ppxscal/embedding_network huggingface dataset:
Simulation based optimization
Authors: Alexander Shapiro
Venue: Proceedings of the 28th conference on Winter simulation (1996)

In this talk we consider a problem of optimizing an expected value function by Monte Carlo simulation methods. We discuss, somewhat in details, the stochastic counterpart (sample path) method where a relatively large sample is generated and the expected value function is approximated by the corresponding average function. Consequently the obtained approximation problem is solved by deterministic methods of nonlinear programming. One of advantages of this approach, compared with the classical stochastic approximation method, is that a statistical inference can be incorporated into optimization algorithms. This allows to develop a validation analysis, stopping rules and variance reduction techniques which in some cases considerably enhance numerical performance of the stochastic counterpart method.
Robust Stability of Quasipolynomials with Annular Uncertainties
Authors: J. Hocherman, J. Kogan, A. Leizarowitz, E. Zeheb
Venue: Multidimensional Systems and Signal Processing (1998)

The paper concerns Hurwitz stability of a family of quasipolynomials. Each coefficient of a quasipolynomial belongs to a prescribed annulus in the complex plane, and each delay belongs to a prescribed real interval. Computationally tractable necessary and sufficient robust stability conditions are the main result of the paper.
Accuracy Enhancement for Higher Derivatives using Chebyshev Collocation and a Mapping Technique
Authors: Wai Sun Don, Alex Solomonoff
Venue: SIAM Journal on Scientific Computing (1997)

A new method is investigated to reduce the roundoff error in computing derivatives using Chebyshev collocation methods. By using a grid mapping derived by Kosloff and Tal-Ezer, and the proper choice of the parameter $\alpha$, the roundoff error of the $k$th derivative can be reduced from $O(N^{2k})$ to $O((N \lge)^k)$, where $\epsilon$ is the machine precision and $N$ is the number of collocation points. This drastic reduction of roundoff error makes mapped Chebyshev methods competitive with any other algorithm in computing second or higher derivatives with large $N$. Several other aspects of the mapped Chebyshev differentiation matrix are also studied, revealing that the mapped Chebyshev methods require much less than $\pi$ points to resolve a wave; the eigenvalues are less sensitive to perturbation by roundoff error; and larger time steps can be used for solving PDEs. All these advantages of the mapped Chebyshev methods can be achieved while maintaining spectral accuracy.
An Iterative Riemann Solver for Relativistic Hydrodynamics
Authors: Wenlong Dai, Paul R. Woodward
Venue: SIAM Journal on Scientific Computing (1997)

An approximate method for solving the Riemann problem is needed to construct Godunov schemes for relativistic hydrodynamical equations. Such an approximate Riemann solver is presented in this paper which treats all waves emanating from an initial discontinuity as themselves discontinuous. Therefore, jump conditions for shocks are approximately used for rarefaction waves. The solver is easy to implement in a Godunov scheme and converges rapidly for relativistic hydrodynamics. The fast convergence of the solver indicates the potential of a higher performance of a Godunov scheme in which the solver is used.
Worst Case Length of Nearest Neighbor Tours for the Euclidean Traveling Salesman Problem
Authors: L. Tassiulas
Venue: SIAM Journal on Discrete Mathematics (1997)

The worst case length of a tour for the Euclidean traveling salesman problem produced by the nearest neighbor (NN) heuristic is studied in this paper. Nearest neighbor tours for a set of arbitrarily located points in the $d$-dimensional unit cube are considered. A technique is developed for bounding the worst case length of a tour. It is based on identifying sequences of {\it coverings} of $[0,1]^d$. Each covering ${\cal P}_k$ consists of sets $C_i$, with diameter bounded by the {\it diameter} $D({\cal P}_k)$ of the covering. For every sequence of coverings a bound is obtained that depends on the cardinality of the coverings and their diameters. The task of bounding the worst case length of an NN tour is reduced to finding appropriate sequences of coverings. Using coverings produced by the rectangular lattice with appropriately shrinking diameter, it is shown that the worst case length of an NN tour through $N$ points in $[0,1]^d$ is bounded by $[d\sqrt{d}/(d-1)] N^{(d-1)/d}+o(N^{(d-1)/d})$. For the unit square the tighter bound $2.482\sqrt{N}+o(\sqrt{N})$ is obtained using regular hexagonal lattice coverings.
Dynamic rescheduling of a job shop: a simulation study
Authors: Anand S. Kunnathur, Sriram Sampath, P. S. Sundararagharan
Venue: Proceedings of the 28th conference on Winter simulation (1996)

