ppxscal/embedding_network huggingface dataset:
Incremental computation of nested relational query expressions
Authors: Lars Baekgaard, Leo Mark
Venue: ACM Transactions on Database Systems (TODS) (1995)

Efficient algorithms for incrementally computing nested query expressions do not exist. Nested query expressions are query expressions in which selection/join predicates contain subqueries. In order to respond to this problem, we propose a two-step strategy for incrementaly computing nested query expressions. In step (1), the query expression is transformed into an equivalent unnested flat query expression. In step (2), the flat query expression is incrementally computed. To support step (1), we have developed a very concise algebra-to-algebra transformation algorithm, and we have formally proved its correctness. The flat query expressions resulting from the transformation make intensive use of the relational set-difference operator. To support step (2), we present and analyze an efficient algorithm for incrementally computing set differences based on view pointer caches. When combined with existing incremental algorithms for SPJ queries, our incremental set-difference algorithm can be used to compute the unnested flat query expressions efficiently. It is important to notice that without our incremental set-difference algorithm the existing incremental algorithms for SPJ queries are useless for any query involving the set-difference operator, including queries that are not the result of unnesting nested queries.
Online tracking of mobile users
Authors: Baruch Awerbuch, David Peleg
Venue: Journal of the ACM (JACM) (1995)

This paper deals with the problem of maintaining a distributed directory server, that enables us to keep track of mobile users in a distributed network. The paper introduces the graph-theoretic concept of regional matching, and demonstrates how finding a regional matching with certain parameters enables efficient tracking. The communication overhead of our tracking mechanism is within a polylogarithmic factor of the lower bound.
Implementation and performance of integrated application-controlled file caching, prefetching, and disk scheduling
Authors: Pei Cao, Edward W. Felten, Anna R. Karlin, Kai Li
Venue: ACM Transactions on Computer Systems (TOCS) (1996)

As the performance gap between disks and micropocessors continues to increase, effective utilization of the file cache becomes increasingly immportant. Application-controlled file caching and prefetching can apply application-specific knowledge to improve file cache management. However, supporting application-controlled file caching and prefetching is nontrivial because caching and prefetching need to be integrated carefully, and the kernel needs to allocate cache blocks among processes appropriately. This article presents the design, implementation, and performance of a file system that integrates application-controlled caching, prefetching, and disk scheduling. We use a two-level cache management strategy. The kernel uses the LRU-SP (Least-Recently-Used with Swapping and Placeholders) policy to allocate blocks to processes, and each process integrates application-specific caching and prefetching based on the controlled-aggressive policy, an algorithm previously shown in a theoretical sense to be nearly optimal. Each process also improves its disk access latency by submittint its prefetches in batches so that the requests can be scheduled to optimize disk access performance. Our measurements show that this combination of techniques greatly improves the performance of the file system. We measured that the running time is reduced by 3% to 49% (average 26%) for single-process workloads and by 5% to 76% (average 32%) for multiprocess workloads.
Support-Vector Networks
Authors: Corinna Cortes, Vladimir Vapnik
Venue: Machine Learning (1995)

The support-vector network is a new learning machine for two-group classification problems. The machine conceptually implements the following idea: input vectors are non-linearly mapped to a very high-dimension feature space. In this feature space a linear decision surface is constructed. Special properties of the decision surface ensures high generalization ability of the learning machine. The idea behind the support-vector network was previously implemented for the restricted case where the training data can be separated without errors. We here extend this result to non-separable training data.High generalization ability of support-vector networks utilizing polynomial input transformations is demonstrated. We also compare the performance of the support-vector network to various classical learning algorithms that all took part in a benchmark study of Optical Character Recognition.
Existence of EMS Solutions and a Priori Estimates
Authors: Geoff A. Latham
Venue: SIAM Journal on Matrix Analysis and Applications (1995)

