ppxscal/embedding_network huggingface dataset:
The Sparse Basis Problem and Multilinear Algebra
Authors: Richard A. Brualdi, Shmuel Friedland, Alex Pothen
Venue: SIAM Journal on Matrix Analysis and Applications (1995)

Let $A$ be a $k \by n$ underdetermined matrix. The sparse basis problem for the row space $W$ of $A$ is to find a basis of $W$ with the fewest number of nonzeros. Suppose that all the entries of $A$ are nonzero, and that they are algebraically independent over the rational number field. Then every nonzero vector in $W$ has at least $n-k+1$ nonzero entries. Those vectors in $W$ with exactly $n-k+1$ nonzero entries are the elementary vectors of $W$. A simple combinatorial condition that is both necessary and sufficient for a set of $k$ elementary vectors of $W$ to form a basis of $W$ is presented here. A similar result holds for the null space of $A$ where the elementary vectors now have exactly $k+1$ nonzero entries. These results follow from a theorem about nonzero minors of order $m$ of the $(m-1)$st compound of an $m \by n$ matrix with algebraically independent entries, which is proved using multilinear algebra techniques. This combinatorial condition for linear independence is a first step towards the design of algorithms that compute sparse bases for the row and null space without imposing artificial structure constraints to ensure linear independence.
SIMD machines: do they have a significant future?
Authors: Behrooz Parhami
Venue: ACM SIGARCH Computer Architecture News (1995)

I volunteered to write this report during the SIMD panel session held on 2/9/95 at Frontiers '95. All panelists cooperated by sending me their transparency masters. A draft report was prepared based on these transparency masters, position statements published in the Frontiers '95 proceedings on pp. 466-469, and my own notes. The draft was e-mailed on 3/17/95 to the panel organizer/moderator and the panelists for their comments. This final version of the report is based on comments and markups received through 3/31/95. I have drawn from the panelists' ideas freely, using quotation marks only when including their statements verbatim.The panel consisted of both academic and industry experts in the field of massively parallel systems (see the table below). All but Tim Bridges, who is currently involved in a large-scale software development project for the MasPar MP-2 SIMD architecture, have built working SIMD machines. The vast practical experience of the panel was quite evident in the insightful presentations and interactions. It is indeed a privilege for me to have worked on this report.
The mathematical basis and a prototype implementation of a new polynomial rootfinder with quadratic convergence
Authors: T. E. Hull, R. Mathon
Venue: ACM Transactions on Mathematical Software (TOMS) (1996)

Formulas developed originally by Weierstrass have been used since the 1960s by many others for the simultaneous determination of all the roots of a polynomial. Convergence to simple roots is quadratic, but individual approximations to a multiple root converge only linearly. However, it is shown here that the mean of such individual approximations converges quadratically to that root. This result, along with some detail about the behavior of such approximations in the neighborhood of the multiple root, suggests a new approach to the design of polynomial rootfinders. It should also be noted that the technique is well suited to take advantage of a parallel environment. This article first provides the relevant mathematical results: a short derivation of the formulas, convergence proofs, an indication of the behavior near a multiple root, and some error bounds. It then provides the outline of an algorithm based on these results, along with some graphical and numerical results to illustrate the major theoretical points. Finally, a new program based on this algorithm, but with a more efficient way of choosing starting values, is described and then compared with corresponding programs from IMSL and NAG with good results. This program is available from Mathon (combin@cs.utoronto.ca)..
Replication: DB2, Oracle, or Sybase?
Authors: Doug Stacey
Venue: ACM SIGMOD Record (1995)

Is replication salvation or the devil in disguise? Here's what three implementations tell us
Bayesian networks
Authors: David Heckerman, Michael P. Wellman
Venue: Communications of the ACM (1995)

This brief tutorial on Bayesian networks serves to introduce readers to some of the concepts, terminology, and notation employed by articles in this special section. In a Bayesian network, a variable takes on values from a collection of mutually exclusive and collective exhaustive states. A variable may be discrete, having a finite or countable number of states, or it may be continuous. Often the choice of states itself presents an interesting modeling question. For example, in a system for troubleshooting a problem with printing, we may choose to model the variable &ldquo;print output&rdquo; with two states&mdash;&ldquo;present&rdquo; and &ldquo;absent&rdquo;&mdash;or we may want to model the variable with finer distinctions such as &ldquo;absent,&rdquo; &ldquo;blurred ,&rdquo; &ldquo;cut off,&rdquo; and &ldquo;ok.&rdquo;
Reducing disk power consumption in a portable computer
Authors: William F. Klostermeyer, Kankanahalli Srinivas
Venue: ACM SIGOPS Operating Systems Review (1995)

