a lower bound on time for computing the largest-perimeter empty rectangle, the second algorithm for computing such a rectangle is optimal within a multiplicative constant.
An efficient new algorithm for 2-D line clipping: Its development and analysis
Authors: Tina M. Nicholl, D. T. Lee, Robin A. Nicholl
Venue: Proceedings of the 14th annual conference on Computer graphics and interactive techniques (1987)

This paper describes a new alorithm for clipping a line in two dimensions against a rectangular window. This algorithm avoids computation of intersection points which are not endpoints of the output line segment. The performance of this algorithm is shown to be consistently better than existing algorithms, including the Cohen-Sutherland and Liang-Barsky algorithms. This performance comparison is machine-independent, based on an analysis of the number of arithmetic operations and comparisons required by the different algorithms. We first present the algorithm using procedures which perform geometric transformations to exploit symmetry properties and then show how program transformation techniques may be used to eliminate the extra statements involved in performing geometric transformations.
Incremental data-flow analysis algorithms
Authors: Barbara G. Ryder, Marvin C. Paull
Venue: ACM Transactions on Programming Languages and Systems (TOPLAS) (1988)

An incremental update algorithm modifies the solution of a problem that has been changed, rather than re-solving the entire problem. ACINCF and ACINCB are incremental update algorithms for forward and backward data-flow analysis, respectively, based on our equations model of Allen-Cocke interval analysis. In addition, we have studied their performance on a &ldquo;nontoy&rdquo; structured programming language L. Given a set of localized program changes in a program written in L, we identify a priori the nodes in its flow graph whose corresponding data-flow equations may be affected by the changes. We characterize these possibly affected nodes by their corresponding program structures and their relation to the original change sites, and do so without actually performing the incremental updates. Our results can be refined to characterize the reduced equations possibly affected if structured loop exit mechanisms are used, either singly or together, thereby relating richness of programming language usage to the ease of incremental updating.
Checkpoint repair for out-of-order execution machines
Authors: W. W. Hwu, Y. N. Patt
Venue: Proceedings of the 14th annual international symposium on Computer architecture (1987)

Out-of-order execution and branch prediction are two mechanisms that can be used profitably in the design of Supercomputers to increase performance. Unfortunately this means there must be some kind of repair mechanism, since situations do occur that require the computing engine to repair to a known previous state. One way to handle this is by checkpoint repair. In this paper we derive several properties of checkpoint repair mechanisms. In addition, we provide algorithms for performing checkpoint repair that incur very little overhead in time and modest cost in hardware. We also note that our algorithms require no additional complexity or time for use with write back cache memory systems than they do with write through cache memory systems, contrary to statements made by previous researchers.
Toward expert systems on a chip
Authors: C G Looney, A R Alfize
Venue: Issue 98 (October 1986) (1986)

1. INTRODUCTION. In this investigation we attempt to quantify expert reasoning to process boolean values 0 (FALSE) and 1 (TRUE) instead of large lists of atoms that form conditions. The human brain reasons by processing demodulated signals through axons and across synapses, which either fire or don't fire in a boolean fashion. Our approach bridges the current expert systems approach (see, e.g., Hayes-Roth et al.[3]) and the old approaches, e.g., neural nets (McCulloch and Pitts[6]) and associations (Nakano[9]). It simplifies knowledge representation by reducing much of symbolic processing to efficient ANDing and ORing. An ultimate application of our approach would be an expert systems on a chip. A side effect of this would be the demise of inefficient, memory cluttering, list processing languages.
Synchronization of Fault-Tolerant Clocks in the Presence of Malicious Failures
Authors: Nagesh Vasanthavada, Peter N. Marinos
Venue: IEEE Transactions on Computers (1988)

The problem of achieving global clock synchronization in fault-tolerant clocks by preventing so-called multiple cliques in the presence of malicious clock failures (i.e. clock failures that are perceived differently by different nonfaulty clocks) is addressed. A solution to the problem, referred to as the averaging rule, is developed, and its use is analytically justified using the notions of clock partitions and generalized clock partitions. Experimental characterization of the multiple cliques problem has been undertaken, and certain conditions that induce their occurrence in practical hardware implementation are identified. The effects of clock-receiver triggering variations and phase-detector operating range on the instantaneous frequencies of the clock modules are investigated. The efficacy of the averaging rule is established not only by analysis but also by means of simulations and experimentation with hardware clock implementations.
&ldquo;I've got a quick question..." or, a dozen years of network user services
Authors: Christine Wendt
Venue: Proceedings of the 15th annual ACM SIGUCCS conference on User Services (1987)

