ppxscal/embedding_network huggingface dataset:
Be careful with don't cares
Authors: Daniel Brand, Reinaldo A. Bergamaschi, Leon Stok
Venue: Proceedings of the 1995 IEEE/ACM international conference on Computer-aided design (1995)

Abstract: It is commonly expected that any correct implementation can replace its specification inside a larger design without violating the correctness of the whole design. This property (called replaceability) is automatically satisfied in the absence of don't cares because "correctness" by definition implies that specification and implementation compute the identical function. However don't cares allow an implementation to compute a different function, and thus make it difficult to ensure replaceability. Whether this problem occurs depends on the exact meaning of "don't care" and the associated definition of "correctness". We will consider three meanings of "don't care" and for each give conditions under which correct implementations may replace their specifications.
A compilation of automatic differentiation tools presented at the 1995 international convention on industrial and applied mathematics, Hamburg
Authors: Chris Bischof, Fred Dilley
Venue: ACM SIGNUM Newsletter (1995)

This document was compiled for the minisymposium on automatic differentiation tools presented at the 1995 International Convention on Industrial and Applied Mathematics, Hamburg. The document was compiled by Chris Bischof and Fred Dilley of Argonne National Laboratory with contributions by Mike Bartholomew-Biggs, Stephen Brown, Alan Carle, Bruce Christianson, David Cowey, Frederic Eyssette, David M. Gay, Ralf Giering, Andreas Griewank, Jim Horwedel, Peyvand Khademi, K. Kubota, Andrew Mauer, Michael B. Monagan, John Pryce, John Reid, Andreas Rhodin, Nicole Rostaing-Schmidt, and Jean Utke.
Documentation standards in the undergraduate computer science curriculum
Authors: Renée A. McCauley, Ursula Jackson, Bill Manaris
Venue: ACM SIGCSE Bulletin (1996)

This paper focuses on documentation standards and their employment throughout the undergraduate computer science curriculum. Specifically, it presents the motivation for a set of well-defined documentation standards for programming-intensive computer science courses. Additionally, it discusses the establishment of standards addressing both the procedure- and object-oriented programming paradigms. Finally, it relates the authors' experiences in using such standards to teach many software engineering principles along with required concepts in the undergraduate computer science curriculum.
Complexity of Makanin's algorithm
Authors: Antoni Kościelski, Leszek Pacholski
Venue: Journal of the ACM (JACM) (1996)

The exponent of periodicity is an important factor in estimates of complexity of word-unification algorithms. We prove that the exponent of periodicity of a minimal solution of a word equation is of order 21.07d, where d is the length of the equation. We also give a lower bound 20.29d so our upper bound is almost optimal and exponentially better than the original bound (6d)22d4+ 2. Consequently, our result implies an exponential improvement of known upper bounds on complexity of word-unification algorithms.
Analysis and Optimization of Feedback Control Algorithms for Data Transfers in High-Speed Networks
Authors: Rauf Izmailov
Venue: SIAM Journal on Control and Optimization (1996)

Two linear feedback control algorithms for handling and preventing congestion in high-speed networks are proposed and analyzed. The fluid approximation model is described with a continuous-time system of delay-differential equations. The algorithms are asymptotically stable, and the transient processes are nonoscillatory. The control parameters are locally optimal (optimality is based on the asymptotic rate of convergence). The results of numerical experiments suggest that these parameters are globally optimal as well. The dependence of the quality of service on the duration of the control intervals is analyzed, and the performance of algorithms in a nonstationary environment is addressed.
CASE tools as collaborative support technologies
Authors: Iris Vessey, Ajay Paul Sravanapudi
Venue: Communications of the ACM (1995)

Since the inception of computers, the software industry has searched for dramatic solutions to its systems development problems. In the latter half of the 1980s and into the 1990s, the search has focused on automated software engineering (computer-assisted software engineering or CASE) tools (see, for example, [17]). Many in the software engineering field claim CASE tools will completely replace the software developer [15]. A more realistic view, however, is that such tools will aid systems developers in the process of specifying, designing, and constructing software systems.
Optimal mapping of sequences of data parallel tasks
Authors: Jaspal Subhlok, Gary Vondran
Venue: ACM SIGPLAN Notices (1995)

