ppxscal/embedding_network huggingface dataset:
A formal approach to nonlinear analog circuit verification
Authors: Lars Hedrich, Erich Barke
Venue: Proceedings of the 1995 IEEE/ACM international conference on Computer-aided design (1995)

This contribution presents an approach to nonlinear dynamic analog circuit verification. The input-output behavior of two systems is analyzed to check whether they are functionally similar. The algorithm compares the implicit nonlinear state space descriptions of the two systems on the same or on different levels of abstraction by sampling the state spaces and by building a nonlinear one-to-one mapping of the state spaces. Some examples demonstrate the feasibility of our approach.
Optimal evaluation of array expressions on massively parallel machines
Authors: Siddhartha Chatterjee, John R. Gilbert, Robert Schreiber, Shang-Hua Teng
Venue: ACM Transactions on Programming Languages and Systems (TOPLAS) (1995)

We investigate the problem of evaluating Fortran 90-style array expressions on massively parallel distributed-memory machines. On such a machine, an elementwise operation can be performed in constant time for arrays whose corresponding elements are in the same processor. If the arrays are not aligned in this manner, the cost of aligning them is part of the cost of evaluating the expression tree. The choice of where to perform the operation then affects this cost.We describe the communication cost of the parallel machine theoretically as a metric space; we model the alignment problem as that of finding a minimum-cost embedding of the expression tree into this space. We present algorithms based on dynamic programming that solve the embedding problem optimally for several communication cost metrics: multidimensional grids and rings, hypercubes, fat-trees, and the discrete metric. We also extend our approach to handle operations that change the shape of the arrays.
Paradise: a database system for GIS applications
Authors: CORPORATE The Paradise Team
Venue: Proceedings of the 1995 ACM SIGMOD international conference on Management of data (1995)

The goal of the Paradise project is to apply object-oriented and parallel database technology to the task of implementing a parallel GIS system capable of managing extremely large (multi-terabyte) data sets such as those that will be produced by the upcoming NASA EOSDIS project [Car92]. The project is focusing its resources on algorithms, processing, and storage techniques, and not on making new contributions to the data modeling, query language, or user interface domains.At the outset, we organized the Paradise project as two phases. The goal of first phase was to produce a client-server version of Paradise. The second phase of the project is to add support for tertiary storage and extend the software to run on clusters of workstations and "shared nothing" multiprocessors [Sto86]. Phase one of the project is now complete and has produced a usable, client-server version of the system whose performance and functionality is comparable to other integrated GIS systems [DKL+94].
Local Invariants For Recognition
Authors: Ehud Rivlin, Isaac Weiss
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1995)

Geometric invariants are shape descriptors that remain unchanged under geometric transformations such as projection or changing the viewpoint. A new method of obtaining local projective and affine invariants is developed and implemented for real images. Being local, the invariants are much less sensitive to occlusion than global invariants. The invariants¿ computation is based on a canonical method. This consists of defining a canonical coordinate system by the intrinsic properties of the shape, independently of the given coordinate system. Since this canonical system is independent of the original one, it is invariant and all quantities defined in it are invariant. The method was applied without the use of a curve parameter. This was achieved by fitting an implicit polynomial to an arbitrary curve in a vicinity of each curve point. Several configurations are treated: a general curve without any correspondence and curves with known correspondences of one or two feature points or lines. Experimental results for different 2D objects in 3D space are presented.
Optimal Layouts of Midimew Networks
Authors: Francis C. M. Lau, Guihai Chen
Venue: IEEE Transactions on Parallel and Distributed Systems (1996)

Midimew networks [4] are mesh-connected networks derived from a subset of degree-4 circulant graphs. They have minimum diameter and average distance among all degree-4 circulant graphs, and are better than some of the most common topologies for parallel computers in terms of various cost measures. Among the many midimew networks, the rectangular ones appear to be most suitable for practical implementation. Unfortunately, with the normal way of laying out these networks on a 2D plane, long cross wires that grow with the size of the network exist. In this paper, we propose ways to lay out rectangular midimew networks in a 2D grid so that the length of the longest wire is at most a small constant. We prove that these constants are optimal under the assumption that rows and columns are moved as a whole during the layout process.
The Effect of Program Behavior on Fault Observability
Authors: Nicolas S. Bowen, D. K. Pradhan
Venue: IEEE Transactions on Computers (1996)

