ppxscal/embedding_network huggingface dataset:
Parallel Visualization Algorithms: Performance and Architectural Implications
Authors: Jaswinder Pal Singh, Anoop Gupta, Marc Levoy
Venue: Computer (1994)

Recently, a new class of scalable, shared-address-space multiprocessors has emerged. Like message-passing machines, these multiprocessors have a distributed interconnection network and physically distributed main memory. However, they provide hardware support for efficient implicit communication through a shared address space, and they automatically exploit temporal locality by caching both local and remote data in a processor's hardware cache. In this article, we show that these architectural characteristics make it much easier to obtain very good speedups on the best known visualization algorithms. Simple and natural parallelizations work very well, the sequential implementations do not have to be fundamentally restructured, and the high degree of temporal locality obviates the need for explicit data distribution and communication management. We demonstrate our claims through parallel versions of three state-of-the-art algorithms: a recent hierarchical radiosity algorithm by Hanrahan et al. (1991), a parallelized ray-casting volume renderer by Levoy (1992), and an optimized ray-tracer by Spach and Pulleyblank (1992). We also discuss a new shear-warp volume rendering algorithm that provides the first demonstration of interactive frame rates for a 256/spl times/256/spl times/256 voxel data set on a general-purpose multiprocessor.
HotDraw (abstract): a structured drawing editor framework for Smalltalk
Authors: Ralph Johnson
Venue: ACM SIGPLAN OOPS Messenger (1993)

HotDraw is a framework for structured drawing editors that has been floating around the Smalltalk community for several years under several incarnations. It was originally developed by Kent Beck and Ward Cunningham, but has been reimplemented many times since then. Most of these implementations were proprietary. Our design extends the original one by making constraints more composable and by adding metafigures, but the system is instantly recognizable by anyone familiar with one of the earlier implementations. We wrote a version of HotDraw for ObjectWorks\Smalltalk Release 4.0 that we are distributing. We will describe and demonstrate the basic framework and several applications built from it, such as a visual programming language, a tool for inspecting Smalltalk objects by drawing pictures of them, an environment for learning Smalltalk by issuing commands and writing scripts for visible objects, and a PERT chart editor. These applications illustrate several advanced Smalltalk techniques, such as light-weight classes, compiling code on the fly, and dynamically redirecting messages by overriding doesNotUnderstand:. Time permitting, well explore the implementation of HotDraw and how it uses these techniques.
Basic Derivations for Subarrangements of Coxeter Arrangements
Authors: Tadeusz Józefiak, Bruce E. Sagan
Venue: Journal of Algebraic Combinatorics: An International Journal (1993)

We prove that various subarrangements of Coxeter hyperplane arrangements are free. We do this by exhibiting a basis for the corresponding module of derivations. Our method uses a theorem of Saito &lsqb;24&rsqb; and Terao &lsqb;30&rsqb; which checks for a basis using certain divisibility and determinantal criteria. As a corollary, we find the roots of the characteristic polynomials for these arrangements, since they are just one more than the degrees in any basis of the module. We will also see some interesting applications of symmetric and supersymmetric functions along the way.
Implicit-specification errors and automatic, trace-based debugging
Authors: Edward G. Okie, James D. Arthur
Venue: Proceedings of the 1993 ACM conference on Computer science (1993)

Students learning computer organization and assembly language programming often have difficulty understanding the relationship between hardware functions and software instructions. This paper describes how a software tool can help students understand the organization and use of the Motorola 68000 processor family. XSIM68K employs a graphical interface to enhance a traditional &ldquo;black box&rdquo; simulator so that students can observe first-hand the effect of a running program on registers, memory, and I/O devices. Multiple data representations allow the student to choose the most appropriate format for data entry and display, which reduces confusion and eliminates conversion mistakes.
Finite Automata Computing Real Functions
Authors: Karel Culik,  II, Juhani Karhumaki
Venue: SIAM Journal on Computing (1994)

A new application of finite automata as computers of real functions is introduced. It is shown that even automata with a restricted structure compute all polynomials, many fractal-like and other functions. Among the results shown, the authors give necessary and sufficient conditions for continuity, show that continuity and equivalence are decidable properties, and show how to compute integrals of functions in the automata representation.
Distributed algorithm for K-entries to critical section based on the directed graphs
Authors: Mohamed Naimi
Venue: ACM SIGOPS Operating Systems Review (1993)

This paper proposes a token based mutual exclusion algorithm for distributed systems that allows K simultaneous entries to a critical section. In the algorithm, a logical directed graph is maintained in a connected network.This algorithm does not use sequence numbers, and the number of messages required to provide mutual exclusion, is between 0 and 2*(N-l) where N is the number of processes in the network.
HAP: a new model for packet arrivals
Authors: Ying-Dar Jason Lin, Tzu-Chieh Tsai, San-Chiao Huang, Mario Gerla
Venue: Conference proceedings on Communications architectures, protocols and applications (1993)