The development of a rule based Expert System (ES), driven by a discrete event simulation model, that performs dynamic shop scheduling is described. Based on a flowtime prediction heuristic that we have developed and base-line runs to establish the efficacy of scheduling strategies such as SPT, Critical Ratio, Total Work etc, a re-scheduling based dispatching strategy is investigated in a dynamic job shop environment. The results are discussed and analyzed.
Sequential optimisation without state space exploration
Authors: A. Mehrotra, S. Qadeer, V. Singhal, R. K. Brayton, A. Aziz, A. L. Sangiovanni-Vincentelli
Venue: Proceedings of the 1997 IEEE/ACM international conference on Computer-aided design (1997)

We propose an algorithm for area optimization of sequential circuits through redundancy removal. The algorithm finds compatible redundancies by implying values over nets in the circuit. The potentially exponential cost of state space traversal is avoided and the redundancies found can all be removed at once. The optimized circuit is a safe delayed replacement of the original circuit. The algorithm computes a set of compatible sequential redundancies and simplifies the circuit by propagating them through the circuit. We demonstrate the efficacy of the algorithm even for large circuits through experimental results on benchmark circuits.
SoftCost-Ada: user experiences and lessons learned at the age of three
Authors: Donald J. Reifer
Venue: Proceedings of the conference on TRI-ADA '90 (1990)

This paper debunks the myth that there is no hard data proving Ada's cost-effectiveness. SoftCost- Ada is a modern estimating package used to predict costs and schedules for software-intensive projects which employ the Ada programming language, object-oriented methods, new development paradigms, workstation-based environments, and modern software engineering techniques. The package's underlying model is based upon an extensive analysis of 75 completed projects within the United States which have delivered in excess of 30 million lines of Ada source code for a variety of military and commercial applications. The purpose of this paper is to communicate the lessons that we have learned since we introduced the package in 1987 so that others within the community can benefit from our experiences and economic analyses. To achieve this goal, the paper first briefly introduces the reader to the SoftCost-Ada estimating model, the database upon which it is built, and the tradeoff laws which it employs to investigate Ada costs, schedules, and risks. The paper then focuses on the economic issues related to Ada identified by industry leaders and users of the SoftCost-Ada package. Finally, the paper concludes by exploring the lessons learned relative to Ada economics by investigating the actual data collected from 15 firms.
BASEMENT: An Architecture and Methodology for Distributed Automotive Real-Time Systems
Authors: Hans Hansson, Harold Lawson, Olof Bridal, Christer Eriksson, Sven Larsson, Henrik Lön, Mikael Strömberg
Venue: IEEE Transactions on Computers (1997)

BASEMENTTM is a distributed real-time architecture developed for vehicle internal use in the automotive industry. BASEMENT covers application development, as well as the hardware and software that provide execution and communication support. This paper gives an overview of the BASEMENT concept, as well as presenting two system realizations. The first realization is based on the commercial real-time kernel Rubus, while the second is an ultra-dependable architecture (DACAPO) with provisions for fault tolerance at various system levels.BASEMENT is designed for the automotive systems of the future. These systems will be required to simultaneously handle multiple safety critical functions and a large number of less critical functions. All of these features are to be provided at a production cost substantially lower than that of current systems, and, at the same time, with a reliability allowing vehicles to be built without mechanical backup systems, even for safety critical subsystems such as braking and steering.The key constituents of the concept are: 1) resource sharing (multiplexing) of processing and communication resources, 2) a guaranteed real-time service for safety critical applications, 3) a best-effort service for nonsafety critical applications, 4) a communication infrastructure providing efficient communication between distributed devices, 5) a program development methodology allowing resource independent and application oriented development of application software, and 6) a straightforward and well-defined operation principle enabling efficient fault tolerance mechanisms to be employed.
Computational geometry column 31
Authors: Joseph O'Rourke
Venue: ACM SIGACT News (1997)

