ppxscal/embedding_network huggingface dataset:
Supporting valid-time indeterminacy
Authors: Curtis E. Dyreson, Richard Thomas Snodgrass
Venue: ACM Transactions on Database Systems (TODS) (1998)

In valid-time indeterminacy it is known that an event stored in a database did in fact occur, but it is not known exactly when. In this paper we extend the SQL data model and query language to support valid-time indeterminacy. We represent the occurrence time of an event with a set of possible instants, delimiting when the event might have occurred, and a probability distribution over that set. We also describe query language constructs to retrieve information in the presence of indeterminacy. These constructs enable users to specify their credibility in the underlying data and their plausibility in the relationships among that data. A denotational semantics for SQL's select statement with optional credibility and plausibility constructs is given. We show that this semantics is reliable, in that it never produces incorrect information, is maximal, in that if it were extended to be more informative, the results may not be reliable, and reduces to the previous semantics when there is no indeterminacy. Although the extended data model and query language provide needed modeling capabilities, these extensions appear initially to carry a significant execution cost. A contribution of this paper is to demonstrate that our approach is useful and practical. An efficient representation of valid-time indeterminacy and efficient query processing algorithms are provided. The cost of support for indeterminacy is empirically measured, and is shown to be modest. Finally, we show that the approach is general, by applying it to the temporal query language constructs being proposed for SQL3.
The Transmogrifier-2: a 1 million gate rapid prototyping system
Authors: David M. Lewis, David R. Galloway, Marcus van Ierssel, Jonathan Rose, Paul Chow
Venue: Proceedings of the 1997 ACM fifth international symposium on Field-programmable gate arrays (1997)

This paper describes the Transmogrifier-2, a second generation multi-FPGA system. The largest version of the system will comprise 16 boards that each contain two Altera 10K50 FPGAs, four I-cube interconnect chips, and up to 8 Mbytes of memory. The inter-FPGA routing architecture of the TM-2 uses a novel interconnect structure, a non-uniform partial crossbar, that provides a constant delay between any two FPGAs in the system. The TM-2 architecture is modular and scalable, meaning that various sized systems can be constructed from the same board, while maintaining routability and the constant delay feature. Other features include a system-level programmable clock that allows single-cycle access to off-chip memory, and programmable clock waveforms with resolution to 10ns. The first Transmogrifier-2 boards have been manufactured and are functional. They have recently been used successfully in some simple graphics acceleration applications.
A Heuristic Storage for Minimizing Access Time of Arbitrary Data Patterns
Authors: Mayez A. Al-Mouhamed, Steven S. Seiden
Venue: IEEE Transactions on Parallel and Distributed Systems (1997)

The serialization of memory accesses is a major limiting factor in high performance SIMD computers. The data patterns or templates that are accessed by a program can be perceived by the compiler, and, therefore, the design of dynamic storage schemes that minimize conflicts may dramatically improve performance.The problem of finding storage schemes that minimize the access time of arbitrary sets of power-of-two data patterns is proved to be NP-complete. We propose linear address transformations that can be dynamically applied by each processing element for mapping array references onto memories. An efficient approach for combining the constraints of different access patterns into one single linear address transformation is presented. We prove that finding the transformation that minimizes the access time is reducible to N-coloring, where N is the number of parallel memories. Using coloring heuristics, storage schemes are investigated with respect to minimizing the implementation cost (perfect storage) and overall access conflicts (semiperfect storage).Results show that the perfect-storage may deviate on the average by 20% from the optimum access time in the case of 10 arbitrary data patterns and 16 memories. However, semiperfect schemes lead to dramatic reduction of the degree of conflict compared to perfect-schemes. The proposed heuristic storage largely outperforms interleaving and row-column-diagonals storages. The method can be implemented as compiler procedure for synthesizing storage schemes that promote parallel access to arbitrary sets of data patterns.
Conversational group service
Authors: Alexander B. Romanovsky
Venue: ACM SIGOPS Operating Systems Review (1997)

The purpose of this paper is to propose a way of tolerating software (design) faults in distributed systems relying on the well-known conversation (atomic action) approach. To do this, we shall consider differences between two programming paradigms: group communication and conversations, and discuss how a group communication service can be used to provide design fault tolerance by conversations. The main characteristics and peculiarities of this new conversational group service are described.
Stability of the Diagonal Pivoting Method with Partial Pivoting
Authors: Nicholas J. Higham
Venue: SIAM Journal on Matrix Analysis and Applications (1997)

