ppxscal/embedding_network huggingface dataset:
Materialized view maintenance and integrity constraint checking: trading space for time
Authors: Kenneth A. Ross, Divesh Srivastava, S. Sudarshan
Venue: ACM SIGMOD Record (1996)

We investigate the problem of incremental maintenance of an SQL view in the face of database updates, and show that it is possible to reduce the total time cost of view maintenance by materializing (and maintaining) additional views. We formulate the problem of determining the optimal set of additional views to materialize as an optimization problem over the space of possible view sets (which includes the empty set). The optimization problem is harder than query optimization since it has to deal with multiple view sets, updates of multiple relations, and multiple ways of maintaining each view set for each updated relation.We develop a memoing solution for the problem; the solution can be implemented using the expression DAG representation used in rule-based optimizers such as Volcano. We demonstrate that global optimization cannot, in general, be achieved by locally optimizing each materialized subview, because common subexpressions between different materialized subviews can allow nonoptimal local plans to be combined into an optimal global plan. We identify conditions on materialized subviews in the expression DAG when local optimization is possible. Finally, we suggest heuristics that can be used to efficiently determine a useful set of additional views to materialize.Our results are particularly important for the efficient checking of assertions (complex integrity constraints) in the SQL-92 standard, since the incremental checking of such integrity constraints is known to be essentially equivalent to the view maintenance problem.
Supporting semantic information retrieval in communication networks by multimedia techniques
Authors: Annelise Mark Pejtersen
Venue: ACM SIGIR Forum (1995)

The aim of the project is to understand and describe the information needs and search behavior of a professional design team as a basis for formulation of specifications of an information system that effectively supports the access to a wide network of heterogeneous databases. This project will supplement a similar project focused on the needs of casual users in public libraries and thus serve to generalize from previous research. To limit the scope of the study to a realistic project, it will be focused on the activities of an industrial design team. Below follows a resume of the original project proposal.
An Implementation Framework for HPF Distributed Arrays on Message-Passing Parallel Computer Systems
Authors: Kees van Reeuwijk, Will Denissen, Henk J. Sips, Edwin M. R. M. Paalvast
Venue: IEEE Transactions on Parallel and Distributed Systems (1996)

Data parallel languages, like High Performance Fortran (HPF), support the notion of distributed arrays. However, the implementation of such distributed array structures and their access on message passing computers is not straightforward. This holds especially for distributed arrays that are aligned to each other and given a block-cyclic distribution.In this paper, an implementation framework is presented for HPF distributed arrays on message passing computers. Methods are presented for efficient (in space and time) local index enumeration, local storage, and communication.Techniques for local set enumeration provide the basis for constructing local iteration sets and communication sets. It is shown that both local set enumeration and local storage schemes can be derived from the same equation. Local set enumeration and local storage schemes are shown to be orthogonal, i.e., they can be freely combined. Moreover, for linear access sequences generated by our enumeration methods, the local address calculations can be moved out of the enumeration loop, yielding efficient local memory address generation.The local set enumeration methods are implemented by using a relatively simple general transformation rule for absorbing ownership tests. This transformation rule can be repeatedly applied to absorb multiple ownership tests. Performance figures are presented for local iteration overhead, a simple communication pattern, and storage efficiency.
The inevitable demise of the Web
Authors: Hal Berghel
Venue: ACM SIGICE Bulletin (1995)

There is no doubt that the fastest growing part of the Internet is the World Wide Web. From its inception in 1990, the Web has established itself as the leading packet hauler on the Internet, passing beyond FTP, Telnet, WAIS Gopher and all of the other, more established Internet client protocols. The reason for this success is that the Web has established itself as the standard unifying environment for the Internet's digital riches.However, the days of the Web are numbered. The technology behind the Web is outdated already and may not survive the decade. The current growth rate, which some estimate at 15% per month, suggests that if the end of the Web is to come soon, it will likely be cataclysmal. If this seems unrealistic, consider that this fate befell Gopherspace. As Figure 1 shows, Gopher lead the Web in packet volume as late as March, 1994. In the following twelve months Gopher presence on the Internet all but disappeared. Life cycles are accelerated to frightening paces on the Internet.
Using a Multipath Network for Reducing the Effects of Hot Spots
Authors: Mu-Cheng Wang, Howard Jay Siegel, Mark A. Nichols, Seth Abraham
Venue: IEEE Transactions on Parallel and Distributed Systems (1995)