The problem of minimizing disk power consumption in portable personal computers is studied. Two online algorithms for determining when to stop spinning a disk are presented and analyzed using competitive analysis techniques.
Architecture of centralized field-configurable memory
Authors: Steven J. E. Wilton, Jonathan Rose, Zvonko G. Vranesic
Venue: Proceedings of the 1995 ACM third international symposium on Field-programmable gate arrays (1995)

As the capacities of FPGAs grow, it becomes feasible to implement the memory portions of systems directly on an FPGA together with logic. We believe that such an FPGA must contain specialized architectural support in order to implement memories efficiently. The key feature of such architectural support is that it must be flexible enough to accommodate many different memory shapes (widths and depths) as well as allowing different numbers of independently-addressed memory blocks. This paper describes a family of centralized Field-Configurable Memory architectures which consist of a number of memory arrays and dedicated mapping blocks to combine these arrays. We also present a method for comparing these architectures, and use this method to examine the tradeoffs involved in choosing the array size and mapping block capabilities.
The interaction of parallel and sequential workloads on a network of workstations
Authors: Remzi H. Arpaci, Andrea C. Dusseau, Amin M. Vahdat, Lok T. Liu, Thomas E. Anderson, David A. Patterson
Venue: Proceedings of the 1995 ACM SIGMETRICS joint international conference on Measurement and modeling of computer systems (1995)

This paper examines the plausibility of using a network of workstations (NOW) for a mixture of parallel and sequential jobs. Through simulations, our study examines issues that arise when combining these two workloads on a single platform. Starting from a dedicated NOW just for parallel programs, we incrementally relax uniprogramming restrictions until we have a multi-programmed, multi-user NOW for both interactive sequential users and parallel programs. We show that a number of issues associated with the distributed NOW environment (e.g., daemon activity, coscheduling skew) can have a small but noticeable effect on parallel program performance. We also find that efficient migration to idle workstations is necessary to maintain acceptable parallel application performance. Furthermore, we present a methodology for deriving an optimal delay time for recruiting idle machines for use by parallel programs; this recruitment threshold was just 3 minutes for the research cluster we measured. Finally, we quantify the effects of the additional parallel load upon interactive users by keeping track of the potential number of user delays in our simulations. When we limit the maximum number of delays per user, we can still maintain acceptable parallel program performance. In summary, we find that for our workloads a 2:1 rule applies: a NOW cluster of approximately 60 machines can sustain a 32-node parallel workload in addition to the sequential load placed upon it by interactive users.
Working smarter when developing linear simulation metamodels
Authors: Michael K. Taylor, Paul F. Auclair, Edward F. Mykytka
Venue: Proceedings of the 27th conference on Winter simulation (1995)

We propose that proper metamodel specification is far more important than the level of simulation effort used in developing a metamodel to estimate the expected response of a given system or simulation. In particular, M/M/k queues with various configurations of arrival rate, service rate, and number of servers were simulated using different levels of simulation effort. The average queue length for each configuration was computed, and then two different metamodels were fit to the simulation data. Analysis of the residuals from the fitted metamodels indicates that metamodel specification has a significant effect on the statistical quality of the estimated expected queue length while the level of simulation effort used in fitting the metamodel has virtually no such effect.
The Internet's World Wide Web and the simulation community: a surfing lesson for beginners
Authors: Peter D. Welch, Josephine van der Hoeven
Venue: Proceedings of the 27th conference on Winter simulation (1995)

The World Wide Web (WWW or the Web) is the fastest growing service of the Internet. The paper covers a portion of the corresponding conference talk. The talk provides an overview of the Internet, the World Wide Web, and the College on Simulation of INFORMS Home Page. The talk is either online or the simulation of an online session (surfing) of the Web. It hopefully provides the background and the incentive to turn the audience into WWW enthusiasts. No knowledge of the Internet or the WWW is assumed.
A type-based compiler for standard ML
Authors: Zhong Shao, Andrew W. Appel
Venue: Proceedings of the ACM SIGPLAN 1995 conference on Programming language design and implementation (1995)