The lead-in never changes, but the &ldquo;quick&rdquo; questions do. In 12 years at the Merit Computer Network, the quick questions have tended to come in waves whose nature has changed dramatically as the nature of network usage and network services has changed.
Learning and transfer for text and graphics editing with a direct manipulation interface
Authors: J. E. Ziegler, H. U. Hoppe, K. P. Fahnrich
Venue: ACM SIGCHI Bulletin (1986)

For a Direct Manipulation interface, transfer of skill between text and graphics editing tasks has been investigated. A learning experiment has been carried out with two groups of novice users starting with a series of sessions in one task domain and then switching over to the other domain. The empirical results are discussed in the framework of the &ldquo;cognitive complexity&rdquo; theory of Polson and Kieras.
Experiences with the alternate reality kit: an example of the tension between literalism and magic
Authors: Randall B. Smith
Venue: ACM SIGCHI Bulletin (1986)

This paper presents an overview of the Alternate Reality Kit (ARK), an animated environment for creating interactive simulations. ARK is built upon a physical-world metaphor: all objects have an image, a position, a velocity, and can experience forces. Users manipulate objects with a mouse-operated &ldquo;hand&rdquo; which enables them to carry and throw objects, to press buttons, and to operate sliders.The interface features are discussed in light of a general user interface tension between literalism and magic. Literal features are defined to be those that are true to the interface's metaphor. Literal features enhance an interface's learnability. Magical features are defined to be those capabilities that deliberately violate the metaphor in order to provide enhanced functionality. Discussion of each ARK feature includes informal observations of early ARK users, an assessment of the feature's learnability, of its usefulness, and of its position on the magical-literal axis.Even though ARK includes magical features, applications-level users have be trained in a few minutes. Although this paper is about ARK, the tension between literalism and magic raises some interesting questions on its own. Some of these questions are presented briefly in the conclusion.
Hairy brushes
Authors: Steve Strassmann
Venue: ACM SIGGRAPH Computer Graphics (1986)

Paint brushes are modeled as a collection of bristles which evolve over the course of the stroke, leaving a realistic image of a sumi brush stroke. The major representational units are (1) Brush: a compound object composed of bristles, (2) Stroke: a trajectory of position and pressure, (3) Dip: a description of the application of paint to a class of brushes, and (4) Paper: a mapping onto the display device. This modular system allows experimentation with various stochastic models of ink flow and color change. By selecting from a library of brushes, dips, and papers, the stroke can take on a wide variety of expressive textures.
On the Church-Rosser property for the direct sum of term rewriting systems
Authors: Yoshihito Toyama
Venue: Journal of the ACM (JACM) (1987)

The direct sum of two term rewriting systems is the union of systems having disjoint sets of function symbols. It is shown that if two term rewriting systems both have the Chruch-Rosser property, then the direct sum of these systems also has this property.
Attention, intentions, and the structure of discourse
Authors: Barbara J. Grosz, Candace L. Sidner
Venue: Computational Linguistics (1986)

In this paper we explore a new theory of discourse structure that stresses the role of purpose and processing in discourse. In this theory, discourse structure is composed of three separate but interrelated components: the structure of the sequence of utterances (called the linguistic structure), a structure of purposes (called the intentional structure), and the state of focus of attention (called the attentional state). The linguistic structure consists of segments of the discourse into which the utterances naturally aggregate. The intentional structure captures the discourse-relevant purposes, expressed in each of the linguistic segments as well as relationships among them. The attentional state is an abstraction of the focus of attention of the participants as the discourse unfolds. The attentional state, being dynamic, records the objects, properties, and relations that are salient at each point of the discourse. The distinction among these components is essential to provide an adequate explanation of such discourse phenomena as cue phrases, referring expressions, and interruptions.The theory of attention, intention, and aggregation of utterances is illustrated in the paper with a number of example discourses. Various properties of discourse are described, and explanations for the behavior of cue phrases, referring expressions, and interruptions are explored.This theory provides a framework for describing the processing of utterances in a discourse. Discourse processing requires recognizing how the utterances of the discourse aggregate into segments, recognizing the intentions expressed in the discourse and the relationships among intentions, and tracking the discourse through the operation of the mechanisms associated with attentional state. This processing description specifies in these recognition tasks the role of information from the discourse and from the participants' knowledge of the domain.
Virtual Time CSMA Protocols for Hard Real-Time Communication
Authors: W. Zhao, K. Ramamritham
Venue: IEEE Transactions on Software Engineering (1987)