Many applications in a variety of domains including digital signal processing, image processing and computer vision are composed of a sequence of tasks that act on a stream of input data sets in a pipelined manner. Recent research has established that these applications are best mapped to a massively parallel machine by dividing the tasks into modules and assigning a subset of the available processors to each module. This paper addresses the problem of optimally mapping such applications onto a massively parallel machine. We formulate the problem of optimizing throughput in task pipelines and present two new solution algorithms. The formulation uses a general and realistic model for inter-task communication, takes memory constraints into account, and addresses the entire problem of mapping which includes clustering tasks into modules, assignment of processors to modules, and possible replication of modules. The first algorithm is based on dynamic programming and finds the optimal mapping of k tasks onto P processors in O(P4k2) time. We also present a heuristic algorithm that is linear in the number of processors and establish with theoretical and practical results that the solutions obtained are optimal in practical situations. The entire framework is implemented as an automatic mapping tool for the Fx parallelizing compiler for High Performance Fortran. We present experimental results that demonstrate the importance of choosing a good mapping and show that the methods presented yield efficient mappings and predict optimal performance accurately.
Fast Fourier Transform Accelerated Fast Multipole Algorithm
Authors: William D. Elliott, John A. Board,  Jr.
Venue: SIAM Journal on Scientific Computing (1996)

This paper describes an ${\cal O}(p^2 \log_2(p) N)$ implementation of the fast multipole algorithm (FMA) for $N$-body simulations. This method of computing the FMA is faster than the original, which is ${\cal O}(p^4N)$, where $p$ is the number of terms retained in the truncated multipole expansion representation of the potential field of a collection of charged particles. The $p$ term determines the accuracy of the calculation. The limiting ${\cal O}(p^4)$ computation in the original FMA is a convolution-like operation on a matrix of multipole coefficients. This paper describes the implementation details of a conversion of this limiting computation to linear convolution, which is then computed in the Fourier domain using the fast Fourier transform (FFT), based on a method originally outlined by Greengard and Rokhlin. In addition, this paper describes a new block decomposition of the multipole expansion data that provides numerical stability and efficient computation. The resulting ${\cal O}(p^2 \log_2(p))$ subroutine has a speedup of 2 on a sequential processor over the original method for $p=8$, and a speedup of 4 for $p=16$. The new subroutine vectorizes well and has a speedup of 3 on a vector processor at $p=8$ and a speedup of 6 at $p=16$.
A constant-time optimal parallel string-matching algorithm
Authors: Zvi Galil
Venue: Journal of the ACM (JACM) (1995)

Given a pattern string, we describe a way to preprocess it. We design a CRCW-PRAM constant time optimal parallel algorithm for finding all occurrences of the (preprocessed) pattern in any given text.
Stability of Symmetric Ill-Conditioned Systems Arising in Interior Methods for Constrained Optimization
Authors: Anders Forsgren, Philip E. Gill, Joseph R. Shinnerl
Venue: SIAM Journal on Matrix Analysis and Applications (1996)

Many interior methods for constrained optimization obtain a search direction as the solution of a symmetric linear system that becomes increasingly ill-conditioned as the solution is approached. In some cases, this ill-conditioning is characterized by a subset of the diagonal elements becoming large in magnitude. It has been shown that in this situation the solution can be computed accurately regardless of the size of the diagonal elements. In this paper we discuss the formulation of several interior methods that use symmetric diagonally ill-conditioned systems. It is shown that diagonal ill-conditioning may be characterized by the property of strict $t$-diagonal dominance, which generalizes the idea of diagonal dominance to matrices whose diagonals are substantially larger in magnitude than the off-diagonals. A perturbation analysis is presented that characterizes the sensitivity of $t$-diagonally dominant systems under a certain class of structured perturbations. Finally, we give a rounding-error analysis of the symmetric indefinite factorization when applied to $t$-diagonally dominant systems. This analysis resolves the (until now) open question of whether the class of perturbations used in the sensitivity analysis is representative of the rounding error made during the numerical solution of the barrier equations.
A Nonconvex Variational Problem with Constraints
Authors: Micol Amar, Carlo Mariconda
Venue: SIAM Journal on Control and Optimization (1995)

