ppxscal/embedding_network huggingface dataset:
Selecting the checkpoint interval in time warp simulation
Authors: Yi-Bing Lin, Bruno R. Preiss, Wayne M. Loucks, Edward D. Lazowska
Venue: ACM SIGSIM Simulation Digest (1993)

In Time Warp parallel simulation, the state of each process must be saved (checkpointed) regularly in case a rollback is necessary. Although most existing Time Warp implementations checkpoint after every state transition, this is not necessary, and the checkpoint interval is in reality a tuning parameter of the simulation. Lin and Lazowska[6] proposed a model to derive the optimal checkpoint interval by assuming that the rollback behavior of Time Warp is not affected by the frequency of checkpointing. An experimental study conducted by Preiss et al.[10] indicates that the behavior of rollback is affected by the frequency of checkpointing in general, and that the Lin-Lazowska model may not reflect the real situations in general. This paper extends the Lin-Lazowska model to include the effect of the checkpoint interval on the rollback behavior. The relationship among the checkpoint interval, the rollback behavior, and the overhead associated with state saving and restoration is described. A checkpoint interval selection algorithm which quickly determines the optimal checkpoint interval during the execution of Time Warp simulation is proposed. Empirical results indicate that the algorithm converges quickly and always selects the optimal checkpoint interval.
Towards a theory of spatial database queries (extended abstract)
Authors: Jan Paredaens, Jan Van den Bussche, Dirk Van Gucht
Venue: Proceedings of the thirteenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems (1994)

A general model for spatial databases is considered, which extends the relational model by allowing as tuple components not only atomic values but also geometrical figures. The model, which is inspired by the work of Kanellakis, Kuper and Revesz on constraint query languages, includes a calculus and an algebra which are equivalent. Given this framework, the concept of spatial database query is investigated. Thereto, Chandra and Harel's well-known consistency criterion for classical relational queries is adapted. Various adaptations are proposed, depending on the kinds of geometry in which the spatial information in the database is to be interpreted. The consistency problem for calculus queries is studied. Expressiveness issues are examined. The main purpose of the paper is to open up new grounds for theoretical research in the area of spatial database systems. Consequently, many open problems are indicated.
Extending device management in Minix
Authors: C. Kavka, M. Printista, R. Gallard
Venue: ACM SIGOPS Operating Systems Review (1993)

Minix is a Unix clone Operating System, designed by Tanembaum ([2],[3]) to allow beginners to do practical training in Operating Systems area. In this context the present paper describes the work done by a group of undergraduates implementing extensions in device management. Problems in the original code, detected during the analysis and development stages, are also reported.
ALBA: a parallel language based on actors
Authors: J. Hernández, P. de Miguel, M. Barrena, J. M. Martínez, A. Polo, M. Nieto
Venue: ACM SIGPLAN Notices (1993)

In this paper, ALBA, A parallel Language Based on Actors, is introduced. ALBA [15] is a new programming language designed to take advantage of highly parallel architectures that use message passing as the fundamental low-level interaction primitive. ALBA is being developed as implementation language for the QUATRO parallel Database machine [5] in order to facilitate its portability and permit a homogeneous description of the QUATRO system to every multiprocessor machine.ALBA is a strong-typed language, and is oriented towards the development of both parallel and distributed applications. The actor paradigm in ALBA presents new characteristics such as the use of broadcast methods; dynamic actor allocations permitting the programmer to distribute actors on the machine, in a load-balancing way, on both a specific set of virtual processors or on all of the processors of the machine; different communication and synchronization mechanisms among actors, and others that are presented in this papcr.The ALBA programming language and the QUATRO Database Machine are being developed under the HELIOS operating system for a transputer machine.
Dominance range-query: the one-reporting case
Authors: Thomas Dubé
Venue: Proceedings of the ninth annual symposium on Computational geometry (1993)

Problems which arise naturally in computer algebra can be considered as geometric dominance queries in which we are required to identify only one point (if any) which lies within the query range. In this paper, we consider the differences between this problem and other more traditional range query problems. In particular we investigate the inherent complexity of this problem and data structures which can be used for answering this query.
Storage and network requirements of a low-cost computer-based virtual classroom
Authors: Paul Juell, Daniel Brekke, Ronald Vetter, John Wasson
Venue: ACM SIGSOFT Software Engineering Notes (1994)

In this paper we investigate the network and storage requirements of a virtual classroom. The virtual classroom replaces traditional class methodologies by using the computer as the sole instrument for all class activity. The instructor and the students each have a networked workstation in an X cluster that provides for the creation, modification, and distribution of presentations, note-taking, capturing of presentation material, out-of-class reviewing of presentation material, and viewing of supplemental materials provided by the instructor (including selected readings, exams, and assignments).We have designed and implemented an virtual classroom as a means of enhancing the teaching/learning process. The creation of this virtual classroom was accomplished by using only existing computing resources: SUN workstations, X tools, an Ethernet network, and UNIX operating system support. Network statistics were collected to determine how well existing networks can be utilized within this environment. We also observed the performance of the system in a realistic setting by using it to teach an Office Information Systems class at North Dakota State University.
Partial orders for planarity and drawings (abstract)
Authors: Hubert de Fraysseix, Pierre Rosenstiehl
Venue: ACM SIGACT News (1993)