One type of interconnection network for a medium to large-scale parallel processing system (i.e., a system with $2^6$ to $2^{16}$ processors) is a buffered packet-switched multistage interconnection network (MIN). It has been shown that the performance of these networks is satisfactory for uniform network traffic. More recently, several studies have indicated that the performance of MIN's is degraded significantly when there is hot spot traffic, that is, a large fraction of the messages are routed to one particular destination. A multipath MIN is a MIN with two or more paths between all source and destination pairs. This research investigates how the Extra Stage Cube multipath MIN can reduce the detrimental effects of tree saturation caused by hot spots. Simulation is used to evaluate the performance of the proposed approaches. The objective of this evaluation is to show that, under certain conditions, the performance of the network with the usual routing scheme is severely degraded by the presence of hot spots. With the proposed approaches, although the delay time of hot spot traffic may be increased, the performance of the background traffic, which constitutes the majority of the network traffic, can be significantly improved.Index Terms¿Extra stage cube; hot spot; interconnection network; multistage interconnection network; parallel processing.
Telecommuting '96 conference report: April 25&ndash;26, 1996; Jacksonville, FL, USA
Authors: Traci A. Carte
Venue: ACM SIGOIS Bulletin (1996)

The term "telecommuting" was first coined by Jack Nilles in 1976, but researcher and practitioner interests in this topic have been inconsistent. In the mid 1980s, considerable telecommuting research was conducted (for example see Olson 1983, DeSanctis 1983) and practitioner interest was high, but by the late eighties and early nineties practitioner interest and research practice waned. If the enthusiasm at Telecommuting '96 is any indication, telecommuting has found renewed popularity. Over 100 practitioners and researchers from 10 different countries converged on Jacksonville, Florida in April to discuss the organizational and technological issues associated with telecommuting adoption and use. Jack Nilles, Tom Davenport and Roy Weber delivered keynote addresses, and the conference sessions included 27 presentations ranging from academic research papers to practitioner panel discussions to best demonstrated practices. The conference proceedings are available on the Web at http://www.cba.uga.edu/tc96/proceedings.html.
Practical verification for requirements model of Hatley/Pirbhai
Authors: Tanehiro Tatsuta
Venue: ACM SIGSOFT Software Engineering Notes (1995)

Five years have passed since translated version of a popular book on Real Time Structured Analysis method was published in Japan. Japanese readers of it have been discussing its practical usage actively. Its research work is however hardly ever presented abroad. We will show here recent Japanese research work on it.
New Encoding/Decoding Methods for Designing Fault-Tolerant Matrix Operations
Authors: D. L. Tao, C. R. P. Hartmann, Yunghsing S. Han
Venue: IEEE Transactions on Parallel and Distributed Systems (1996)

Algorithm-based fault tolerance (ABFT) can provide a low-cost error protection for array processors and multiprocessor systems. Several ABFT techniques (weighted check-sum) have been proposed to design fault-tolerant matrix operations. In these schemes, encoding/decoding uses either multiplications or divisions so that overhead is high. In this paper, new encoding/decoding methods are proposed for designing fault-tolerant matrix operations. The unique feature of these new methods is that only additions and subtractions are used in encoding/decoding. In this paper, new algorithms are proposed to construct error detecting/correcting codes with the minimum Hamming distance 3 and 4. We will show that the overhead introduced due to the incorporation of fault tolerance is drastically reduced by using these new coding schemes.
Integrative assignments for CS1 and CS2 through libraries of abstract data types
Authors: Koldo Gojenola, Tomás A. Pérez, Arturo Jaime
Venue: ACM SIGCSE Bulletin (1995)

As a way to avoid quick student concentration on implementation and computer language issues we have elaborated an integrative set of programming assignments for CS1 and CS2 courses.Our strategy relies on a top-down methodology to develop programming skills and problem-solving capabilities through the use of libraries with high-level Abstract Data Types (ADT). In a first medium-size assignment the novice programmer experiences high-level modular programming, and at a later stage the student is addressed to lower-level programming and data structure concerns.Ada has been used as the programming language, mainly because of its built-in capabilities to use and define reusable libraries of ADTs.Results indicate that this arrangement of assignments successfully reinforces the learning of fundamental concepts such as program design, modularity, testing techniques and increases student satisfaction.
Clock distribution design and verification for PowerPC microprocessors
Authors: Shantanu Ganguly, Shervin Hojat
Venue: Proceedings of the 1995 IEEE/ACM international conference on Computer-aided design (1995)

With the increase of clock speeds, clock skew has become a significant part of the cycle time of high speed microprocessors. While many clocktree routing techniques promise zero or minimal skew, algorithm assumptions or our design methodology constraints often prevent a single approach from being suitable for the entire clock design. In this paper we describe a collection of strategies that are applied at various levels of design to yield clock distribution networks of acceptable skew for the two different clock design styles used by PowerPC processors. We also describe a static timing based approach for analyzing the clock network to detect the various clock violations of interest.
Displacement Structure and Completion Problems
Authors: Tiberiu Constantinescu, Ali H. Sayed, Thomas Kailath
Venue: SIAM Journal on Matrix Analysis and Applications (1995)