Compile-time type information should be valuable in efficient compilation of statically typed functional languages such as Standard ML. But how should type-directed compilation work in real compilers, and how much performance gain will type-based optimizations yield? In order to support more efficient data representations and gain more experience about type-directed compilation, we have implemented a new type-based middle end and back end for the Standard ML of New Jersey compiler. We describe the basic design of the new compiler, identify a number of practical issues, and then compare the performance of our new compiler with the old non-type-based compiler. Our measurement shows that a combination of several simple type-based optimizations reduces heap allocation by 36%; and improves the already-efficient code generated by the old non-type-based compiler by about 19% on a DECstation 500.
Experiments in Curvature-Based Segmentation of Range Data
Authors: Emanuele Trucco, Robert B. Fisher
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1995)

This paper focuses on the experimental evaluation of a range image segmentation system which partitions range data into homogeneous surface patches using estimates of the sign of the mean and Gaussian curvatures. We report the results of an extensive testing program aimed at investigating the behavior of important experimental parameters such as the probability of correct classification and the accuracy of curvature estimates, measured over variations of significant segmentation variables. Evaluation methods in computer vision are often unstructured and subjective: this paper contributes a useful example of extensive experimental assessment of surface-based range segmentation.
The target switch algorithm: a constructive learning procedure for feed-forward neural networks
Authors: Colin Campbell, C. Perez Vicente
Venue: Neural Computation (1995)

We propose an efficient procedure for constructing and training a feedforward neural network. The network can perform binary classification for binary or analogue input data. We show that the procedure can also be used to construct feedforward neural networks with binary-valued weights. Neural networks with binary-valued weights are potentially straightforward to implement using microelectronic or optical devices and they can also exhibit good generalization.
An infrastructure for cooperative applications based on conventional database transactions
Authors: N. Ritter
Venue: ACM SIGOIS Bulletin (1995)

'Computer-Supported Cooperative Work' (CSCW) is a young, interdisciplinary research area considering applications with strong demands on multiple fields of computer technology, e.g., distributed systems and networks, or multi-media systems. In this paper, we will be focusing on the information-sharing aspect and the corresponding activity-control aspect. Employing database systems for the management of shared data means dealing with conventional transactions. Crucial issues of the classical transaction concept are the isolated execution and the underlying notion of consistency. Whereas consistency support is necessary for any multi-user application, strict isolation seems to contradict the cooperation issue (release of preliminary data). As a consequence, the transaction concept plays a key role due to consistency management, but cooperation control must be supported by additional facilities. Therefore, we exploit the classical transaction as the basic operational unit in the infrastructure we propose for cooperative applications. Transactions are well suited for the execution of the elementary actions into which the work of a cooperating user can be decomposed. Beside these elementary actions, further types of activities can be observed in cooperative work arrangements. In order to give a comprehensive activity support, our infrastructure provides several abstractional layers: classical transactions, version manipulations, tool invocations, workflow executions and explicit cooperation control actions. Multiple possibilities of interplay between these layers make this infrastructure feasible to different classes of cooperative applications.
Trigonometric Collocation Methods with Product Integration for Boundary Integral Equations on Closed Curves
Authors: J. Saranen, G. Vainkko
Venue: SIAM Journal on Numerical Analysis (1996)

Considering boundary integral equations on smooth closed curves the product integration methods have turned out to be very efficient to define fully discrete schemes with a high convergence rate. Here we give a general approach to product integration methods in connection with the trigonometric collocation. The discretization scheme has arbitrarily high convergence rate, even exponential if the solution and the curve are analytic. Applications and numerical experiments confirming our theoretical results are discussed.
Compiler and hardware support for cache coherence in large-scale multiprocessors: design considerations and performance study
Authors: Lynn Choi, Pen-Chung Yew
Venue: Proceedings of the 23rd annual international symposium on Computer architecture (1996)