A multidimensional version of Liapunov-type theorems is proven. As an application, it is proven that, under proper hypothesis on the possibly nonconvex function $f$, the problem $\min \int_0^Tf(u'(t))\,dt$ on the subset of $W^{1,p}([0,T],\Bbb R^n)$ of those functions $u$ satisfying the prescribed boundary conditions and whose trajectory lies out of a prescribed open subset of $\Bbb R^n$ admits at least one solution.
P-Components and the Homogeneous Decomposition of Graphs
Authors: Beverly Jamison, Stephan Olariu
Venue: SIAM Journal on Discrete Mathematics (1995)

In this paper we introduce and investigate the notion of p-connectedness. As it turns out, this concept leads naturally to a unique tree representation for arbitrary graphs: the leaves of this tree are the p-connected components along with weak vertices, that is, vertices of the graph that belong to no p-connected component. We then show how to refine this decomposition to obtain a new decomposition that extends the well-known modular decomposition.
Process cost and value analysis
Authors: Brian A. Nejmeh
Venue: Communications of the ACM (1995)

After years of pursuing fragments of a solution to the challenges of software engineering, including the development of methods, tools, and the like, the software engineering community has come to realize that over-emphasizing any one of these areas to the exclusion of others is incorrect. The community now recognizes that well-defined and well-supported processes are the critical issue for producing high-quality software systems on-time and within budget.
Balancing histogram optimality and practicality for query result size estimation
Authors: Yannis E. Ioannidis, Viswanath Poosala
Venue: Proceedings of the 1995 ACM SIGMOD international conference on Management of data (1995)

Many current database systems use histograms to approximate the frequency distribution of values in the attributes of relations and based on them estimate query result sizes and access plan costs. In choosing among the various histograms, one has to balance between two conflicting goals: optimality, so that generated estimates have the least error, and practicality, so that histograms can be constructed and maintained efficiently. In this paper, we present both theoretical and experimental results on several issues related to this trade-off. Our overall conclusion is that the most effective approach is to focus on the class of histograms that accurately maintain the frequencies of a few attribute values and assume the uniform distribution for the rest, and choose for each relation the histogram in that class that is optimal for a self-join query.
$H^\infty$ Optimal Sensitivity for a Class of Infinite-Dimensional Systems
Authors: Hong Yang
Venue: SIAM Journal on Control and Optimization (1995)

The computation of the ${\bf H}^\infty$ optimal weighted pure and mixed sensitivities for a class of infinite-dimensional systems is studied by characterizing certain wandering subspaces of some related Krein spaces. The new characterizations can be used to obtain explicit bases for those subspaces. Explicit formulas for the optimal sensitivity for some infinite-dimensional systems can be obtained from these bases. The new characterizations can also be used to obtain fast algorithms for computing the ${\bf H}^\infty$ optimal performance for pure and mixed sensitivity problems. The results are applied to obtain an explicit optimal sensitivity formula for a class of infinite-dimensional systems that generalizes a known result.
Empirical measurements of overheads in conservative asynchronous simulations
Authors: Mary L. Bailey, Michael A. Pagels
Venue: ACM Transactions on Modeling and Computer Simulation (TOMACS) (1994)