We study virtual time CSMA protocols for hard real time communication systems, i, e., systems where messages have explicit deadlines. In this class of CSMA protocols, each node maintains two clocks; a real time clock and a virtual time clock. Whenever a node finds the channel to be idle, it resets its virtual clock. The virtual clock then runs at a higher rate than the real clock. A node transmits a waiting message when the time on the virtual clock is equal to some parameter of the message. Using different message parameters in conjunction with the virtual clock, different transmission policies can be implemented. In particular, use of message arrival time, message length, message laxity, and message deadline implements FCFS, Minimum-Length-First, Minimum-Laxity-First, and Minimum-Deadline-First transmission policies, respectively.
Generating Fractal-Like Surfaces on General Purpose Mesh-Connected Computers
Authors: Michael Wainer
Venue: IEEE Transactions on Computers (1988)

Realistic images of natural surfaces are often generated using computationally expensive stochastic modeling techniques. A parallel procedure to generate such models is presented. The target machines are general-purpose mesh-connected computers. The complexity of the procedure is similar to that of a proposed special-purpose parallel fractal generator.
Designing user services on a PC LAN
Authors: Kevin Lacoble
Venue: Proceedings of the 15th annual ACM SIGUCCS conference on User Services (1987)

Personal Computer (PC) Local Area Networks (LANs) have gained a lot of press attention recently. PC use has proliferated in many businesses and schools, and LANs provide connectivity opportunities for these formerly isolated computers. Commercial LAN hardware has been on the market for several years, and has matured sufficiently to be reliable and cost effective. Recently, Microsoft developed the Network Basic Operating System (NETBIOS), and it promises to standardize the PC LAN market in much the same way that Microsoft's Disk Operating System (DOS) has done for PCs. The most efficacious use of these new LANs would be one that emphasize its unique characteristics. These characteristics can be summarized as: Employs PCs as the main nodes of the network. Provides peer-to-peer communication services. Allows sharing of PC peripherals, such as printers and hard disks. Uses DOS as its base. Runs software based upon earlier, stand-alone versions of DOS. The new DOS-based networks are ideally designed for general purpose user services. Specific retail or industrial applications are still best solved by multi-user systems with terminals. It is when the computing needs are diverse that a PC LAN, with its ability to run the thousands of software packages already available for DOS, is best suited. With the idea of providing user services on a PC LAN established, it is helpful to examine what current LAN software provides. NET software1 has seemingly developed in the same, infamous, way of DOS, and thus may have some deficiencies to correct before being successfully used.
Formal methods and formal description techniques: their understanding, development, support and use in the context of ESPRIT
Authors: R. Jacquart
Venue: Proceedings of the 1987 Fall Joint Computer Conference on Exploring technology: today and tomorrow (1987)

The need to support the whole process of system development with formal notations, methods and their associated tools is a major topic in the Software Technology Workplan of the ESPRIT program. A number of projects have been launched during the first 3 years in order to insure a satisfactory coverage of this workplan area. Some of them in this area have short term objectives, as such they emphasize the use and support of existing methods. Others are research oriented: they are faced with the problems of development and of understanding (formalizing the use) of classical or new methods. This paper surveys methods and techniques used or developed in representative ESPRIT projects in the S. T. area.
The standards factor
Authors: Jon Meads
Venue: ACM SIGCHI Bulletin (1987)

Not much news has come by my desk since the last article in the January Bulletin. The Human Factors Society had its standards group meet at CHI+GI '87. Unfortunately, I was not able to attend due to conflicting responsibilities.
A case study in test environment evolution
Authors: K. F. Donnelly, K. A. Gluck
Venue: ACM SIGSOFT Software Engineering Notes (1988)

