ppxscal/embedding_network huggingface dataset:
Bifocal sampling for skew-resistant join size estimation
Authors: Sumit Ganguly, Phillip B. Gibbons, Yossi Matias, Avi Silberschatz
Venue: ACM SIGMOD Record (1996)

This paper introduces bifocal sampling, a new technique for estimating the size of an equi-join of two relations. Bifocal sampling classifies tuples in each relation into two groups, sparse and dense, based on the number of tuples with the same join value. Distinct estimation procedures are employed that focus on various combinations for joining tuples (e.g., for estimating the number of joining tuples that are dense in both relations). This combination of estimation procedures overcomes some well-known problems in previous schemes, enabling good estimates with no a priori knowledge about the data distribution. The estimate obtained by the bifocal sampling algorithm is proven to lie with high probability within a small constant factor of the actual join size, regardless of the skew, as long as the join size is Omega;(n lg n), for relations consisting of n tuples. The algorithm requires a sample of size at most O( radic;n lg n). By contrast, previous algorithms using a sample of similar size may require the join size to be Omega;(n radic;n) to guarantee an accurate estimate. Experimental results support the theoretical claims and show that bifocal sampling is practical and effective.
Power analysis and low-power scheduling techniques for embedded DSP software
Authors: Mike Tien-Chien Lee, Vivek Tiwari, Sharad Malik, Masahiro Fujita
Venue: Proceedings of the 8th international symposium on System synthesis (1995)

Abstract: This paper describes the application of a measurement based power analysis technique for an embedded DSP processor. An instruction-level power model for the processor has been developed using this technique. Significant points of difference have been observed between this model and the ones developed earlier for some general-purpose commercial microprocessors. In particular, the effect of circuit state on the power cost of an instruction stream is more marked in the case of this DSP processor. In addition, the DSP processor has a special architectural feature that allows instructions to be packed into pairs. The energy reduction possible through the use of this feature is studied. The on-chip Booth multiplier on the processor is a major source of energy consumption for DSP programs. A micro-architectural power model for the multiplier is developed and analyzed for further energy minimization. A scheduling algorithm incorporating these new techniques is proposed to reduce the energy consumed by DSP software. Energy reductions varying from 11% to 56% have been observed for several example programs. These energy savings are real and have been verified through physical measurement.
Combining analyses, combining optimizations
Authors: Cliff Click, Keith D. Cooper
Venue: ACM Transactions on Programming Languages and Systems (TOPLAS) (1995)

Modern optimizing compilers use several passes over a program's intermediate representation to generate good code. Many of these optimizations exhibit a phase-ordering problem. Getting the best code may require iterating optimizations until a fixed point is reached. Combining these phases can lead to the discovery of more facts about the program, exposing more opportunities for optimization. This article presents a framework for describing optimizations. It shows how to combine two such frameworks and how to reason about the properties of the resulting framework. The structure of the frame work provides insight into when a combination yields better results. To make the ideas more concrete, this article presents a framework for combining constant propagation, value numbering, and unreachable-code elimination. It is an open question as to what other frameworks can be combined in this way.
Development of a generic SIMNET II simulation package for unidirectional, sideloading AGV systems
Authors: Roger McHaney
Venue: Proceedings of the 27th conference on Winter simulation (1995)

The use of simulation in the design stages of complex materials handling systems has become increasingly prevalent in recent years. Computer simulation has become so important to manufacturing system designs that Pritsker (1992) calls simulation "the premier technique of industrial engineering". It is upon this foundation the project described in this paper has been constructed. This project describes the development of a generic simulation which can be used to model unidirectional, sideloading automatic guided vehicle (AGV) systems. Guidepath, programming logic and queuing logic are all represented through databases. New systems can be input only through changes to the database. The simulation system was developed using the SIMNET II modeling language (Taha 1988, 1992). An implementation example is also provided.
WorkFlow systems: a few definitions and a few suggestions
Authors: Paulo Barthelmess, Jacques Wainer
Venue: Proceedings of conference on Organizational computing systems (1995)

This paper hopes to make a contribution on three aspects of workflow systems: we stress the fact that there is a broken symetry between the level of the specification of the procedures and the level of their enactment; we propose some ways of classifying activities and exceptions; and we propose some run-time functionalities to help users deal with exceptions.
Knowledge-based OOP
Authors: Ka-Wing Wong
Venue: ACM SIGICE Bulletin (1996)