Fault observability based on the behavior of memory references is studied. Traditional studies view memory as one monolithic entity that must completely work to be considered reliable. The usage patterns of a particular program's memory are emphasized here. This paper develops a new model for the successful execution of a program taking into account the usage of the data by extending a cache memory performance model. Three variations, based on well known allocation schemes, are presented (i.e., whether the program's storage is preallocated, dynamically allocated, or constrained in allocation). This is contrasted to traditional memory reliability calculations to show that the actual mean time to failure may be more optimistic when program behavior is considered. It also develops expressions for the probability of unobserved faults. With several studies reporting correlations between increased workloads and increased failure rates, a new theory is proposed here that provides an explanation for this behavior. The model studies several program traces demonstrating that increased workloads could cause an increase of the observed failure rates in the range of 32% to 53%.
Individual-user-centered facilities for improving digital library application productivities on the Internet
Authors: Stewart N. T. Shen
Venue: ACM SIGWEB Newsletter (1995)

We have been exploring ways to increase the productivity of digital library applications over the Internet.
Efficient support for irregular applications on distributed-memory machines
Authors: Shubhendu S. Mukherjee, Shamik D. Sharma, Mark D. Hill, James R. Larus, Anne Rogers, Joel Saltz
Venue: ACM SIGPLAN Notices (1995)

Irregular computation problems underlie many important scientific applications. Although these problems are computationally expensive, and so would seem appropriate for parallel machines, their irregular and unpredictable run-time behavior makes this type of parallel program difficult to write and adversely affects run-time performance.This paper explores three issues&mdash;partitioning, mutual exclusion, and data transfer&mdash;crucial to the efficient execution of irregular problems on distributed-memory machines. Unlike previous work, we studied the same programs running in three alternative systems on the same hardware base (a Thinking Machines CM-5): the CHAOS irregular application library, Transparent Shared Memory (TSM), and eXtensible Shared Memory (XSM). CHAOS and XSM performed equivalently for all three applications. Both systems were somewhat (13%) to significantly faster (991%) than TSM.
CYC, WordNet, and EDR: critiques and responses
Authors: Doug Lenat, George Miller, Toshio Yokoi
Venue: Communications of the ACM (1995)

I applaud Miller's WordNet project and feel that there is much in common in our approaches, even though there are fundamental differences in the two expressions of that spirit. Here, I list the four differences I noted, closing with a crucial observation concerning the common spirit in our work.
A rejection technique for sampling from T-concave distributions
Authors: Wolfgang Hörmann
Venue: ACM Transactions on Mathematical Software (TOMS) (1995)

A rejection algorithm that uses a new method for constructing simple hat functions for a unimodal, bounded density f is introduced called &ldquo;transformed density rejection.&rdquo; It is based on the idea of transforming f with a suitable transformation T such that T(f(x)) is concave. f is then called T-concave, and tangents of T(f(x)) in the mode and in a point on the left and right side are used to construct a hat function with a table-mountain shape. It is possible to give conditions for the optimal choice of these points of contact. With T= -1/xxx, the method can be used to construct a universal algorithm that is applicable to a large class of unimodal distributions, including the normal, beta, gamma, and t-distribution.
A Network Pump
Authors: Myong H. Kang, Ira S. Moskowitz, Daniel C. Lee
Venue: IEEE Transactions on Software Engineering (1996)

A designer of reliable multi-level secure (MLS) networks must consider covert channels and denial of service attacks in addition to traditional network performance measures such as throughput, fairness, and reliability. In this paper we show how to extend the NRL data Pump to a certain MLS network architecture in order to balance the requirements of congestion control, fairness, good performance, and reliability against those of minimal threats from covert channels and denial of service attacks. We back up our claims with simulation results.
A programming project: trimming the spring algorithm for drawing hypergraphs
Authors: Harri Klemetti, Ismo Lapinleimu, Erkki Mäkinen, Mika Sieranta
Venue: ACM SIGCSE Bulletin (1995)

Graph drawing problems provide excellent material for programming projects. As an example, this paper describes the results of an undergraduate project which dealt with hypergraph drawing. We introduce a practical method for drawing hypergraphs. The method is based on the spring algorithm, a well-known method for drawing normal graphs.
A speech-act-based office modeling approach
Authors: Esa Auramäki, Erkki Lehtinen, Kalle Lyytinen
Venue: ACM Transactions on Information Systems (TOIS) (1988)

In this paper methods and principles that help to analyze offices as systems of communicative action are explored. In communicative action, office agents create commitments through symbolic means. A SAMPO (Speech-Act-based office Modeling aPprOach), which studies office activities as a series of speech acts creating, maintaining, modifying, reporting, and terminating commitments, is presented. The main steps and methods in the office system specification are outlined and their application illustrated through a simple example. In the final section advantages and disadvantages in the SAMPO are noted and some research directions for the future are suggested.
Secrets of successful simulation projects
Authors: Stewart Robinson, Vinod Bhatia
Venue: Proceedings of the 27th conference on Winter simulation (1995)

Describes how a simulation project should be performed in order to ensure a successful outcome. This involves skills in both simulation and project management. The paper concentrates on the process of performing a simulation project rather than specific methods required during the course of a project. An overview of a simulation project is given before discussing in more detail the four main phases of a project: problem definition, model building and testing, experimentation and project completion.
Solving systems of nonlinear equations using the nonzero value of the topological degree
Authors: Michael N. Vrahatis
Venue: ACM Transactions on Mathematical Software (TOMS) (1988)