Solvability of the nonlinear EMS (estimate, maximize, smooth) equations in the nonnegative quadrant is established by the use of the Brouwer fixed point theorem and a priori estimates from Perron--Frobenius theory. Existence of solutions and of an a priori estimate are also proven for a generalization of the EMS equations. The a priori estimates illustrate the quantification shortcomings of the EMS algorithm and should be carefully considered both before applying the algorithm and in the choice of smoothing.
Minimization of Memory and Network Contention for Accessing Arbitrary Data Patterns in SIMD Systems
Authors: Mayez A. Al-Mouhamed, Steven S. Seiden
Venue: IEEE Transactions on Computers (1996)

Finding general XOR-schemes to minimize memory and network contention for accessing arrays with arbitrary sets of data templates is presented. A combined XOR-matrix is proposed together with a necessary and sufficient condition for conflict-free access. We present a new characterization of the baseline network. Finding an XOR-matrix for combined templates is shown to be an NP-complete problem. A heuristic is proposed for finding XOR-matrices by determining the constraints of each template-matrix and solving a set of simultaneous equations for each row. Evaluation shows significant reduction of memory and network contention compared to interleaving and to static row-column-diagonals storage.
Simulation environment for electronics manufacturing
Authors: Phillip A. Farrington, John S. Rogers, Bernard J. Schroer, James J. Swain, John L. Evans
Venue: Proceedings of the 27th conference on Winter simulation (1995)

This paper presents the development of an environment to simplify the creation of simulation models for high-volume electronics manufacturing systems. The simulation environment consists of a problem definer, a static analyzer and a code generator. Included in this paper is an overview of the environment, an application of the system at Chrysler Electronics, and a discussion of system advantages.
Optimal Supervisory Control of Discrete Event DynamicalSystems
Authors: Ratnesh Kumar, Vijay K. Garg
Venue: SIAM Journal on Control and Optimization (1995)

The notion of optimal supervisory control of discrete event dynamical systems (DEDSs) is formalized in the framework of Ramadge and Wonham. A DEDS is modeled as a state machine and is controlled by disabling some of its transitions. Two types of cost functions are defined: a cost of control function corresponding to disabling transitions in the state machine, and a penalty of control function corresponding to reaching some undesired states or not reaching some desired states in the controlled system. The control objective is to design an optimal control mechanism, if it exists, so that the net cost is minimized. Since a DEDS is represented as a state machine---a directed graph---network flow techniques are naturally applied for designing optimal supervisors. It is also shown that our techniques can be used to solve supervisory control problems under complete as well as partial observation. In particular, for the first time, techniques for computing the supremal controllable and normal sublanguage and the infimal controllable and normal/observable superlanguage without having to perform alternate computations of controllable and normal/observable languages are obtained.
C in the first course considered harmful
Authors: L. F. Johnson
Venue: Communications of the ACM (1995)

To advice or not to advise, that is the dilemma. To be or not to be, that is the question. To see or not to see, that is the difficulty.
The new middleware
Authors: Rich Finkelstein
Venue: ACM SIGMOD Record (1995)

USING MIDDLEWARE, CUSTOMERS CAN DEPLOY COST-EFFECTIVE AND HIGHLY FUNCTIONAL CLIENT/SERVER APPLICATIONS &mdash; ONCE THEY WORK OUT THE KINKS.
Workshop on mobile computing systems and applications, December 1994: digest of proceedings
Authors: M. Satyanarayanan
Venue: ACM SIGOPS Operating Systems Review (1995)