Several topics related to packing on a sphere are discussed: packing points, packing lines through the center, and packing k-flats in dimension d.
Columbia digital news system an environment for briefing and search over multimedia information
Authors: Alfred Aho, Shih-Fu Chang, Kathleen McKeown, Dragomir Radev, John Smith, Kazi Zaman
Venue: Proceedings of the IEEE international forum on Research and technology advances in digital libraries (1997)

In this paper we describe an ongoing research project called the Columbia Digital News System. The goal of this project is to develop a suite of effective interoperable tools with which people can find relevant information (text, images, video, and structured documents) from distributed sources and track it over a period of time. Our initial focus is on the development of a system with which researchers, journalists, and students can keep track of current news events in specific areas.
Manipulation of music for melody matching
Authors: Alexandra L. Uitdenbogerd, Justin Zobel
Venue: Proceedings of the sixth ACM international conference on Multimedia (1998)

Many types of user would find it valuable to search collections of music via queries representing music fragments, but such searching requires a reliable technique for identifying whether a provided fragment occurs within a piece of music. The problem of matching fragments to music is made difficult by the psychology of music perception, because literal matching may have litile relation to perceived melodic similarity, and by the interactions between the multiple parts of typical pieces of music. In this paper we analyse the propeties of music, music perception, and music database users, and use the analysis to propose alternative techniques for extracting monophonic melodies from polyphonic music; we believe that such melodies can subsequently be used for matching of queries to data. We report on experiments with music listeners, which rank our proposed techniques for extracting melodies.
Compound types for Java
Authors: Martin Büchi, Wolfgang Weck
Venue: ACM SIGPLAN Notices (1998)

Type compatibility can be defined based on name equivalence, that is, explicit declarations, or on structural matching. We argue that component software has demands for both. For types expressing individual contracts, name equivalence should be used so that references are made to external semantical specifications. For types that are composed of several such contracts, the structure of this composition should decide about compatibility.We introduce compound types as the mechanism to handle such compositions. To investigate the integrability into a strongly typed language, we add compound types to Java and report on a mechanical soundness proof of the resulting type system.Java users benefit from the higher expressiveness of the extended type system. We introduce compound types as a strict extension of Java, that is without invalidating existing programs. In addition, our proposal can be implemented on the existing Java Virtual Machine.
Online evaluation in WWW-based courseware
Authors: Lucio C. Tinoco, N. Dwight Barnette, Edward A. Fox
Venue: ACM SIGCSE Bulletin (1997)

The QUIZIT system has been developed to support adaptive as well as standard testing, along with automatic grading and record keeping, using the WWW as a delivery vehicle. In connection with our Interactive Learning with a Digital Library in Computer Science project, we have applied QUIZIT to help with a master's level course as well as a large freshman level service course. Preliminary testing has led to various improvements, and it appears that QUIZIT will be well received by both instructors and students. It should port easily to a variety of environments and so could be widely used at other institutions as well.
Centroid based Multilayer Perceptron Networks
Authors: Mikko Lehtokangas, Jukka Saarinen
Venue: Neural Processing Letters (1998)