Writing concurrent programs in the Object-Oriented Programming (OOP) environment is a challenge. In this paper, we present a knowledge-based solution in which program properties are specifiable and verifiable. We demonstrate the usefulness of the solution by solving the mutual exclusion problem [4] for a set of processes competing for a method in a class.
Inverse pairs of test matrices
Authors: Wilhelm S. Ericksen
Venue: ACM Transactions on Mathematical Software (TOMS) (1985)

Algorithms that are readily programmable are provided for constructing inverse pairs of matrices with elements in a field, a division ring, or a ring.
Adapting materialized views after redefinitions
Authors: Ashish Gupta, Inderpal S. Mumick, Kenneth A. Ross
Venue: Proceedings of the 1995 ACM SIGMOD international conference on Management of data (1995)

We consider a variant of the view maintenance problem: How does one keep a materialized view up-to-date when the view definition itself changes? Can one do better than recomputing the view from the base relations? Traditional view maintenance tries to maintain the materialized view in response to modifications to the base relations; we try to "adapt" the view in response to changes in the view definition.Such techniques are needed for applications where the user can change queries dynamically and see the changes in the results fast. Data archaeology, data visualization, and dynamic queries are examples of such applications.We consider all possible redefinitions of SQL SELECT-FROM-WHERE-GROUPBY, UNION, and EXCEPT views, and show how these views can be adapted using the old materialization for the cases where it is possible to do so. We identify extra information that can be kept with a materialization to facilitate redefinition. Multiple simultaneous changes to a view can be handled without necessarily materializing intermediate results. We identify guidelines for users and database administrators that can be used to facilitate efficient view adaptation.
The Global Control of Nonlinear Diffusion Equations
Authors: J. E. Rubio
Venue: SIAM Journal on Control and Optimization (1995)

The boundary control of a nonlinear difussion equation with an integral performance criterion and a fixed final state is considered. By means of a process of embedding used by the author and others for finite- dimensional systems, this problem is replaced by one in which a linear form is minimized over a set of pairs of positive measures satisfying linear constraints. The advantages of this formulation are: (i) There is an automatic existence theory. (ii) There exists the possibility of using linear functional analysis to develop the theory. (iii) The minimization is global. The final state is only reached, however, in an asymptotic fashion, as the number of constraints being considered tends to infinity. A theory of controllability and reachability is developed, as well as a computational method using an infinite-dimensional simplex method. An example is given.
Workshop summary: report on the workshop on &ldquo;collaborative realtime process management&rdquo; at CSCW'94
Authors: Yvonne Wærn, Patricia Jones
Venue: ACM SIGOIS Bulletin (1995)

Several situations in modern working life imply that people have to cooperate in order to handle dynamic systems. The work is distributed in several respects; people work with different tasks and have different expertise, they are often geographically distributed and they work at different times or cover different time scales. The activities are often time critical and cooperation has to be efficient. The problems involved in these situations have great economical and societal impacts. Approaches to the problems require expertise in several domains.The objectives of the workshop was to identify key features of collaborative process management and to identify critical needs in the domain of collaborative process management.
The benefits of clustering in shared address space multiprocessors: an applications-driven investigation
Authors: Andrew Erlichson, Basem A. Nayfeh, Jaswinder P. Singh, Kunle Olukotun
Venue: Proceedings of the 1995 ACM/IEEE conference on Supercomputing (CDROM) (1995)

Clustering processors together at a level of the memory hierarchy in shared address space multiprocessors appears to be an attractive technique from several standpoints: Resources are shared, packaging technologies are exploited, and processors within a cluster can share data more effectively. We investigate the performance benefits that can be obtained by clustering on a range of important scientific and engineering applications in moderate to large scale cache coherent machines with small degrees of clustering (up to one eighth of the total number of processors in a cluster). We find that except for applications with near neighbor communication topologies this degree of clustering is not very effective in reducing the inherent communication to computation ratios. Clustering is more useful in reducing the the number of remote capacity misses in unstructured applications, and can improve performance substantially when small first-level caches are clustered in these cases. This suggests that clustering at the first level cache might be useful in highly-integrated, relatively fine-grained environments. For less integrated machines such as current distributed shared memory multiprocessors, our results suggest that clustering at the first-level caches is not very useful in improving application performance; however our results also suggest that in an machine with long interprocessor communication latencies, clustering further away from the processor can provide performance benefits.
Military force structure and realignment: &ldquo;sharpening the edge&rdquo; through dynamic simulation
Authors: Stephen R. Parker
Venue: Proceedings of the 27th conference on Winter simulation (1995)