In order to make formal and analytic models more realistic, overheads which were previously ignored or vastly simplified must be included. We consider the feasibility of characterizing the overheads in conservative asynchronous simulations for such models, and we focus on a single communication structure (i.e., meshes) and use both multicomputer programs and a queueing network as example applications. We find that the two most important issues for modeling are to understand how to estimate the time spent in sending null messages and how to account for the resulting overhead due to the input waiting rule. For null messages, we estimate both the number of messages sent as well as the cost per null message. The number of messages sent can often be estimated by the application, although irregularities in communication structure and edge effects in communication can affect these estimates. A constant is valid as a first-order approximation for the time per null message, but there are secondary factors that one may wish to model, such as load balancing and communication irregularities. The overhead attributable to the input waiting rule depends on several factors: communication structure, communication frequency, and processor load balancing. Irregularity in any of these dimensions can adversely affect the performance of the conservative strategy. It appears feasible to use the factors contributing to the overheads (i.e. context switch costs; null-message costs; percentage of looping due to the conservative synchronization) in a formal model to estimate the cost of the conservative overheads.
On Eigenvalue Estimates for Block Incomplete Factorization Methods
Authors: O. Axelsson, H. Lu
Venue: SIAM Journal on Matrix Analysis and Applications (1995)

Eigenvalue estimates of block incomplete preconditioners are considered. We investigate how the block diagonal entries and off-block diagonal entries influence the bounds of all eigenvalues. The results presented here improve and unify some previous results. We generalize the well-known inequality that the spectral radius is bounded by the trace for symmetric positive semidefinite matrices to block form. Some of the methods can also be useful to estimate lower bounds of block incomplete preconditioners.
Bottom in the imperative world
Authors: Apostolos Syropoulos, Alexandros Karakos
Venue: ACM SIGPLAN Notices (1995)

Bottom is used in functional programming languages to denote abnormal situations. We propose the incorporation of this value in any existing imperative language. We show how this can be done and finally what are the benefits of the bottom incorporation in any imperative language.Covariant deep subtyping has always been viewed as a way to narrow the range of a component in subtypes. In this paper, however, we will see covariant deep subtyping in a new light---a way to clarify a vague but fixed range of a component in subclasses. We will also examine such concepts as class substitution, generic calss by BETA/Cluster, and a number of theoretic approaches in relation to covariant deep subtyping.
A close look at the IFO data model
Authors: Magdy S. Hanna
Venue: ACM SIGMOD Record (1995)

The IFO data model was proposed by Abiteboul and Hull [Abiteboul 87] as a formalized semantic database model. It has been claimed by the authors that the model subsumes the Relational model [Codd 70], the Entity-Relationship model [Chen 76], the Functional Data Model [Kerschberg 76] and virtually all of the structured aspects of the Semantic Data Model [Hammer 81], the INSYDE Model [King 85], and the Extended Semantic Hierarchy Model [Brodie 84].This paper examines the IFO data model as presented in [Abiteboul 87], compares it to other models, and thus concludes that the IFO data model is actually a subset of the Semantic Data Model proposed by Hammer in [Hammer 81]. The paper also shows that the IFO data model has failed to support concepts that are essential to both the E-R model and the Semantic Data Model which are claimed to be subsumed by the IFO model.Section 2 discusses the three IFO constructs, objects, fragments, and relationships. The mapping of these constructs to constructs in the Semantic Data Model is established as an informal proof of the result that the IFO model is subsumed by the SDM.Section 3 lists constructs supported by the Entity-Relationship model [Chen 76, Teorey 86] as will as constructs supported by SDM [Hammer 81]that the IFO data model fails to support.
ACM Multimedia '94 conference workshop on multimedia database management systems
Authors: Bruce Berra, Kingsley Nwosu, Bhavani Thuraisingham
Venue: ACM SIGMOD Record (1995)

This paper describes the ACM Multimedia '94 Conference Workshop on Multimedia Database Management Systems held on 21 October 1994 in San Francisco, California. The workshop consisted of four sessions: designing multimedia database management systems, video and continuous media service, multimedia storage and retrieval management, and miscellaneous topics in multimedia data management. The workshop concluded with a discussion session on directions for multimedia database management. Twenty-eight participants from U.S.A., U.K., Germany, Norway, and Egypt attended the workshop.
On-line extraction of SCSI disk drive parameters
Authors: Bruce L. Worthington, Gregory R. Ganger, Yale N. Patt, John Wilkes
Venue: Proceedings of the 1995 ACM SIGMETRICS joint international conference on Measurement and modeling of computer systems (1995)