In this study we investigate a hybrid neural network architecture for modelling purposes. The proposed network is based on the multilayer perceptron (MLP) network. However, in addition to the usual hidden layers the first hidden layer is selected to be a centroid layer. Each unit in this new layer incorporates a centroid that is located somewhere in the input space. The output of these units is the Euclidean distance between the centroid and the input. The centroid layer clearly resembles the hidden layer of the radial basis function (RBF) networks. Therefore the centroid based multilayer perceptron (CMLP) networks can be regarded as a hybrid of MLP and RBF networks. The presented benchmark experiments show that the proposed hybrid architecture is able to combine the good properties of MLP and RBF networks resulting fast and efficient learning, and compact network structure.
Operators for recursion
Authors: Edward V. Eusebi
Venue: ACM SIGAPL APL Quote Quad (1985)

Recursion is frequently used in functional programming languages. In LISP, it is the primary means of traversing data structures, and, along with COND, is instrumental in controlling program flow. In APL2, the generalization of arrays to include arrays of arrays encourages the use of recursion. This usage is enhanced by the generalization of, and extensions to, operators. In particular, the ability to define operators allows us to create operators which simplify the coding of recursive logic. This paper studies the use of operators to provide program control for solutions to problems which involve recursion. For the most part, iteration on the elements of a list is used to replace recursive function calls. The program control methods used in this paper are introduced in a companion paper, Operators for Program Control (Eusebi[3]). The reader is encouraged to read that paper first.
Algorithm 789: SLTSTPAK: a test package for Sturm-Liouville solvers
Authors: J. D. Pryce
Venue: ACM Transactions on Mathematical Software (TOMS) (1999)

We give technical details of the Sturm-Liouville test package SLTSTPAK, complementing the companion article (this issue) on its design. SLTSTPAK comprises the follwing : a specification of how to write a routine TSTSET containing a set of Sturm-Liouville problems; a number of routines that act as a harness between a TSTSET, written to this specification, and a driver program. A set of 60 standard problems is provided, but it is simple to replace this by another one.
A comparison of reliable multicast protocols
Authors: Brian Neil Levine, J.J. Garcia-Luna-Aceves
Venue: Multimedia Systems (1998)

We analyze the maximum throughput that known classes of reliable multicast transport protocols can attain. A new taxonomy of reliable multicast transport protocols is introduced based on the premise that the mechanisms used to release data at the source after correct delivery should be decoupled from the mechanisms used to pace the transmission of data and to effect error recovery. Receiver-initiated protocols, which are based entirely on negative acknowledgments (NAKS) sent from the receivers to the sender, have been proposed to avoid the implosion of acknowledgements (ACKS) to the source. However, these protocols are shown to require infinite buffers in order to prevent deadlocks. Two other solutions to the ACK-implosion problem are tree-based protocols and ring-based protocols. The first organize the receivers in a tree and send ACKS along the tree; the latter send ACKS to the sender along a ring of receivers. These two classes of protocols are shown to operate correctly with finite buffers. It is shown that tree-based protocols constitute the most scalable class of all reliable multicast protocols proposed to date.
Distributed simulation of spatially explicit ecological models
Authors: Kevin Glass, Marilynn Livingston, John Conery
Venue: Proceedings of the eleventh workshop on Parallel and distributed simulation (1997)

Large-scale ecological simulations are natural candidates for distributed discrete event simulation. In optimistic simulation of spatially explicit models, a difficult problem arises when individuals migrate between physical regions simulated by different logical processes. We present a solution to this problem that uses shared object states. Shared states allow for efficient communication between LPs and for early detection of canceled events. We briefly describe an optimistic simulation environment called EcoKit, which operates on top of the WarpKit implementation of Time Warp. Our experiments with this system on a shared memory multiprocessor show that EcoKit promises to scale well both with the number of processors and the number of individuals simulated.
Performance of a conservative simulator of ATM networks
Authors: John G. Cleary, Jya-Jang Tsai
Venue: ACM SIGSIM Simulation Digest (1997)