A general result is proven concerning time-variant displacement equations with positive solutions in a general operatorial setting. It is then shown that the solutions of several completion problems, recently considered in connection with classical interpolation and moment theory, follow as special cases of the main result. The main purpose of this paper is to show that under supplementary finite-dimensionality conditions, a so-called generalized Schur algorithm, which naturally arises in connection with displacement equations, can be used to prove the above-mentioned result. The associated transmission-line interpretation is also discussed in terms of a cascade of elementary sections with intrinsic blocking properties.
Multimedia coverage of organismal diversity in freshman biology at Clemson University
Authors: Stephen D. Flagg, Robert J. Kosinski
Venue: ACM SIGGRAPH Computer Graphics (1996)

At Clemson University in the fall of 1994, spring of 1995 and the spring of 1996, HyperStudio multimedia modules were used to teach the portion of freshman biology dealing with "diversity" (the different types of animals, plants and microorganisms in the living world). Working individually in our AV center, the students completed the modules outside of class. This experiment saved much class time, and instructional results were positive. This paper discusses this project's methods, problems and results
Object-centered design: a five-phase introduction to object-oriented programming in CS1&ndash;2
Authors: Joel C. Adams
Venue: ACM SIGCSE Bulletin (1996)

With Pascal waning in popularity as the CS1 language of choice, many colleges and universities are considering the adoption of C++ (an imperative and object-oriented hybrid language) as its replacement. An important issue that must be addressed in making such a change is the question of what software design methodology should be taught to CS1 students. Two common answers are (i) continue teaching structured design in CS1 and switch to object-oriented design in CS2; or (ii) teach object-oriented design from the outset in CS1. We believe that both of these approaches have significant drawbacks. To avoid these drawbacks, this paper describes a graduated approach to object-oriented design that we call object-centered design. The approach introduces students to object-oriented design by the end of CS2 without an abrupt paradigm shift, and without requiring an early introduction of inheritance.
Thetis: an ANSI C programming environment designed for introductory use
Authors: Stephen N. Freund, Eric S. Roberts
Venue: ACM SIGCSE Bulletin (1996)

Commercially available compilers, particularly those used for languages like ANSI C that have extensive commercial applicability, are not well-suited to students in introductory computer science courses because they assume a level of sophistication that beginning students do not possess. To alleviate this problem at Stanford, we have developed the Thetis programming environment designed specifically for student use. The system consists of a C interpreter and associated user interface that provides students with simple and easily understood editing, debugging, and visualization capabilities. Reactions of students and instructors indicate that Thetis fulfills the goals we set out to accomplish and provides a significantly better learning environment for students in CS1/CS2.
Context-insensitive alias analysis reconsidered
Authors: Erik Ruf
Venue: Proceedings of the ACM SIGPLAN 1995 conference on Programming language design and implementation (1995)

Recent work on alias analysis in the presence of pointers has concentrated on context-sensitive interprocedural analyses, which treat multiple calls to a single procedure independently rather than constructing a single approximation to a procedure's effect on all of its callers. While context-sensitive modeling offers the potential for greater precision by considering only realizable call-return paths, its empirical benefits have yet to be measured.This paper compares the precision of a simple, efficient, context-insensitive points-to analysis for the C programming language with that of a maximally context-sensitive version of the same analysis. We demonstrate that, for a number of pointer-intensive benchmark programs, context-insensitivity exerts little to no precision penalty. We also describe techniques for using the output of context-insensitive analysis to improve the efficiency of context-sensitive analysis without affecting precision.
Forward Stability and Transmission of Shifts in the $QR$ Algorithm
Authors: David S. Watkins
Venue: SIAM Journal on Matrix Analysis and Applications (1995)

The $QR$ algorithm is one of the most popular methods for calculating the eigenvalues of a matrix. In the course of iterations of the implicitly shifted $QR$ algorithm on an upper Hessenberg matrix, it is crucial to check for zeros on the subdiagonal of the matrix. A zero on the subdiagonal allows the problem to be split into two independent subproblems. Moreover, if the splitting is not carried out, the subdiagonal zero will cause the subsequent $QR$ iterations to break down. In practice exact zeros are rare; instead one normally sees very tiny numbers like $10^{-19}$. It is reasonable to set such numbers to zero and split the problem. Indeed it is widely believed that it is crucial to carry out a splitting in such cases. Although such small entries, if left in place, will not cause the $QR$ iterations to break down outright, they will (or so it is thought) trigger a breakdown of forward stability; small roundoff errors will be magnified dangerously, and the $QR$ step will degenerate to a random similarity transformation. The first objective of this paper is to show that this widespread belief is mistaken; tiny subdiagonal entries do not normally cause forward instability or interfere in any way with the convergence of the algorithm. The second objective is to show that even in situations where forward instability does occur, the $QR$ step is not normally rendered ineffective. On the contrary, the shift is transmitted accurately through the region of instability in such a way that a $QR$ step with the chosen shift is performed on the trailing submatrix.
Multi-table joins through bitmapped join indices
Authors: Patrick O'Neil, Goetz Graefe
Venue: ACM SIGMOD Record (1995)