Applications to be supported on broadband networks exhibit a wide range of traffic statistics and many of them are sensitive to delay and loss violations. To accurately estimate admissible workload and bandwidth requirement, a detailed traffic model, HAP (Hierarchical Arrival Process) is proposed in this paper. Packets generated from HAP are modulated by processes at user, application, and message levels. This model is a generalization of on-off traffic models and is shown to be equivalent to a special class of MMPP (Markov Modulated Poisson Process). Three algorithmic methods along with simulations are applied to evaluate the queueing performance under HAP traffic. Delay under HAP traffic can be well over tens of times higher than Poisson traffic, depending on parameters and load. Congestion may persist for minutes. HAP's dramatic short-term behavior explains the occasional congestion in the real networks. Conventional traffic models, however, do not exhibit this behavior. With these results, we give implications for broadband network control.
A Distance-Regular Graph with Intersection Array (5, 4, 3, 3; 1, 1, 1, 2) Does Not Exist
Authors: D. G. Fon-Der-Flaass
Venue: Journal of Algebraic Combinatorics: An International Journal (1993)

We prove that a distance-regular graph with intersection array (5, 4, 3, 3&semi; 1, 1, 1, 2) does not exist. The proof is purely combinatorial and computer-free.
Dynamic switching of coherent cache protocols and its effects on Doacross loops
Authors: Takashi Matsumoto, Kei Hiraki
Venue: Proceedings of the 7th international conference on Supercomputing (1993)

In multiprocessor systems, overheads caused by interprocessor communication and synchronization have been one of the largest obstacles for efficient execution of parallel programs. To reduce these overheads in shared-memory/shared-bus multiprocessors, we have proposed two hardware mechanisms: the Inter-Cache Snoop Control Mechanism (ICSCM), which dynamically switches snoop-protocols for improving shared-bus utilization, and the Mechanism for Integrated Synchronization and Communication (MISC), which extends ICSCM to support producer-consumer type synchronization efficiently. We have developed an execution-driven multiprocessor simulator for evaluating performance with these mechanisms. Simulation experiments on doacross loops show remarkable speed-ups by ICSCM/MISC mechanisms. Although the proposed mechanisms are originally implemented on a single shared-bus system, they are easily applicable to a clustered multiprocessing systems. The methods used in a clustered system are discussed.
Changes in the management of the information systems organization: an exploratory study
Authors: Michael J. Gallivan
Venue: Proceedings of the 1994 computer personnel research conference on Reinventing IS : managing information technology in changing organizations: managing information technology in changing organizations (1994)

The present study was conducted as exploratory research to understand the activities and beliefs of IS and line managers, with regard to the management of information technology (IT). Semi-structured interviews were conducted with 25 managers in seven firms to understand their current initiatives, future vision, and the factors driving change. Managers from three different positions from each company were interviewed&mdash;a senior IS manager, an IS application development manager, and a line manager. The results showed that there were a variety of different initiatives underway&mdash;with the most common ones being rapid prototyping, an emphasis on purchasing packages, business reengineering, and building IT infrastructure. Beyond these few commonalities, different firms were adopting a variety of changes to their IS organization structure, working relationships with users and outside vendors, system development tools and methodologies, and their training and other human resource policies.Similarly, a broad range of factors were cited as driving changes in IT management practice&mdash;with these clustering into four major sets of drivers: business cost pressures, business service pressures, IS service pressures, and technology-push factors. Few respondents were able to articulate a vision for the IS organization of the future, beyond describing their expectations for the initiatives currently underway. Of those respondents who provided such a vision, few described the steps required to achieve the transition. These findings are analyzed in terms of a management framework derived from Harold Leavitt and discussed in light of other recent research on IS management. Questions for follow-up research are suggested.
The synchronization of periodic routing messages
Authors: Sally Floyd, Van Jacobson
Venue: ACM SIGCOMM Computer Communication Review (1993)

The paper considers a network with many apparently-independent periodic processes and discusses one method by which these processes can inadvertently become synchronized. In particular, we study the synchronization of periodic routing messages. We give examples of the harmful effect of these synchronized updates on other network traffic, and offer guidelines on how to avoid inadvertent synchronization. Using simulations and analysis, we study the process of synchronization and show that the transition from unsynchronized to synchronized traffic is not one of gradual degradation but is instead a very abrupt 'phase transition': in general, the addition of a single router will convert a completely unsynchronized traffic stream into a completely synchronized one. We show that synchronization can be avoided by the addition of randomization to the traffic sources and quantify how much randomization is necessary. In addition, we argue that the inadvertent synchronization of periodic processes is likely to become an increasing problem in computer networks.
Overfitting Avoidance as Bias
Authors: Cullen Schaffer
Venue: Machine Learning (1993)