The goal of this two-day meeting was to foster interaction between active workers in mobile computing, with a view toward cross-fertilization of ideas. Given the youth of the field, such interactions could have substantial impact on its future direction. In keeping with this goal, the conference organizers chose to have a small, informal workshop rather than a larger and more formal conference. The workshop was sponsored by the IEEE Computer Society Technical Committee on Operating Systems, in cooperation with ACM SIGOPS and USENIX.The workshop was held on Thursday and Friday December 8-9 1994 at the Dream Inn in Santa Cruz. The weather was beautiful and the oceanside locale spectacular --- alas, it is not clear whether these helped or hindered the workshop, since many longing looks were evident on the faces of participants as they gazed out of the windows! The General Chair, Darrell Long, had done an excellent job of selecting the workshop site and setting the stage for the workshop. He was assisted in local arrangements by two student volunteers, Jim Cummiskey and Chane Fullmer.What follows is a summary of the discussions that took place during the workshop. It is based on notes taken by four student volunteers (Peter Grillo, C.K. Toh, Adrian Friday, and N. Asokan). They did an excellent job of taking detailed and complete notes. Any errors or omissions in this document are certainly my responsibility, not theirs.This digest is intended to be a supplement to the papers in the proceedings, not a substitute. Rather than producing a verbatim transcript, I've tried to focus on those interactions that seemed most insightful, controversial or evoked most response from the audience. Such a report must, by its very nature, be subjective. I've tried to be as objective as possible, but I'm sure there are places where my personal biases show through. My apologies in advance if you attended the workshop and your favorite comment, question or discussion isn't mentioned here.
Extending temporal logic to support high-level simulations
Authors: Alexander Tuzhilin
Venue: ACM Transactions on Modeling and Computer Simulation (TOMACS) (1995)

A high-level simulation language based on temporal logic is described. The language combines a large set of temporal tenses and a rich class of high-level modeling primitives. Also an implementation of the language interpreter is presented. Finally, a real-world case study is described that shows how a programmer can develop structured, reliable, and well-maintainable simulation programs using the language.
Model Uncertainty in Discrete Event Systems
Authors: Stanley Young, Vijay K. Garg
Venue: SIAM Journal on Control and Optimization (1995)

Earlier work concerning control of discrete event systems usually assumed that a correct model of the system to be controlled was available. A goal of this work is to provide an algorithm for determining the correct model from a set of models. The result of the algorithm is a finite language that can be used to test for the correct model or notification that the remaining models cannot be controllably distinguished. We use the finite state machine model with controllable and uncontrollable events presented by Ramadge and Wonham.
DISplay: a system for visual-interaction in distributed simulations
Authors: Edward Mascarenhas, Vernon Rego, Janche Sang
Venue: Proceedings of the 27th conference on Winter simulation (1995)

We propose an application-independent visual interaction library (VIL) well suited to distributed simulation. Advantages of this system include ease of use, flexibility, code reuse, and modularity. Our design ideas are manifest, in the DISplay system, a graphical user-interaction and display library which binds to any parallel software system. We provide examples of its interactive use in the the dynamic display of results from sequential queueing simulations, and distributed particle-physics simulations. These examples illustrate synchronization of multiple remote display requests and potential for enhanced parallel simulation. Also presented are provisions for customized user-interaction dialogs-for application-related input, and bi-directional interaction-between user and application.
A Preconditioner Based on Domain Decomposition for H-P Finite-Element Approximation on Quasi-Uniform Meshes
Authors: Mark Ainsworth
Venue: SIAM Journal on Numerical Analysis (1996)

The problem of solving the algebraic systems arising from the discretization of a symmetric, elliptic boundary value problem using $h$-$p$ finite-element methods in two dimensions is addressed. A preconditioning technique similar to those of Bramble, Pasciak, and Schatz [Math. Comp., 47 (1986), pp. 103--135] based on domain decomposition (also known as substructuring) is developed. The method is applicable to problems on general domains involving differential operators with quite general coefficients. The algorithm reduces to that of Bramble, Pasciak, and Schatz if linear elements are used. It is shown that the condition number of the preconditioned system (which determines the rate of convergence of the iterative method) grows at most as $(1 + \log^2 p)\,(1+\log^2 (Hp/h))$, where $p$ is the polynomial degree, $h$ is the size of the elements, and $H$ is the size of the subdomains.
Efficient algorithms for atmospheric correction of remotely sensed data
Authors: Hassan Fallah-Adl, Joseph JáJá, Shunlin Liang, Yoram J. Kaufman, John Townshend
Venue: Proceedings of the 1995 ACM/IEEE conference on Supercomputing (CDROM) (1995)