A bipolar orientation of a graph appears often in the algorithm literature as a first step for the generation of a particular drawing. Here the properties of bipolar orientations are systematically explored in terms of circuits, cocircuits, rank activities, Tutte polynomial, poset dimension, angle bipartition and max flow-min cut theorem. Efficient algorithms are described to list, generate or extend bipolar orientations for general graphs or plane ones, with or without constraints. (Joint work with Patrice de Mendez.)
Aslantest: a symbolic execution tool for testing Aslan formal specifications
Authors: Jeffrey Douglas, Richard A. Kemmerer
Venue: Proceedings of the 1994 ACM SIGSOFT international symposium on Software testing and analysis (1994)

This paper introduces Aslantest, a symbolic execution tool for the formal specification language Aslan. Aslan is a state-based specification language built on first-order predicate calculus with equality. Aslantest animates Aslan specifications and enables users to interactively run specific test cases or symbolically execute the specification. Testing the formal specifications early in the software life cycle allows one to assure a reliable system that also provides the desired functionality.
The licensing of computer professionals (abstract)
Authors: Paul Davis, George Eggert, Don Gotterbarn, Eric Roberts
Venue: Proceedings of the 1993 ACM conference on Computer science (1993)

The 1992 CSC Annual Debate produced a lively discussion focused on a resolution calling upon the ACM to support efforts in state legislatures to regulate and license computer professionals. This followed proposals in several states for just such licensing. Meanwhile, the IEEE computer society committee on public policy has drafted a position statement endorsing &ldquo;a national policy on the certification of safety-critical software by licensed, professional Software Engineers.&rdquo; Do ACM members support the licensing of computer professionals? To what degree will such licensing ensure quality software or better testing? And can the abilities and responsibility of software engineers or programmers really be objectively measured? The distinguished panelists will address these issues in what is certain to be a frank and free-wheeling exchange with each other and with the audience.
Generating a test oracle from program documentation: work in progress
Authors: Dennis Peters David L. Parnas
Venue: Proceedings of the 1994 ACM SIGSOFT international symposium on Software testing and analysis (1994)

A fundamental assumption of software testing is that there is some mechanism, an oracle, that will determine whether or not the results of a test execution are correct. In practice this is often done by comparing the output, either automatically or manually, to some pre-calculated, presumably correct, output [17]. However, if the program is formally documented it is possible to use the specification to determine the success or failure of a test execution, as in [1], for example. This paper discusses ongoing work to produce a tool that will generate a test oracle from formal program documentation.In [9], [10] and [11] Parnas et al. advocate the use of a relational model for documenting the intended behaviour of programs. In this method, tabular expressions are used to improve readability so that formal documentation can replace conventional documentation. Relations are described by giving their characteristic predicate in terms of the values of concrete program variables. This documentation method has the advantage that the characteristic predicate can be used as the test oracle -- it simply must be evaluated for each test execution (input output) to assign pass or fail. In contrast to [1], this paper discusses the testing of individual programs, not objects as used in [1]. Consequently, the method works with program documentation, written in terms of the concrete variables, and no representation function need be supplied. Documentation in this form, and the corresponding oracle, are illustrated by an example.Finally, some of the implications of generating test oracles from relational specifications are discussed.
Perturbation analysis of high level instrumentation for SPMD programs
Authors: Sekhar R. Sarukkai, Allen D. Malony
Venue: ACM SIGPLAN Notices (1993)

The process of instrumenting a program to study its behavior can lead to perturbations in the program's execution. These perturbations can become severe for large parallel systems or problem sizes, even when one captures only high level events. In this paper, we address the important issue of eliminating execution perturbations caused by high-level instrumentation of SPMD programs. We will describe perturbation analysis techniques for common computation and communication measurements, and show examples which demonstrate the effectiveness of these techniques in practice.
Capturing, structuring, and representing ubiquitous audio
Authors: Debby Hindus, Chris Schmandt, Chris Horner
Venue: ACM Transactions on Information Systems (TOIS) (1993)