Strategies for increasing predictive accuracy through selective pruning have been widely adopted by researchers in decision tree induction. It is easy to get the impression from research reports that there are statistical reasons for believing that these overfitting avoidance strategies do increase accuracy and that, as a research community, we are making progress toward developing powerful, general methods for guarding against overfitting in inducing decision trees. In fact, any overfitting avoidance strategy amounts to a form of bias and, as such, may degrade performance instead of improving it. If pruning methods have often proven successful in empirical tests, this is due, not to the methods, but to the choice of test problems. As examples in this article illustrate, overfitting avoidance strategies are not better or worse, but only more or less appropriate to specific application domains. We are not&mdash;and cannot be&mdash;making progress toward methods both powerful and general.
Teaching &ldquo;object think&rdquo; with multi-sensory engagement (abstract)
Authors: Peter Coad
Venue: Addendum to the proceedings on Object-oriented programming systems, languages, and applications (Addendum) (1992)

Teaching Object-Think with Multi-Sensory Engagement Peter Coad, Object International, Inc. This is a tutorial about how to teach the big picture of objects, especially in an industrial environment where time is short. It is based on the whole brain theory and multi-sensory engagement. The tutorial shows over twenty specific techniques for teaching using multi-sensory engagement, many of these unified into The Object Game, which lets those new to objects see and manipulate them. The tutorial describes a set of specific techniques for leading someone into more effective object think, and compares and contrasts whole-brain multi-sensory engagement with other "object think" techniques, such as graphics, languages, and CRC cards. This tutorial is designed for those trying to teach object-oriented development who have been frustrated by the inability of some people to reach effective object think. It will also be of interest to those planning to teach object-oriented programming, or if you are responsible for selecting such a course.
Performance comparison of thrashing control policies for concurrent Mergesorts with parallel prefetching
Authors: Kun-Lung Wu, Philip S. Yu, James Z. Teng
Venue: ACM SIGMETRICS Performance Evaluation Review (1993)

We study the performance of various run-time thrashing control policies for the merge phase of concurrent mergesorts using parallel prefetching, where initial sorted runs are stored on multiple disks and the final sorted run is written back to another dedicated disk. Parallel prefetching via multiple disks can be attractive in reducing the response times for concurrent mergesorts. However, severe thrashing may develop due to imbalances between input and output rates, thus a large number of prefetched pages in the buffer can be replaced before referenced. We evaluate through detailed simulations three run-time thrashing control policies: (a) disabling prefetching, (b) forcing synchronous writes and (c) lowering the prefetch quantity in addition to forcing synchronous writes. The results show that (1) thrashing resulted from parallel prefetching can severely degrade the system response time; (2) though effective in reducing the degree of thrashing, disabling prefetching may worsen the response time since more synchronous reads are needed; (3) forcing synchronous writes can both reduce thrashing and improve the response time; (4) lowering the prefetch quantity in addition to forcing synchronous writes is most effective in reducing thrashing and improving the response time.
Iterative methodology and designer training in human-computer interface design
Authors: Gregg "Skip" Bailey
Venue: Proceedings of the INTERACT '93 and CHI '93 conference on Human factors in computing systems (1993)

One of the most promising methods for user interface design is the iterative design methodology. To this point only case study support for this method has been given. There are still many unanswered questions about the effectiveness of this method. One difficulty encountered in user interface design is knowing what set of knowledge and skill the designer must possess to ensure good user interface design. Many different people have designed user interfaces for computer systems. These people came from a variety of backgrounds and viewpoints. Two of the most common groups involved in user interface design are human factors specialists and programmers. This study investigates these two issues. One factor in this study is the iterative design methodology. An empirical evaluation of this method was conducted. The strengths and weaknesses of this method are discussed. A second factor in this study is a comparison of human factors specialists and programmers in an actual user interface design task. The results of this study indicate that iterative design methodology can improve the usability of a product. The amount of the improvement may be constrained by the original design. This study also supports the use of human factors specialists in user interface design. A significant difference between designs produced by human factors specialists and programmers was found.
Phone-based CSCW: tools and trials
Authors: Paul Resnick
Venue: ACM Transactions on Information Systems (TOIS) (1993)

Telephones are the most ubiquitous, best-networked, and simplest computer terminals available today. They have been used for voice mail but largely overlooked as a platform for asynchronous cooperative-work applications such as event calendars, issue discussions, and question-and-answer gathering. HyperVoice is a software toolkit for constructing such applications. Its building blocks are high-level presentation formats for collections of structured voice messages. The presentation formats can themselves be presented and manipulated, enabling significant customization of applications by phone. Results of two field trials suggest social-context factors that will influence the success or failure of phone-based cooperative work applications in particular settings.
Searching in Parallel for Similar Strings
Authors: Isidore Rigoutsos, Andrea Califano
Venue: IEEE Computational Science Engineering (1994)