A unique approach is developed for analyzing force structures of the armed forces of the United States. With this approach new ways of measuring combat readiness are available to ensure that the armed forces remain ready to fight during the defense drawdown of the 1990s. As part of the approach, a symbolic network representative language was developed which combines the continuous variable features of system dynamics and the discrete event features of conventional simulation techniques. This network representative language, referred to as Dynamic Simulation (DYNASIM), is built to integrate with the network SLAMSYSTEM environment. The contribution of this research is a prescribed method for the strategic analyst to develop an influence diagram which can be used to analyze force structures within the combat logistics domain. DYNASIM's format structure enables the user to focus attention on the development of the model, rather than the computational aspects of simulation.
Database security in a client/server environment
Authors: Carl Stephen Guynes, Robert M. Golladay, Richard A. Huff
Venue: ACM SIGSAC Review (1996)

Important database security issues arise from the increasing number of users having various levels of access to both central and distributed databases. This article addresses some of the security issues and security measures necessary for database access controls to be effective in a client/server environment. This paper also examines the problems associated with enforcing stated DBMS access controls, and how the data administration team can work with top management to ensure that the current database security strategy is consistent with the goals of the organization. Although early security techniques utilized an approach of simply limiting access to corporate data, today's demands for data availability have created a new subset of related security issues.
Locating nearby copies of replicated Internet servers
Authors: James D. Guyton, Michael F. Schwartz
Venue: Proceedings of the conference on Applications, technologies, architectures, and protocols for computer communication (1995)

In this paper we consider the problem of choosing among a collection of replicated servers, focusing on the question of how to make choices that segregate client/server traffic according to network topology. We explore the cost and effectiveness of a variety of approaches, ranging from those requiring routing layer support (e.g., anycast) to those that build location databases using application-level probe tools like traceroute. We uncover a number of tradeoffs between effectiveness, network cost, ease of deployment, and portability across different types of networks. We performed our experiments using a simulation parameterized by a topology collected from 7 survey sites across the United States, exploring a global collection of Network Time Protocol servers.
New horizons in commercial and industrial AI
Authors: Toshinori Munakata
Venue: Communications of the ACM (1995)

AI as a field has undergone rapid growth in diversification and practicality. For the past 10 years, the repertoire of AI techniques has evolved and expanded. Scores of newer fields have recently been added to the traditional domains of practical AI. Although much practical AI is still best characterized as advanced computing rather than intelligence, applications in everyday commercial and industrial settings have certainly increased, especially since 1990. Additionally, AI has shown a growing influence on other computer science areas, such as databases, software engineering, distributed computing, computer graphics, user interfaces, and stimulation.
A 3D sketching tool: an MA computing in design research project
Authors: Helen Poletti
Venue: ACM SIGGRAPH Computer Graphics (1995)

For centuries, the use of a sketch book as an experimental space and as a spontaneous, reference resource has been widespread amongst artists and designers. This is evident from the wealth of ideas expressed in the notebooks of Leonardo da Vinci [1] and in the accounts of Delacroix who was said to have loosened up his hand by drawing from the imagination, producing a variety of sketches that provided him with ideas to be used at a later date.By sketching, a designer releases a fluid stream of visual experiences, not all of which can mentally be retained. However, single sketches give only single view point representations of objects. It is therefore necessary to translate " hellip;the back of-the-envelope stuff hellip;" [2] into a three dimensional scaled model in order to fully realize a form. Much creativity and enthusiasm is dissipated during this transformation. Similarly, the precise preparation needed for input to a standard CAD system for a computer generated models is not consistent with the excitement of creative exploration expressed by Henry Moore. "The act of converting an idea into line and other marks on paper often excites the mind and frees the imagination encouraging the flow of creative thought." [2]The desire to observe and create directly in a 3D space, capturing the essence of the sketch and receiving instantaneous three dimensional feedback, has inspired the development of this project.
Introducing computer concepts by simulating a simple computer
Authors: Robert A. Campbell
Venue: ACM SIGCSE Bulletin (1996)

The simulated computer consists of (1) main memory, (2) a register known as the accumulator, (3) a central processing unit (CPU), and (4) an instruction counter. This computer recognizes 8 op codes (Halt, Load, Store, Add, Subtract, Read, Write, and Branch On Zero). The computer is simulated by creating a program in Pascal or C++. This program simulates the execution of programs written by students, such as adding two numbers and printing their sum. Student programs are written in machine language and executed by the simulated computer. Students can write programs in assembly language, compile them by hand, and then test them by running them on the simulated computer. This example has been helpful in teaching students what a computer is and what computers can do.
Collaborations within higher education
Authors: Jennifer Fajman
Venue: ACM SIGUCCS Newsletter (1995)