LAPACK and LINPACK both solve symmetric indefinite linear systems using the diagonal pivoting method with the partial pivoting strategy of Bunch and Kaufman [Math. Comp., 31 (1977), pp. 163--179]. No proof of the stability of this method has appeared in the literature. It is tempting to argue that the diagonal pivoting method is stable for a given pivoting strategy if the growth factor is small. We show that this argument is false in general and give a sufficient condition for stability. This condition is not satisfied by the partial pivoting strategy because the multipliers are unbounded. Nevertheless, using a more specific approach we are able to prove the stability of partial pivoting, thereby filling a gap in the body of theory supporting LAPACK and LINPACK.
Hierarchical Image Segmentation&mdash;Part I: Detection of Regular Curves in a Vector Graph
Authors: Stefano Casadei, Sanjoy Mitter
Venue: International Journal of Computer Vision (1998)

The problem of edge detection is viewed as a hierarchy of detection problems where the geometric objects to be detected (e.g., edge points, curves, regions) have increasing complexity and spatial extent. An early stage of the proposed hierarchy consists in detecting the regular portions of the visible edges. The input to this stage is given by a graph whose vertices are tangent vectors representing local and uncertain information about the edges. A model relating the input vector graph to the curves to be detected is proposed. An algorithm with linear time complexity is described which solves the corresponding detection problem in a worst-case scenario. The stability of curve reconstruction in the presence of uncertain information and multiple responses to the same edge is analyzed and addressed explicitly by the proposed algorithm.
Adaptive rate controlled, robust video communication over packet wireless networks
Authors: G. R. Rajugopal, R. H. M. Hafez
Venue: Mobile Networks and Applications (1998)

Video transmission over wireless packet networks is gaining importance due to the concept of universal personal communication. Further, it is considered an important step towards wireless multimedia. The challenge however is to achieve good video quality over mobile channels, where typically the channel conditions vary due to signal fading. Hence this paper investigates adaptive rate controlled video transmission for robust video communication under packet wireless environment. A combination of mobile and an ATM backbone network is assumed in this work. An error resilient design for the video coder, as proposed in Rajugopal et al. (1996) is employed here. This video coder comprises wavelet transform (WT), multi-resolution motion estimation (MRME) and a robust design for zero tree quantization. Two configurations, one employing MRME and the other using 1D-WT for temporal analysis, are considered for the video coder. Adaptive dynamic rate control is required to adapt the video communication to the channel conditions. It provides more channel protection when the channel is severe and improves the source rate and hence the performance when the conditions are favorable. An algorithm for dynamic rate control under varying channel conditions is proposed in this paper. It is evaluated under narrowband and broadband channel conditions. From the results, it is concluded that the dynamic rate control is very effective in optimizing the quality under varying mobile channel conditions. It was observed that the dynamic rate control provides at least an acceptable video quality under severe channel conditions and a good video quality when the channel conditions are favorable.
Limits of Singularly Perturbed Control Problems with Statistical Dynamics of Fast Motions
Authors: Alexander Vigodner
Venue: SIAM Journal on Control and Optimization (1997)

We describe the limit behavior of admissible trajectories in a singularly perturbed control system as the small parameter tends to zero. A general case is considered where, in the limit, the fast motion may infinitely rapidly oscillate in time. Invariant measures of the parameterized fast flow are employed to describe the limit behavior and construct the limit control problem. The notion of relatively slow controls is introduced. Approximating properties of the limit problem within the families of relatively slow controls are verified. The results are illustrated by examples.
A multilevel approach to intelligent information filtering: model, system, and evaluation
Authors: J. Mostafa, S. Mukhopadhyay, M. Palakal, W. Lam
Venue: ACM Transactions on Information Systems (TOIS) (1997)

In information-filtering environments, uncertainties associated with changing interests of the user and the dynamic document stream must be handled efficiently. In this article, a filtering model is proposed that decomposes the overall task into subsystem functionalities and highlights the need for multiple adaptation techniques to cope with uncertainties. A filtering system, SIFTER, has been implemented based on the model, using established techniques in information retrieval and artificial intelligence. These techniques include document representation by a vector-space model, document classification by unsupervised learning, and user modeling by reinforcement learning. The system can filter information based on content and a user's specific interests. The user's interests are automatically learned with only limited user intervention in the form of optional relevance feedback for documents. We also describe experimental studies conducted with SIFTER to filter computer and information science documents collected from the Internet and commercial database services. The experimental results demonstrate that the system performs very well in filtering documents in a realistic problem setting.
Using intelligent agents to change the delivery of education (poster)
Authors: John Rosbottom, Claude Moulin
Venue: ACM SIGCSE Bulletin (1998)

We present work done on the use of multiple intelligent agents as teaching agents, and discuss some more general applications for agent technology in education.
A Construction for Multisecret Threshold Schemes
Authors: Wen-Ai Jackson, Keith M. Martin, Christine M. O'Keefe
Venue: Designs, Codes and Cryptography (1996)