Sophisticated disk scheduling algorithms require accurate, detailed disk drive specifications, including data about mechanical delays, on-board caching and prefetching algorithms, command and protocol overheads, and logical-to-physical block mappings. Comprehensive disk models used in storage subsystem design require similar levels of detail. We describe a suite of general-purpose algorithms and techniques for acquiring the necessary information from a SCSI disk drive. Using only the ANSI-standard interface, we demonstrate how the important parameter values of a modern SCSI drive can be determined accurately and efficiently.
Getting it across: layout issues for kiosk systems
Authors: Jan Borchers, Oliver Deussen, Clemens Knörzer
Venue: ACM SIGCHI Bulletin (1995)

A clear and appealing screen layout is crucial to the success of on-line kiosk systems, public terminals that are connected to a network. This paper addresses the problem of developing such a layout, and provides several guidelines, drawn from traditional typography and Gestalt psychology as well as from hypertext authoring, and human-computer interaction. To identify how a kiosk system's primary task influences optimal layout, kiosk systems are classified into four basic types. The usability of HTML (Hypertext Markup Language) 2.0 and 3.0 to write documents for these systems is discussed, and some alternative existing environments are presented.
The incrementor: a graphical technique for manipulating parameters
Authors: Sanford Ressler
Venue: ACM Transactions on Graphics (TOG) (1987)

Description: The incrementor is a visually compact, flexible, and consistent mechanism for modifying the variables presented to the user. A locator (i.e., mouse) with two buttons is the required input device. The names of the variables appear in the center of one or two pairs of arrows, and the value of the variable appears just below the right arrow and to the left of the up arrow (Figures 1 and 2).
Semi-proximity continuous functions in digital images
Authors: Longin Latecki, Frank Prokop
Venue: Pattern Recognition Letters (1995)

Starting with the intuitive concept of ''nearness'' as a binary relation, semi-proximity spaces (sp-spaces) are defined. The restrictions on semi-proximity spaces are weaker than on topological proximity spaces. Thus, semi-proximity spaces generalize classical topological spaces. Moreover, it is possible to describe all digital pictures used in computer vision and computer graphics as non-trivial semi-proximity spaces. which is not possible in classical topology. Therefore, we use semi-proximity spaces to establish a formal relationship between the ''topological'' concepts of digital image processing and their continuous counterparts in @?^n. Especially interesting are continuous functions in semi-proximity spaces which are called ''semi-proximity'' continuous functions. They can be used for characterizing well-behaved operations on digital images such as thinning. It will be shown that the deletion of a simple point can be treated as a semi-proximity continuous function. These properties and the fact that a variety of nearness relations can be defined on digital pictures indicate that semi-proximity continuous functions are a useful tool in the difficult task of shape description.
Analysis of a QR Algorithm for Computing Singular Values
Authors: S. Chandrasekaran, I. C. F. Ipsen
Venue: SIAM Journal on Matrix Analysis and Applications (1995)

We extend the Golub--Kahan algorithm for computing the singular value decomposition of bidiagonal matrices to triangular matrices $R$. Our algorithm avoids the explicit formation of $R^TR$ or $RR^T$. We derive a relation between left and right singular vectors of triangular matrices and use it to prove monotonic convergence of singular values and singular vectors. The convergence rate for singular values equals the square of the convergence rate for singular vectors. The convergence behaviour explains the occurrence of deflation in the interior of the matrix. We analyse the relationship between our algorithm and rank-revealing QR and URV decompositions. As a consequence, we obtain an algorithm for computing the URV decomposition, as well as a divide-and-conquer algorithm that computes singular values of dense matrices and may be beneficial on a parallel architecture. Our perturbation result for the smallest singular values of a triangular matrix is stronger than the traditional results because it guarantees high relative accuracy in the smallest singular values after an off-diagonal block of the matrix has been set to zero.