One of the challenges for academic information technology service organizations is finding ways to effectively integrate technology into the learning process. There are a number of approaches that can be used; one that is successful at the University of Maryland at College Park is collaboration with academic departments. These collaborations form alliances and bring together academic scholars with information technology providers. Together, academicians and information technology providers, can enhance the learning process. Following are some examples of collaborations that have worked well at the University of Maryland.
Lyapunov-Like Techniques for Stochastic Stability
Authors: Patrick Florchinger
Venue: SIAM Journal on Control and Optimization (1995)

The purpose of this paper is to study the stabilizability problem for control stochastic nonlinear systems driven by a Wiener process. Sufficient conditions for the existence of stabilizing feedback laws that are smooth, except possibly at the equilibrium point of the system, are provided by means of stochastic Lyapunov-like techniques. The notion of dynamic asymptotic stability in probability of control stochastic differential systems is introduced and the stabilization by means of dynamic controllers is studied.
Efficient maintenance of materialized mediated views
Authors: James J. Lu, Guido Moerkotte, Joachim Schue, V. S. Subrahmanian
Venue: Proceedings of the 1995 ACM SIGMOD international conference on Management of data (1995)

Integrating data and knowledge from multiple heterogeneous sources -- like databases, knowledge bases or specific software packages -- is often required for answering certain queries. Recently, a powerful framework for defining mediated views spanning multiple knowledge bases by a set of constrained rules was proposed [24, 4, 16]. We investigate the materialization of these views by unfolding the view definition and the efficient maintenance of the resulting materialized mediated view in case of updates. Thereby, we consider two kinds of updates: updates to the view and updates to the underlying sources. For each of these two cases several efficient algorithms maintaining materialized mediated views are given. We improve on previous algorithms like the DRed algorithm [12] and introduce a new fixpoint operator WP which -- opposed to the standard fixpoint operator TP [9] -- allows us to correctly capture the update's semantics without any recomputation of the materialized view.
DASD dancing: a disk load balancing optimization scheme for video-on-demand computer systems
Authors: Joel L. Wolf, Philip S. Yu, Hadas Shachnai
Venue: Proceedings of the 1995 ACM SIGMETRICS joint international conference on Measurement and modeling of computer systems (1995)

For a video-on-demand computer system we propose a scheme which balances the load on the disks, thereby helping to solve a performance problem crucial to achieving maximal video throughput. Our load balancing scheme consists of two stages. The static stage determines good assignments of videos to groups of striped disks. The dynamic phase uses these assignments, and features a DASD dancing algorithm which performs real-time disk scheduling in an effective manner. Our scheme works synergistically with disk striping. We examine the performance of the DASD dancing algorithm via simulation experiments.
Object-oriented AI: a commercial perspective
Authors: Paul Harmon
Venue: Communications of the ACM (1995)

Computer journals and magazines are currently filled with stories about object technology, just as they were filled with stories about artificial intelligence (AI) and expert systems in the early 1980s. The naive reader might think that expert systems technology had failed and that object-oriented technology was the hot new software approach of the 1990s.
Taming Xunet III
Authors: Nikos G. Aneroussis, Aurel A. Lazar, Dimitrios E. Pendarakis
Venue: ACM SIGCOMM Computer Communication Review (1995)

An architecture for network management and control for emerging wide-area ATM networks is presented. The architecture was implemented on XUNET III, a nationwide ATM network deployed by AT amp;T. The Xunet network management system is based on the OSI standards and includes configuration, fault and performance management. An OSI agent resides at every switching node. Its capabilities include monitoring of cell level quality of service in real time and estimation of the schedulable region. The complexity and accuracy of real-time monitoring functionalities is investigated. To provide realistic traffic loads, distributed traffic generation systems both at the cell and call level have been implemented. In order to study the trade-off between the network transport and signalling system we have implemented a virtual path signalling capability. Our experiments show that the ability of a network to admit calls is limited by two distinct factors: the capacity of the network and the processing power of the signalling system. Depending on the bandwidth requirement of calls, the limit of one or the other will be first reached. This is a key observation, unique to broadband networks.
Amplitude selection in transient sensitivity analysis
Authors: Douglas J. Morrice, Sheldon H. Jacobson
Venue: Proceedings of the 27th conference on Winter simulation (1995)

Most research in computer simulation sensitivity analysis can be classified as steady-state sensitivity analysis. This paper considers an approach to transient sensitivity analysis, i.e. an approach to study the transient behaviour of a performance measure in response to changes in one or more input factors. We examine the issue of factor magnitude change (or factor amplitude) selection and how the choice of factor amplitudes impacts the overall analysis. We also consider a control variate variance reduction scheme designed to improve performance when small amplitude changes are used. A tandem queue example illustrates the results.