As the demand for increasingly complex software systems grows, and our software development environments become increasingly sophisticated in response, our testing technology must keep pace. This paper describes the evolution of one software testing environment and the genesis of its logical successor.pastel (PICS Automated System Testing Environment for Leap) originated over a decade ago, with an interpreter for a simple testing language used on a single project by a group of about ten people. As the demands of testing very large systems grew, pastel's functionality expanded. Today's pastel includes facilities for creating a test by simply exercising the system under test, for running the test in a variety of modes, and for capturing and automatically analyzing test results. pastel allows application experts to create tests easily; no sophisticated programming skill is required. pastel is now used by projects throughout the Software Technology and Systems Area of Bell Communications Research.pastel is a relatively mature product, an adequate testing system for the monolithic database systems it was intended to exercise. astra, its successor, is now being designed to test systems of interacting systems built on different sizes and flavors of hardware. This paper reviews the evolution of pastel and the preliminary design work and unifying concepts underlying astra.
Some Comments on "Transition-Oriented" Versus "Structured" Specification of Distributed Algorithms and Protocols
Authors: G. v. Bochman, J. P. Verjus
Venue: IEEE Transactions on Software Engineering (1987)

Formal description techniques (FDT's) are being developed for the specification of communication protocols and other distributed systems. Some of them (namely SDL and Estelle) are based on an extended state transition model and promote a "transition-oriented" specification style. Another one (namely Lotos) and most highlevel programming languages promote a style which is called "structured." The correspondence compares these two specification styles in the framework of rendezvous interactions between different system modules. The advantages of each of the two styles are discussed in relation with an example of a virtual ring mutual exclusion protocol. Transformation rules between the two approaches are given. An extension to the state transition oriented FDT's is also suggested in order to allow for a structured specification style.
On user interface reference models
Authors: Keith A Lantz
Venue: ACM SIGCHI Bulletin (1986)

The proliferation of personal workstations and computer networks has enabled users to develop or otherwise access an ever wider range of applications. Unfortunately, the human-computer interface has not kept pace with the available hardware, nor with the aspirations of many users. Major advances are required with respect to the "style" of human-computer interaction -- advances in graphical techniques as well as other communications media. Moreover, this "style" should be as consistent as possible across applications. Much work remains to be done in achieving this consistency in the face of the wide variety of applications currently available. At the implementation level, much work remains to be done to accommodate heterogeneous hardware and software bases. For example, to what extent can we ensure that applications can run as well distributed over low-speed lines as over high-speed local area networks? How might we implement the human-computer interface in such a way as to be easily ported to a variety of operating systems, not just to a variety of machines running the same operating system?
On shortest paths amidst convex polyhedra
Authors: A Sharir, A Baltsan
Venue: Proceedings of the second annual symposium on Computational geometry (1986)

We consider the problem of computing the Euclidean shortest path between two points in three-dimensional space which must avoid the interiors of k given disjoint convex polyhedral obstacles, having altogether n faces. Although this problem is hard to solve when k is arbitrarily large, it had been efficiently solved by Mount [Mo84] (cf. also Sharir and Schorr [SS84]) for k = 1, i.e. in the presence of a single convex polyhedral obstacle, in time &Ogr;(n2log n). In this paper we consider the generalization of this technique to the cases k = 2 and k > 2. In the first part of this presentation we describe an algorithm which calculates shortest paths amidst two convex polyhedral obstacles in time &Ogr;(n3&agr;(n)&Ogr;(&agr;(n)7)log n), where &agr;(n) is the functional inverse of Ackermann's function (and is thus extremely slowly growing). This result is achieved by constructing a new kind of Voronoi diagram, called peeper's Voronoi diagram, which is introduced and analyzed here. In the second part we show that shortest paths amidst k > 2 disjoint convex polyhedral obstacles can be calculated in time polynomial in the total number n of faces of these obstacles (but exponential in the number of obstacles). This is a consequence of the following result: Let K be a 3-D convex polyhedron having n vertices. Then the number of shortest-path edge sequences on K is polynomial in n (specifically &Ogr;(n7)), where a shortest-path edge sequence &xgr; is a sequence of edges of K for which there exist two points X, Y on the surface S of K such that &xgr; is the sequence of edges crossed by the shortest path from X to Y along S.
Implementation aids for optimization algorithms that solve sequences of linear programs
Authors: J. L. Nazareth
Venue: ACM Transactions on Mathematical Software (TOMS) (1986)

We describe a collection of modules designed to facilitate the implementation of optimization (LP) algorithms that must solve one or more linear programs in a suitably coordinated sequence. Our collection also provides a basis for discussing some of the broader issues of LP software development and serves as a tutorial on state-of-the-art techniques that may be used to implement LP algorithms in a practical manner.