A multisecret threshold scheme is a system that protects a number of secrets (or keys) among a group of participants, as follows. Given a set of n participants, there is a secret s_K associated with each k&ndash;subset K of these participants. The scheme ensures that s_K can be reconstructed by any group of t participants in K ( 1\leq t\leq k). A lower bound has been established on the amount of information that participants must hold in order to ensure that any set of up to w participants (0 \leq w \leq n-k+t-1) cannot obtain any information about a secret with which they are not associated. In this paper, for parameters t=2 and w=n-k+t-1, we give a construction for multisecret threshold schemes that satisfy this bound.
Maximal Partial Spreads and Flocks
Authors: Norman L. Johnson, Guglielmo Lunardon
Venue: Designs, Codes and Cryptography (1997)

Denote by F a flock of a quadratic cone ofPG(3,q), by S(F) the spread of PG(3,q) associated with F and by l&infin; the common line of the base reguli. Suppose that there are two lines not transversal to a base regulus which share the same lines of S(F). Then we prove that F is either linear or a Kantor-Knuth semifield flock. Using this property we can extend the result of J3 on derivable flocks proving that, if a set of q+1 lines of S(F) defines a derivable net different from a base regulus-net, then F is either linear or a Kantor-Knuth semifield flock. Moreover if l&infin; is not a component of the derivable net, then F is linear.
The OT idea life-cycle (panel): from eureka! to shrink wrap
Authors: Laura Hill, Bruce Anderson, Adele Goldberg, Gregor Kiczales, Colin Scott, Kevin Tyson
Venue: ACM SIGPLAN Notices (1997)

Over the past years, the Object Technology community has seen the birth of a number of new technology ideas that have changed the way we do computing. These ideas have affected compiler design, analysis approaches, project management techniques, user interface design, deployment strategies and implementation tactics. But where do these ideas come from? And how do they evolve? Do they address the needs as specified by members of the Object Community? Is there a way we can nurture the introduction and assimilation of these ideas to and by the community at large? And what are the market forces that bend ideas to their will. This panel will look at new ideas in Object Technology from a variety of perspectives and will attempt to get to the heart of the way that we, as technologists, create, buy, sell and grow ideas.
Simulation works: a panel discussion
Authors: William R. Lilegdon, Stuart Gittlitz, Randy D. Moore, Patrick Reardon
Venue: Proceedings of the 28th conference on Winter simulation (1996)

Construction operations are often repetitive not only in terms of time (the same tasks are performed over and over) but also in terms of space (the same tasks are repeated at several places, such as different floors in a high-rise building). Thus, construction simulation models in general must be cyclic to represent temporal repetitions, but also scaleable to represent spatial repetitions. This paper presents the mechanisms for preprocessor replacement and automatic code generation that have been designed and implemented to facilitate the development of scaleable simulation models in STROBOSCOPE, a general-purpose discrete-event simulation system developed by the authors. A relatively complex simulation model for the vertical transportation of people serves as an example to illustrate how to develop a completely scaleable model for the operation of an elevator in a building with any number of floors.
Hardware/Software Codesign from the RASSP Perspective
Authors: Geoffrey A. Frank, Bernard Clark, W. Bernard Schaming, William Kline
Venue: Journal of VLSI Signal Processing Systems (1997)

Hardware/Software Codesign refers to the simultaneous consideration of hardware and software within a system design. Hardware/Software Codesign is the co-development and co-verification of hardware and software through the use of simulation and/or emulation. The RASSP program, with its emphasis on high performance signal processing systems, has a particular perspective on Hardware/Software Codesign which is presented in this paper. However, many of the RASSP methods and tools can be applied more generally in the larger environment of embedded systems. This paper describes a generic Hardware/Software Codesign process, discusses tools and techniques used in the different phases of that process, and provides examples of efforts on these phases. In particular, it describes Hardware/Software Codesign as defined by RASSP, the Lockheed Martin ATL approach to Hardware/Software Codesign, and Hardware/Software Codesign tools developed by the Research Triangle Institute. This paper uses the RASSP SAR system benchmark as an example of Hardware/Software Codesign, and presents issues and designs for this system that were developed by Lockheed Martin ATL and RTI using Hardware/Software Codesign.
So you want to be a simulation consultant
Authors: John S. Carson,  II
Venue: Proceedings of the 28th conference on Winter simulation (1996)

This presentation is for those who want to be a simulation consultant, whether in an independent consulting company or within a consulting group in a larger company. Both practical project management and good technical fundamentals are critical for success. Does a simulation consultant need to be an expert in all disciplines? Does he or she need to be an engineer, a modeler, a statistician, and a computer scientist? The ideas presented in this tutorial are based on many years of practical simulation experience. Examples from real world projects will be used to illustrate various points. The author's woeful experience will be used to illustrate pitfalls to avoid.
On the anomaly of ran1() in Monte Carlo pricing of financial derivatives
Authors: Akira Tajima, Syoiti Ninomiya, Shu Tezuka
Venue: Proceedings of the 28th conference on Winter simulation (1996)