This paper describes an implementation of a conservative parallel distributed simulator that has been used to simulate a high fidelity model of ATM networks. Important optimisations of the simulator for this application are described. The performance of the simulator is reported on up to 12 processors and compared with a sequential implementation. It is seen that the simulator gives good speedup and better performance than the sequential implementation. It is noted that the low overhead of the simulator relies on there being good lookahead in realistic models of ATM networks. Some situations where this lookahead is significantly reduced are described together with future extensions to fix these problems.
Discrete-event simulation input process modeling
Authors: Lawrence M. Leemis
Venue: Proceedings of the 28th conference on Winter simulation (1996)

General guidelines for selecting probabilistic input models as part of a discrete-event simulation study are presented. Two short examples illustrating input modeling decisions are also presented, as opposed to a complete treatment of the subject.
Simulation and education
Venue: Proceedings of the 17th conference on Winter simulation (1985)

The quality and credibility of simulation models are increasing in importance, along with a continual increase in the use of these models themselves. In the final analysis, we all depend on quality having been built into the simulation models designed by many people in diverse disciplines. As educators we must instill professional pride, habitual validation and analysis of data, goal-oriented creativity, and a sense of ethical practice into the simulationists of the future.
STARTS: Stanford proposal for Internet meta-searching
Authors: Luis Gravano, Chen-Chuan K. Chang, Héctor García-Molina, Andreas Paepcke
Venue: Proceedings of the 1997 ACM SIGMOD international conference on Management of data (1997)

Document sources are available everywhere, both within the internal networks of organizations and on the Internet. Even individual organizations use search engines from different vendors to index their internal document collections. These search engines are typically incompatible in that they support different query models and interfaces, they do not return enough information with the query results for adequate merging of the results, and finally, in that they do not export metadata about the collections that they index (e.g., to assist in resource discovery). This paper describes STARTS, an emerging protocol for Internet retrieval and search that facilitates the task of querying multiple document sources. STARTS has been developed in a unique way. It is not a standard, but a group effort coordinated by Stanford's Digital Library project, and involving over 11 companies and organizations. The objective of this paper is not only to give an overview of the STARTS protocol proposal, but also to discuss the process that led to its definition.
On GMW Designs and Cyclic Hadamard Designs
Authors: Wen--Ai Jackson, Peter R. Wild
Venue: Designs, Codes and Cryptography (1997)

We generalise results of Jackson concerning cyclic Hadamard designs admitting SL(2,2)^n as a point transitive automorphism group. The generalisation concerns the designs of Gordon, Mills and Welch and we characterise these as designs admitting GM(m,q)^n acting in a certain way. We also generalise a construction given by Maschietti, using hyperovals, of cyclic Hadamard designs, and characterise these amongst the designs of Gordon, Mills and Welch.
Quick conservative causality analysis
Authors: Ellen M. Sentovich
Venue: Proceedings of the 10th international symposium on System synthesis (1997)

The causality problem is that of determining if a combinational circuit with cycles has acceptable behavior: that for all inputs the outputs are well defined and stable. While the problem manifests itself at the circuit level, it usually originates at the system level. It may arise when a system is designed as a collection of modules: when composed, cycles are discovered in the ensemble. One must analyze these cycles to correct possible errors or to capture the correct behavior appropriately for further synthesis. Previously published algorithms use iterated ternary logic simulation. This is correct and robust, but expensive and in many cases overkill. We propose a more efficient but conservative algorithm based on applying standard logic synthesis techniques of increasing power. We present initial results to demonstrate the practicality of this approach.
A Transfinite Interpolation Method of Grid Generation Based on Multipoints
Authors: Yuan Chang Liou, Yih Nen Jeng
Venue: Journal of Scientific Computing (1998)

In this work two algebraic grid generation methods based on the Soni-linear and Soni-Hermite transfinite interpolation methods, respectively, are developed. The necessary data of the transfinite interpolation formulas, such as coordinates and grid angles, are determined by more than one points along all the boundaries. The number of dependent points increases and the influence factors associated to these points decrease as the point of interesting moves away from a boundary. Several test cases are examined to show the proposed methods' capability.