Remotely sensed imagery has been used for developing and validating various studies regarding land cover dynamics. However, the large amounts of imagery collected by the satellites are largely contaminated by the effects of atmospheric particles. The objective of atmospheric correction is to retrieve the surface reflectance from remotely sensed imagery by removing the atmospheric effects. We introduce a number of computational techniques that lead to a substantial speedup of an atmospheric correction algorithm based on using look-up tables. Excluding I/O time, the previous known implementation processes one pixel at a time and requires about 2.63 seconds per pixel on a SPARC-10 machine, while our implementation is based on processing the whole image and takes about 4-20 microseconds per pixel on the same machine. We also develop a parallel version of our algorithm that is scalable in terms of both computation and I/O. Experimental results obtained show that a Thematic Mapper (TM) image (36 MB per band, 5 bands need to be corrected) can be handled in less than 4.3 minutes on a 32-node CM-5 machine, including I/O time.
Surfin on the Net
Authors: Christopher McKenna
Venue: ACM SIGICE Bulletin (1995)

Not too long ago the internet was an imagery land of ftp sites and gopher servers scattered across the world with no convenient pathway to where anything was. You heard about an ftp or gopher server from a friend or stumbled upon it by accident. Maybe you were impressed to get a piece of mail from a friend in another state or country in seconds after he/she sent it. Maybe you even followed a world wide forum on your favorite topic or application. In this vast land of information, however, nothing was there to tie these services together. Just like everything else in the world, the internet got better and gained another TCP/IP client server tool, the World Wide Web (WWW). A spider net of documents containing images, sounds, binaries, and even movie clips. The internet finally had some backbone and shape to it. It was like a new way of living had emerged over night, I do mean overnight.
Leveraging the information asset
Authors: Janet Perna
Venue: Proceedings of the 1995 ACM SIGMOD international conference on Management of data (1995)

Data is a corporate asset, and being able to derive more information from data can provide database users with a competitive advantage. For example, catching on to trends quickly can reduce unwanted store inventory and lower capital outlay for the same profit. If you have store sales data by product analyzed on a daily basis, that can make a 2-3% difference in margin -- and in a business where margins might be 4%, this is a significant competitive edge. This paper will cover what technology is needed by customers to leverage their information assets. Real-time access to production point of sale information, database mining for analysis to detect trends immediately, high performance, and multi-vendor database connectivity, cooperation among heterogeneous clients and servers are among the customer needs we are seeing in the marketplace.
The graphical benchmark information service
Authors: Mark Papiani, Anthony J. G. Hey, Roger W. Hockney
Venue: Scientific Programming (1995)

Unlike single-processor benchmarks, multiprocessor benchmarks can yield tens of numbers for each benchmark on each computer, as factors such as the number of processors and problem size are varied. A graphical display of performance surfaces therefore provides a satisfactory way of comparing results. The University of Southampton has developed the Graphical Benchmark Information Service (GBIS) on the World Wide Web (WWW) to display interactively graphs of user-selected benchmark results from the GENESIS and PARKBENCH benchmark suites.
Comparison Between the Morphological Skeleton and Morphological Shape Decomposition
Authors: Joseph M. Reinhardt, William E. Higgins
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1996)

The morphological skeleton and morphological shape decomposition (MSD) are two popular approaches for morphological shape representation. Each method represents an object as an algebraic combination of a number of components, where each component is given by a locus of points dilated by a specified structuring-element homothetic. This correspondence develops a theoretical comparison between the two methods. Combining the theoretical results with several representation cost measures, we make a concrete comparison of the efficiency of the two methods. The results indicate that for complex objects¿i.e., objects requiring a full range of homothetic sizes in the morphological skeleton representation¿the MSD represents objects more efficiently than the morphological skeleton for three of four suggested cost measures.
MedModel: healthcare specific simulation software
Authors: Jeffrey B. Schulz
Venue: Proceedings of the 27th conference on Winter simulation (1995)