Recently, Paskov reported that, the use of a certain pseudo-random number generator, ran1() which is given in Numerical Recipes in C First Edition, makes Monte Carlo simulations for pricing financial derivatives converge to wrong values. In this paper, we trace Paskov's experiment, investigate the characteristics and the generation algorithm of the pseudo-random number generator in question, and explain why the wrong convergences occur. We also present a method for avoiding such wrong convergences. A variance reduction procedure is applied together with the method to obtain more precise value, and the effectiveness is examined.
On the need for predictable floating-point arithmetic in the programming languages Fortran 90 and C/C++
Authors: Dennis Verschaeren, Annie Cuyt, Brigitte Verdonk
Venue: ACM SIGPLAN Notices (1997)

During the past decade the IEEE 754 standard for binary floating-point arithmetic has been very successful. Many of today's hardware platforms conform to this standard and compilers should make floating-point functionality available to programmers through high-level programming languages. They should also implement certain features of the IEEE 754 standard in software, such as the input and output conversions to and from the internal binary representation of numbers. In this report, a number of Fortran 90 and C/C++ compilers for workstations as well as personal computers will be screened with respect to their IEEE conformance. It will be shown that most of these compilers do not conform to the IEEE standard and that shortcomings are essentially due to their respective programming language standards which lack attention for the need of predictable floating-point arithmetic.
Fault Tolerant Algorithms for Broadcasting on the Star Graph Network
Authors: N. W. Lo, Bradley S. Carlson, D. L. Tao
Venue: IEEE Transactions on Computers (1997)

Fault tolerant algorithms are presented for broadcasting on the star graph. In our algorithm, fault tolerance is achieved by constructing an isomorphism of the star network, such that the faulty nodes minimally disrupt the message passing sequence. It is shown that, in the presence of r (1 ¿r¿k¿ 2) faults, at most r extra steps are required by our algorithm to perform a one-to-all broadcasting in the k-star network. Our algorithm has the same time complexity as an optimal broadcasting algorithm, and, since it takes advantage of the hierarchical nature of the star graph network, it can be implemented easily. Our algorithm can also be used to perform all-to-all broadcasting in a faulty star graph.
Improving end-to-end performance of the Web using server volumes and proxy filters
Authors: Edith Cohen, Balachander Krishnamurthy, Jennifer Rexford
Venue: ACM SIGCOMM Computer Communication Review (1998)

The rapid growth of the World Wide Web has caused serious performance degradation on the Internet. This paper offers an end-to-end approach to improving Web performance by collectively examining the Web components --- clients, proxies, servers, and the network. Our goal is to reduce user-perceived latency and the number of TCP connections, improve cache coherency and cache replacement, and enable prefetching of resources that are likely to be accessed in the near future. In our scheme, server response messages include piggybacked information customized to the requesting proxy. Our enhancement to the existing request-response protocol does not require per-proxy state at a server, and a very small amount of transient per-server state at the proxy, and can be implemented without changes to HTTP 1.1. The server groups related resources into volumes (based on access patterns and the file system's directory structure) and applies a proxy-generated filter (indicating the type of information of interest to the proxy) to tailor the piggyback information. We present efficient data structures for constructing server volumes and applying proxy filters, and a transparent way to perform volume maintenance and piggyback generation at a router along the path between the proxy and the server. We demonstrate the effectiveness of our end-to-end approach by evaluating various volume construction and filtering techniques across a collection of large client and server logs.
Time--Space Lower Bounds for Directed st-Connectivity on Graph Automata Models
Authors: Greg Barnes, Jeff A. Edmonds
Venue: SIAM Journal on Computing (1998)

Directed st-connectivity is the problem of detecting whether there is a path from a distinguished vertex s to a distinguished vertex t in a directed graph. We prove time--space lower bounds of $ST = \Omega({n^{2} \log n \over \log (n \log n/S)})$ and $S^{1 \over 2}T = \Omega(m (n \log n)^{1 \over 2})$ for directed st-connectivity on Cook and Rackoff's jumping automaton for graphs (JAG) model [SIAM J. Comput., 9(1980), pp. 636--652], where n is the number of vertices and m the number of edges in the input graph, S is the space, and T the time used by the JAG. These lower bounds are simple and elegant, they approach the known upper bound of T = O(m) when S approaches $\Theta(n \log n)$, and they are the first time--space tradeoffs for JAGs with an unrestricted number of jumping pebbles.