Distributed computation, probabilistic indexing and hashing techniques combine to create a novel approach to processing very large biological-sequence databases. Other data-intensive tasks could also benefit. Our indexing-based approach enables fast similarity searching through a large database of strings. Thanks to a redundant table-lookup scheme, recovering database items that match a test sequence requires minimal data access. We have implemented a uniprocessor version of this approach called Flash (Fast Lookup Algorithm for String Homology) as well as a distributed version, dFlash, using a cluster of seven non-dedicated workstations connected through a local area network. In this article, we present an approach for retrieving homologies in databases of proteins.
Report on the 1992 East-West international conference on human computer interaction: St. Petersburg, Russia, August 4&ndash;8
Authors: Jonathan Grudin, Allan MacLean, Scott Overmyer
Venue: ACM SIGCHI Bulletin (1993)

The East-West International Conference on Human-Computer Interaction was held August 4--8, 1992 in St. Petersburg, Russia. The second conference in an annual series, it brought together researchers from the former USSR, Europe, the United States, Japan, and Australia. At the time of the 1991 conference, the USSR was still intact (by about two weeks). By 1992 it had become the Commonwealth of Independent States and the Baltic Republics (henceforth CIS/Baltic). The conference committee settled on the more stable (if not entirely accurate) designation "East-West" to characterize the communities that came together.
Optimally profiling and tracing programs
Authors: Thomas Ball, James R. Larus
Venue: ACM Transactions on Programming Languages and Systems (TOPLAS) (1994)

This paper describes algorithms for inserting monitoring code to profile and trace programs. These algorithms greatly reduce the cost of measuring programs with respect to the commonly used technique of placing code in each basic block. Program profiling counts the number of times each basic block in a program executes. Instruction tracing records the sequence of basic blocks traversed in a program execution. The algorithms optimize the placement of counting/tracing code with respect to the expected or measured frequency of each block or edge in a program's control-flow graph. We have implemented the algorithms in a profiling/tracing tool, and they substantially reduce the overhead of profiling and tracing.We also define and study the hierarchy of profiling problems. These problems have two dimensions: what is profiled (i.e., vertices (basic blocks) or edges in a control-flow graph) and where the instrumentation code is placed (in blocks or along edges). We compare the optimal solutions to the profiling problems and describe a new profiling problem: basic-block profiling with edge counters. This problem is important because an optimal solution to any other profiling problem (for a given control-flow graph) is never better than an optimal solution to this problem. Unfortunately, finding an optimal placement of edge counters for vertex profiling appears to be a hard problem in general. However, our work shows that edge profiling with edge counters works well in practice because it is simple and efficient and finds optimal counter placements in most cases. Furthermore, it yields more information than a vertex profile. Tracing also benefits from placing instrumentation code along edges rather than on vertices.
A new method for planar graph drawings on a grid (abstract)
Authors: Goos Kant
Venue: ACM SIGACT News (1993)

Drawing graphs is an important problem that combines flavors of computational geometry and graph theory. Applications can be found in a variety of areas including circuit layout, network management, software engineering, and graphics. The main contributions of this paper can be summarized as follows: (i) We devise a model for dynamic graph algorithms, based on performing queries and updates on an implicit representation of the drawing, and we show its applications. (ii) We present several efficient dynamic drawing algorithms for trees, series-parallel digraphs, planar st-digraphs, and planar graphs. These algorithms adopt a variety of representations (e.g., straight-line, polyline, visibility), and update the drawing in a smooth way. (iii) We show that the implicit representation of the layout used by our algorithms for trees and series-parallel digraphs also supports point-location and window queries. (Joint work with P. Bertolazzi, G. Di Battista, R. Tamassia, and I. G. Tollis.)
The Concert signature representation: IDL as intermediate language
Authors: Joshua S. Auerbach, James R. Russell
Venue: ACM SIGPLAN Notices (1994)

In the Concert multilanguage distributed programming system, interface specification is the responsibility of programming languages, not a separate IDL. However, an IDL is still necessary in order to define equivalence between declarations in different languages. A single representation is also desirable internally to economize on aspects of the implementation. Consequently, Concert has an IDL as an intermediate language, produced by compiler front-ends and not normally manipulated by programmers. It is formally separated into a contract, which defines interoperability and an endpoint modifier, which captures the local choice of representation. Only contracts are used to define interface equivalence. Our choice of what kinds of information to put in the contract was motivated by a desire to be minimal, thereby enabling maximum feasible interoperability between different expressions of the same abstraction in the same or different languages.