Two algorithms are described here for the numerical solution of a system of nonlinear equations F(X) = &THgr;, Q=0,0,&ldots;,0&isin; R , and F is a given continuous mapping of a region D in Rn into Rn . The first algorithm locates at least one root of the sy stem within n-dimensional polyhedron, using the non zero v alue of the topological degree of F at &thgr; relative to the polyhedron; th e second algorithm applies a new generalized bisection method in order to compute an approximate solution to the system. Teh size of the original n-dimensional polyhedron is arbitrary, and the method is globally convergent in a residual sense. These algorithms, in the various function evaluations, only make use of the algebraic sign of F and do not require computations of the topological degree. Moreover, they can be applied to nondifferentiable continuous functions F and do not involve derivatives of F or approximations of such derivatives.
Create!: an object-oriented IDE for discrete event simulation
Authors: Michael Rüger, Thomas Behlau
Venue: Proceedings of the 27th conference on Winter simulation (1995)

Create! is a graphical integrated development environment (IDE) for discrete event simulation. It features a complete modelling and simulation environment for end users working in a dedicated environment as well as an integrated development environment enabling advanced users or simulator developers to create extended or even new simulation environments. This paper presents major aspects of the Create!-environment and some tools built using it.
Developing a nonsymbolic phonetic notation for speech synthesis
Authors: Andrew Cohen
Venue: Computational Linguistics (1995)

The goal of the research presented here is to apply unsupervised neural network learning methods to some of the lower-level problems in speech synthesis currently performed by rule-based systems. The latter tend to be strongly influenced by notations developed by linguists (see figure 1 in Klatt (1987)), which were primarily devised to deal with written rather than spoken language. In general terms, what is needed in phonetics is a notation that captures information about ratios rather than absolute values, as is typically seen in biological systems. The notations derived here are based on an ordered pattern space that can be dealt with more easily by neural networks, and by systems involving a neural and symbolic component. Hence, the approach described here might also be useful in the design of a hybrid neural/symbolic system to operate in the speech synthesis domain.
A binary feedback scheme for congestion avoidance in computer networks with a connectionless network layer
Authors: K. K. Ramakrishnan, Raj Jain
Venue: ACM SIGCOMM Computer Communication Review (1995)

We propose a scheme for congestion avoidance in networks using a connectionless protocol at the network layer. The scheme uses feedback from the network to the users of the network. The interesting challenge for the scheme is to use a minimal amount of feedback (one bit in each packet) from the network to adjust the amount of traffic allowed into the network. The servers in the network detect congestion and set a congestion indication bit on packets flowing in the forward direction. The congestion indication is communicated back to the users through the transport level acknowledgement. The scheme is distributed, adapts to the dynamic state of the network, converges to the optimal operating point, is quite simple to implement, and has low overhead while operational. The scheme also addresses a very important aspect of fairness in the service provided to the various sources utilizing the network. The scheme attempts to maintain fairness in service provided to multiple sources. This paper presents the scheme and the analysis that went into the choice of the various decision mechanisms. We also address the performance of the scheme under transient changes in the network and for pathological conditions.
Simulation and analysis of business processes using GOLOG
Authors: Dimitris Plexousakis
Venue: Proceedings of conference on Organizational computing systems (1995)

This paper describes a novel approach to simulating and analyzing business processes using GOLOG, a high-level logic programming language suitable for defining complex behaviors and capable of simulating action execution. The language is based on an extended version of the situation calculus and incorporates a formal theory of action. Business processes can be viewed as actions (physical or perceptual) that affect the state of affairs or an agent's knowledge of this state. Using GOLOG, business processes can be specified, synthesized and tested for feasibility and consistency. The theoretical framework behind GOLOG includes a solution to the frame problem for perceptual and complex actions, as well as, a formal method for process analysis. The latter uses a solution to the ramification problem for proving the satisfaction or violation of constraints. In case this is not possible, the method proposes strengthenings to the processes' pre- and post-conditions, so that any implementation that meets the process specification, provably guarantees that constraints will not be violated. In this manner, business process reengineering can be assisted by a formal analysis and simulation tool for testing the consistency of the process model.
On the Sensitivity of Solution Components in Linear Systems of Equations
Authors: S. Chandrasekaran, I. C. F. Ipsen
Venue: SIAM Journal on Matrix Analysis and Applications (1995)