This technical note shows how to combine some well-known techniques to create a method that will efficiently execute common multi-table joins. We concentrate on a commonly occurring type of join known as a star-join, although the method presented will generalize to any type of multi-table join. A star-join consists of a central detail table with large cardinality, such as an orders table (where an order row contains a single purchase) with foreign keys that join to descriptive tables, such as customers, products, and (sales) agents. The method presented in this note uses join indices with compressed bitmap representations, which allow predicates restricting columns of descriptive tables to determine an answer set (or foundset) in the central detail table; the method uses different predicates on different descriptive tables in combination to restrict the detail table through compressed bitmap representations of join indices, and easily completes the join of the fully restricted detail table rows back to the descriptive tables. We outline realistic examples where the combination of these techniques yields substantial performance improvements over alternative, more traditional query evaluation plans.
The $H_/infty$-Problem for Infinite-Dimensional Semilinear Systems
Authors: Viorel Barbu
Venue: SIAM Journal on Control and Optimization (1995)

We study the $H_\infty$-optimal control problem for semilinear systems in Hilbert spaces in connection with the corresponding $H_\infty$-problem for the linearized system around an equilibrium state. The result of this paper, which expands some recent results of A. J. van der Schaft, is that if the linearized $H_infty$-problem has a suboptimal solution, then a suboptimal solution to the $H_infty$-problem for the semilinear system can be constructed in terms of a Hamilton-Jacobi equation.
Authentication protocols for personal communication systems
Authors: Hung-Yu Lin, Lein Harn
Venue: ACM SIGCOMM Computer Communication Review (1995)

Masquerading and eavesdropping are major threats to the security of wireless communications. To provide proper protection for the communication of the wireless link, contents of the communication should be enciphered and mutual authentication should be conducted between the subscriber and the serving network. Several protocols have been proposed by standards bodies and independent researchers in recent years to counteract these threats. However, the strength of these protocols is usually weakened in the roaming environment where the security breach of a visited network could lead to persistent damages to subscribers who visit. The subscriber's identity is not well protected in most protocols, and appropriate mechanisms solving disputes on roaming bills are not supported either. To solve these problems, new authentication protocols are proposed in this paper with new security features that have not been fully explored before.
Structure and chance: melding logic and probability for software debugging
Authors: Lisa Burnell, Eric Horvitz
Venue: Communications of the ACM (1995)

Software errors abound in the world of computing. Sophisticated computer programs rank high on the list of the most complex systems ever created by humankind. The complexity of a program or a set of interacting programs makes it extremely difficult to perform offline verification of run-time behavior. Thus, the creation and maintenance of program code is often linked to a process of incremental refinement and ongoing detection and correction of errors. To be sure, the detection and repair of program errors is an inescapable part of the process of software development. However, run-time software errors may be discovered in fielded applications days, months, or even years after the software was last modified&mdash;especially in applications composed of a plethora of separate programs created and updated by different people at different times. In such complex applications, software errors are revealed through the run-time interaction of hundreds of distinct processes competing for limited memory and CPU resources. Software developers and support engineers responsible for correcting software problems face difficult challenges in tracking down the source of run-time errors in complex applications. The information made available to engineers about the nature of a failure often leaves open a wide range of possibilities that must be sifted through carefully in searching for an underlying error.
The diverse career orientations of MIS personnel
Authors: James J. Jiang, Gary Klein, Joseph Balloun
Venue: ACM SIGCPR Computer Personnel (1995)

Past studies have found different dominant career anchors present among information system (IS) personnel. This study provides additional evidence that IS personnel have a diversity of career orientations and that the orientations can vary according to external conditions. A survey of IS personnel supports the premise that each professional situation and each individual is unique. Organizations are better off creating flexible career structures rather than rigid career paths and must be prepared to adjust to changes in the environment.
On the complementarity of workflow management and business process modeling
Authors: Stefan Jablonski
Venue: ACM SIGOIS Bulletin (1995)

The way business processes are implemented currently is out-of-date. It cannot keep pace with the rapid changes of today's business behavior. Thus, new ways to structure business processes have to be investigated. Business process reengineering is the upcoming discipline that is able to cope with the requirements posted by today's way of conducting business. However, models of business processes defined through business process reengineering still lack a suitable execution environment. Conventional infrastructures are too static and inflexible to adequately reflect rapid changes in business processes. Workflow management promises to cope with this requirement by providing a highly dynamic execution platform for multi-faceted business processes. In this research paper we discuss the interrelationship between business process modeling and workflow management and show how they can mutually benefit from each other.