Although talking is an integral part of collaboration, there has been little computer support for acquiring and accessing the contents of conversations. Our approach has focused on ubiquitous audio, or the unobtrusive capture of speech interactions in everyday work environments. Speech recognition technology cannot yet transcribe fluent conversational speech, so the words themselves are not available for organizing the captured interactions. Instead, the structure of an interaction is derived from acoustical information inherent in the stored speech and augmented by user interaction during or after capture. This article describes applications for capturing and structuring audio from office discussions and telephone calls, and mechanisms for later retrieval of these stored interactions. An important aspect of retrieval is choosing an appropriate visual representation, and this article describes the evolution of a family of representations across a range of applications. Finally, this work is placed within the broader context of desktop audio, mobile audio applications, and social implications.
The model, language, and implementation of an object-oriented multimedia knowledge base management system
Authors: Hiroshi Ishikawa, Fumio Suzuki, Fumihiko Kozakura, Akifumi Makinouchi, Mika Miyagishima, Yoshio Izumida, Masaaki Aoshima, Yasuo Yamane
Venue: ACM Transactions on Database Systems (TODS) (1993)

New applications such as CAD, AI, and hypermedia require direct representation and flexible use of complex objects, behavioral knowledge, and multimedia data. To this end, we have devised a knowledge base management system called Jasmine. An object-oriented approach in a programming language also seems promising for use in Jasmine. Jasmine extends the current object-oriented approach and provides the following features. Our object model is based on functional data models and well-established set theory. Attributes or functions composing objects can represent both structural and behavioral knowledge. The object model can represent incomplete and generic knowledge. The model can support the basic storage and operations of multimedia data. The facets of attributes can flexibly represent constraints and triggers. The object manipulation language can support associative access of objects. The structural and behavioral knowledge can be uniformly treated to allow the user to specify complex object operations in a compact manner. The user-defined and system-defined attributes can be uniformly specified to ease user customization of the language. The classes and instances can be uniformly accessed. Incomplete knowledge can be flexibly accessed. The system has a layered architecture. Objects are stored in nested relations provided by extensive DBMS as a sublayer. User query of objects is compiled into relational operations such as select and join, which can be efficiently processed using hashing. The behavioral knowledge is compiled into predicate and manipulation function interfaces that can directly access tuples in a buffer. &mdash;Authors' Abstract
On Subgraphs in Distance-Regular Graphs
Authors: J. H. Koolen
Venue: Journal of Algebraic Combinatorics: An International Journal (1992)

Terwilliger &lsqb;15&rsqb; has given the diameter bound d &le; (s &minus; 1)(k &minus; 1) + 1 for distance-regular graphs with girth 2s and valency k. We show that the only distance-regular graphs with even girth which reach this bound are the hypercubes and the doubled Odd graphs. Also we improve this bound for bipartite distance-regular graphs. Weichsel &lsqb;17&rsqb; conjectures that the only distance-regular subgraphs of a hypercube are the even polygons, the hypercubes and the doubled Odd graphs and proves this in the case of girth 4. We show that the only distance-regular subgraphs of a hypercube with girth 6 are the doubled Odd graphs. If the girth is equal to 8, then its valency is at most 12.
An equational language for data-parallelism
Authors: Pushpa Rao, Clifford Walinsky
Venue: ACM SIGPLAN Notices (1993)

Data-parallelism provides a clean conceptual framework for parallel programming. We are developing two programming languages: a high level equational language, called EL*, and a low-level implementation language. Both languages exploit data-parallelism instead of control-parallelism. EL* is a declarative data-parallel language. EL* programs are high-level equational specifications that use extensive pattern-matching and recursion. The language's syntax and semantics are intended to be clear and simple. Recursive forms are restricted to enable translation to efficient data-parallel operations. EL* programs are compiled into FP*, a variant of Backus's FP, where parallel operations are more explicit and low-level. The target language has a rich set of functions for performing communication, and computation. It also has a powerful set of combining forms that generate large highly-parallel functions from smaller program units. Prototype compilers have been implemented for both languages, and they demonstrate good performance. Several linear algebra and non-numeric problems have been programmed with relative ease using EL*. We are currently developing compilation techniques for a wider range of scientific problems that have more complex parallel solutions, and are continuing to expand the language's scope.
A protocol processing architecture for networked multimedia computers
Authors: R. Gopalakrishnan, Andreas D. Bovopoulos
Venue: ACM SIGOPS Operating Systems Review (1993)

Multimedia workstation architectures differ from current architectures in these respects --- they have multiple specialized processing units, a high speed I/O interconnect mechanism, a high speed broadband network interface and a real-time multitasking operating system (OS) that provides QoS guarantees. These systems will primarily be used to run distributed applications that require high network throughput and predictable delay and delay jitter for real-time traffic. We argue the need for a different protocol organization and processing architecture in order to achieve this. We show how the emerging hardware architecture and OS structures favor a "decentralized protocol processing" approach, that takes advantage of the data delivery mechanism provided by the hardware to improve in-band (protocol data) processing, and the sophisticated OS mechanisms based on communicating objects to improve the out-of band (control) processing. We discuss the need for providing end-to-end QoS guarantees for applications and discuss how it can be naturally incorporated in the proposed architecture.
Improving the cache locality of memory allocation
Authors: Dirk Grunwald, Benjamin Zorn, Robert Henderson
Venue: Proceedings of the ACM SIGPLAN 1993 conference on Programming language design and implementation (1993)