Expressions are presented for the errors in individual components of the solution to systems of linear equations and linear least squares problems. No assumptions about the structure or distribution of the perturbations are made. The resulting "componentwise condition numbers" measure the sensitivity of each solution component to perturbations. It is shown that any linear system has at least one solution component whose sensitivity to perturbations is proportional to the condition number of the matrix; but there may exist many components that are much better conditioned. Unless the perturbations are restricted, no norm-based relative error bound can predict the presence of well-conditioned components, so these componentwise condition numbers are essential. For the class of componentwise perturbations, necessary and sufficient conditions are given under which Skeel's condition numbers are informative, and it is shown that these conditions are similar to conditions where componentwise condition numbers are useful. Numerical experiments not only confirm that these circumstances do occur frequently, they also illustrate that for many classes of matrices the ill conditioning of the matrix is due to a few rows of the inverse only. This means that many of the solution components are computed more accurately than current analyses predict.
On the Order of Convergence of Preconditioned Nonlinear Conjugate Gradient Methods
Authors: M. Al-Baali, R. Fletcher
Venue: SIAM Journal on Scientific Computing (1996)

An analysis is given of preconditioned nonlinear conjugate gradient methods in which the preconditioning matrix is the exact Hessian matrix at each iteration (or a nearby matrix). It is shown that the order of convergence of certain preconditioned methods is less than that of Newton's method when exact line searches are used, and an example is given.
Vortex: an optimizing compiler for object-oriented languages
Authors: Jeffrey Dean, Greg DeFouw, David Grove, Vassily Litvinov, Craig Chambers
Venue: ACM SIGPLAN Notices (1996)

Previously, techniques such as class hierarchy analysis and profile-guided receiver class prediction have been demonstrated to greatly improve the performance of applications written in pure object-oriented languages, but the degree to which these results are transferable to applications written in hybrid languages has been unclear. In part to answer this question, we have developed the Vortex compiler infrastructure, a language-independent optimizing compiler for object-oriented languages, with front-ends for Cecil, C++, Java, and Modula-3. In this paper, we describe the Vortex compiler's intermediate language, internal structure, and optimization suite, and then we report the results of experiments assessing the effectiveness of different combinations of optimizations on sizable applications across these four languages. We characterize the benchmark programs in terms of a collection of static and dynamic metrics, intended to quantify aspects of the "object-orientedness" of a program.
Cilk: an efficient multithreaded runtime system
Authors: Robert D. Blumofe, Christopher F. Joerg, Bradley C. Kuszmaul, Charles E. Leiserson, Keith H. Randall, Yuli Zhou
Venue: ACM SIGPLAN Notices (1995)

Cilk (pronounced &ldquo;silk&rdquo;) is a C-based runtime system for multi-threaded parallel programming. In this paper, we document the efficiency of the Cilk work-stealing scheduler, both empirically and analytically. We show that on real and synthetic applications, the &ldquo;work&rdquo; and &ldquo;critical path&rdquo; of a Cilk computation can be used to accurately model performance. Consequently, a Cilk programmer can focus on reducing the work and critical path of his computation, insulated from load balancing and other runtime scheduling issues. We also prove that for the class of &ldquo;fully strict&rdquo; (well-structured) programs, the Cilk scheduler achieves space, time and communication bounds all within a constant factor of optimal.The Cilk runtime system currently runs on the Connection Machine CM5 MPP, the Intel Paragon MPP, the Silicon Graphics Power Challenge SMP, and the MIT Phish network of workstations. Applications written in Cilk include protein folding, graphic rendering, backtrack search, and the *Socrates chess program, which won third prize in the 1994 ACM International Computer Chess Championship.
Comments on "Line Digraph Iterations and Connectivity Analysis of de Bruijn and Kautz Graphs"
Authors: C. Padró, P. Morillo, M. A. Fiol
Venue: IEEE Transactions on Computers (1996)

The aim of this note is to present some counterexamples to the results in the paper by Du, Lyuu, and Hsu published in this Transactions [1].
A quasi-optimal cluster allocation strategy for parallel program execution in distributed systems using genetic algorithms
Authors: S. Esquivel, G. Leguizamon, R. Gallard
Venue: ACM SIGOPS Operating Systems Review (1995)

This paper shows an approach to find quasi-optimal solutions to the first optimization stage of parallel program tasks allocation problem, in an internet distributed system. The user initiates program execution from an arbitrary node in an arbitrary cluster, the parallel tasks comprising the program migrate to quasi-optimal clusters using an strategy that tries to minimize intercluster traffic of the parallel program execution.Genetic algorithms (GAs) [11] are used to provide a set of timely, quasi-optimal solutions.
The INCINERATE data model
Authors: H. V. Jagadish
Venue: ACM Transactions on Database Systems (TODS) (1995)

In this article, we present an extended relational algebra with universally or existentially quantified classes as attribute values. The proposed extension can greatly enhance the expressive power of relational systems, and significantly reduce the size of a database, at small additional computational cost. We also show how the proposed extensions can be built on top of a standard relational database system.