Since its release in 1993, MedModel has continued to make substantial strides in the evolution of healthcare simulation software. Until its arrival, the complex interdependencies and extreme number of variable outcomes exhibited by the ordinary healthcare system restricted the use of simulation to large forecasting or trend analysis models. MedModel was specifically designed to be simple to use and tailorable to the needs of healthcare managers, engineers and clinicians. As such, it provides a basis for the comprehensive evaluation of large, complex problems which are representative of healthcare systems in general. This paper serves as a preliminary examination of some of MedModel's comprehensive features and capabilities carefully designed to solve hospital and healthcare specific simulation problems.
From programming environments to environments for designing
Authors: Terry Winograd
Venue: Communications of the ACM (1995)

Though there have been advances in end-user programming, complex applications still need professional developers. This inspired look at the future of creating complex software explores the shift from programming environments to design environments, discussing environments that help developers satisfy end-users' cognitive needs and help deal with contextual issues such as the aesthetic, practical, and social properties of the application and the users. A strong case is made that design environments will need to provide robust support for communication between developers and end users.
Evaluation of TCP Vegas: emulation and experiment
Authors: Jong Suk Ahn, Peter B. Danzig, Zhen Liu, Limin Yan
Venue: ACM SIGCOMM Computer Communication Review (1995)

This paper explores the claims that TCP Vegas [2] both uses network bandwidth more efficiently and achieves higher network throughput than TCP Reno [6]. It explores how link bandwidth, network buffer capacity, TCP receiver acknowledgment algorithm, and degree of network congestion affect the relative performance of Vegas and Reno.
HoloSketch: a virtual reality sketching/animation tool
Authors: Michael F. Deering
Venue: ACM Transactions on Computer-Human Interaction (TOCHI) (1995)

This article describes HoloSketch, a virtual reality-based 3D geometry creation and manipulation tool. HoloSketch is aimed at providing nonprogrammers with an easy-to-use 3D &ldquo;What-You-See-Is-What-You-Get&rdquo; environment. Using head-tracked stereo shutter glasses and a desktop CRT display configuration, virtual objects can be created with a 3D wand manipulator directly in front of the user, at very high accuracy and much more rapidly than with traditional 3D drawing systems. HoloSketch also supports simple animation and audio control for virtual objects. This article describes the functions of the HoloSketch system, as well as our experience so far with more-general issues of head-tracked stereo 3D user interface design.
Performance analysis of MD5
Authors: Joseph D. Touch
Venue: Proceedings of the conference on Applications, technologies, architectures, and protocols for computer communication (1995)

MD5 is an authentication algorithm proposed as the required implementation of the authentication option in IPv6. This paper presents an analysis of the speed at which MD5 can be implemented in software and hardware, and discusses whether its use interferes with high bandwidth networking. The analysis indicates that MD5 software currently runs at 85 Mbps on a 190 Mhz RISC architecture, a rate that cannot be improved more than 20-40%. Because MD5 processes the entire body of a packet, this data rate is insufficient for current high bandwidth networks, including HiPPI and FiberChannel. Further analysis indicates that a 300 Mhz custom VLSI CMOS hardware implementation of MD5 may run as fast as 256 Mbps. The hardware rate cannot support existing IPv4 data rates on high bandwidth links (800 Mbps HiPPI). The use of MD5 as the default required authentication algorithm in IPv6 should therefore be reconsidered, and an alternative should be proposed. This paper includes a brief description of the properties of such an alternative, including a sample alternate hash algorithm.
Scientists called upon to take actions
Authors: Xiaolei Qian
Venue: ACM SIGMOD Record (1996)

Once again, scientists were called upon to take greater role in the political process. And this time, they did! We report on the continuous debate on the nation's R D policy. We also cover funding opportunities from DoD and NSF.