The allocation and disposal of memory is a ubiquitous operation in most programs. Rarely do programmers concern themselves with details of memory allocators; most assume that memory allocators provided by the system perform well. This paper presents a performance evaluation of the reference locality of dynamic storage allocation algorithms based on trace-driven simualtion of five large allocation-intensive C programs. In this paper, we show how the design of a memory allocator can significantly affect the reference locality for various applications. Our measurements show that poor locality in sequential-fit allocation algorithms reduces program performance, both by increasing paging and cache miss rates. While increased paging can be debilitating on any architecture, cache misses rates are also important for modern computer architectures. We show that algorithms attempting to be space-efficient by coalescing adjacent free objects show poor reference locality, possibly negating the benefits of space efficiency. At the other extreme, algorithms can expend considerable effort to increase reference locality yet gain little in total execution performance. Our measurements suggest an allocator design that is both very fast and has good locality of reference.
Blocking for external graph searching
Authors: Mark H. Nodine, Michael T. Goodrich, Jeffrey Scott Vitter
Venue: Proceedings of the twelfth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems (1993)

In this paper, we consider the problem of using disk blocks efficiently in searching graphs that are too large to fit in internal memory. Our model allows a vertex to be represented any number of times on the disk in order to take advantage of redundancy. We give matching upper and lower bounds for complete d-ary trees and d-dimensional grid graphs, as well as for classes of general graphs that intuitively speaking have a close to uniform number of neighbors around each vertex. We also show that for the special case of grid graphs blocked with isothetic hypercubes, there is a provably better speed-up if even a small amount of redundancy is permitted.
A speech-act-based negotiation protocol: design, implementation, and test use
Authors: Man Kit Chang, Carson C. Woo
Venue: ACM Transactions on Information Systems (TOIS) (1994)

Existing negotiation protocols used in Distributed Artificial Intelligence (DAI) systems rarely take into account the results from negotiation research. We propose a negotiation protocol, SANP (Speech-Act-based Negotiation Protocol), which is based on Ballmer and Brennenstuhl's speech act classification and on negotiation analysis literature. The protocol is implemented as a domain-independent system using Strudel, which is an electronic mail toolkit. A small study tested the potential use of the protocol. Although a number of limitations were found in the study, the protocol appears to have potential in domains without these limitations, and it can serve as a building block to design more general negotiation protocols.
Algorithms for Computing Bases for the Perron Eigenspace with PrescribedNonnegativity and Combinatorial Properties
Authors: Michael Neumann, Hans Schneider
Venue: SIAM Journal on Matrix Analysis and Applications (1994)

Let $P$ be an $n \times n$ nonnegative matrix. In this paper the authors introduce a method called the SCANBAS algorithm for computing a union of (Jordan) chains $\cal{C}$ corresponding to the Perron eigenvalue of $P$, such that $\cal{C}$ consists of nonnegative vectors only and such that at each height, $\cal{C}$ contains the maximal number of nonnegative vectors of that height possible in a height basis for the Perron eigenspace of $P$. It is further shown that $\cal{C}$ can be extended to a height basis for the Perron eigenspace of $P$. The chains are extracted from transform components of $P$ that are, in turn, polynomials in $P$. When the Perron eigenspace has a Jordan basis consisting of nonnegative vectors only, this algorithm computes such a basis. The paper concludes with various examples computed by the algorithm using MATLAB. The work here continues and deepens work on computing nonnegative bases for the Perron eigenspace from polynomials in the matrix already begun by Hartwig, Neumann, and Rose and by Neumann and Schneider.
Connect 4 as a problem in artificial intelligence and robotics
Authors: Brian L. Stuart
Venue: ACM SIGCSE Bulletin (1994)

This report presents work done by the Artificial Intelligence and Robotics class of Summer Scholars 1993 at Rhodes College. Summer Scholars provides college credit for intensive two-week courses taken by high school students. The goal of this course was to develop software to play the game Connect 4 and to control a robotic arm making the moves.
On the outer: women in computer science courses
Authors: Claire Toynbee
Venue: ACM SIGACT News (1993)

After more than three years researching the question "Why women drop computer science" at Victoria University of Wellington in New Zealand, I am surprised so many women succeed given the overwhelming odds against them. Women who take computer science are 'different' not simply because they are women, but because they have chosen a subject which has been primarily a male domain. Once enrolled, they find themselves 'on the outer', facing difficulties not usually experienced by white middle class men who take computer science. There is evidence that other minorities also suffer alienation in what is essentially a distinct subculture whose origins will be discussed later.