In this paper, we study a hardware-supported, compiler directed (HSCD) cache coherence scheme, which can be implemented on a large-scale multiprocessor using off-the-shelf microprocessors, such as the Cray T3D. It can be adapted to various cache organizations, including multi-word cache lines and byte-addressable architectures. Several system related issues, including critical sections, inter-thread communication, and task migration have also been addressed. The cost of the required hardware support is small and proportional to the cache size. The necessary compiler algorithms, including intra- and interprocedural array data-flow analysis, have been implemented on the Polaris compiler [17].From our simulation study using the Perfect Club benchmarks, we found that, in spite of the conservative analysis made by the compiler, the performance of the proposed HSCD scheme can be comparable to that of a full-map hardware directory scheme. With its comparable performance and reduced hardware cost, the scheme can be a viable alternative for large-scale multiprocessors, such as the Cray T3D, that rely on users to maintain data coherence.
The integration of computing and routine work
Authors: Les Gasser
Venue: ACM Transactions on Information Systems (TOIS) (1986)

Most computing serves as a resource or tool to support other work: performing complex analyses for engineering projects, preparing documents, or sending electronic mail using office automation equipment, etc. To improve the character, quality, and ease of computing work, we must understand how automated systems actually are integrated into the work they support. How do people actually adapt to computing as a resource? How do they deal with the unreliability in hardware, software, or operations; data inaccuracy; system changes; poor documentation; inappropriate designs; etc.; which are present in almost every computing milieu, even where computing is widely used and considered highly successful? This paper presents some results of a detailed empirical study of routine computer use in several organizations. We present a theoretical account of computing work and use it to explain a number of observed phenomena, such as: How people knowingly use &ldquo;false&rdquo; data to obtain desired analytical results by tricking their systems. How organizations come to rely upon complex, critical computer systems despite significant, recurrent, known errors and inaccurate data. How people work around inadequate computing systems by using manual or duplicate systems, rather than changing their systems via maintenance or enhancement. In addition, the framework for analyzing computing and routine work presented here proves useful for representing and reasoning about activity in multiactor systems in general, and in understanding how better to integrate organizations of people and computers in which work is coordinated.
Query execution techniques for caching expensive methods
Authors: Joseph M. Hellerstein, Jeffrey F. Naughton
Venue: ACM SIGMOD Record (1996)

Object-Relational and Object-Oriented DBMSs allow users to invoke time-consuming ("expensive") methods in their queries. When queries containing these expensive methods are run on data with duplicate values, time is wasted redundantly computing methods on the same value. This problem has been studied in the context of programming languages, where "memoization" is the standard solution. In the database literature, sorting has been proposed to deal with this problem. We compare these approaches along with a third solution, a variant of unary hybrid hashing which we call Hybrid Cache. We demonstrate that Hybrid Cache always dominates memoization, and significantly outperforms sorting in many instances. This provides new insights into the tradeoff between hashing and sorting for unary operations. Additionally, our Hybrid Cache algorithm includes some new optimization for unary hybrid hashing, which can be used for other applications such as grouping and duplicate elimination. We conclude with a discussion of techniques for caching multiple expensive methods in a single query, and raise some new optimization problems in choosing caching techniques.
Logic synthesis for look-up table based FPGAs using functional decomposition and support minimization
Authors: Hiroshi Sawada, Takayuki Suyama, Akira Nagoya
Venue: Proceedings of the 1995 IEEE/ACM international conference on Computer-aided design (1995)

This paper presents a logic synthesis method for look-up table (LUT) based field programmable gate arrays (FPGAs). We determine functions to be mapped to LUTs by functional decomposition. We use not only disjunctive decomposition but also nondisjunctive decomposition. Furthermore, we propose a new Boolean resubstitution technique customized for an LUT network synthesis. Resubstitution is used to determine whether an existing function is useful to realize another function; thus, we can share the common function among two or more functions. The Boolean resubstitution is effectively carried out by solving a support minimization problem for an incompletely specified function. We can also handle satisfiability don't cares of an LUT network using the technique.
Information technology innovations: a classification by IT locus of impact and research approach
Authors: Mary B. Prescott, Sue A. Conger
Venue: ACM SIGMIS Database (1995)

Research based on diffusion of innovation (DOI) theory investigates the evaluation, adoption, and implementation of innovations. Gaining understanding is difficult when tracing results on a study-by-study basis. To remove some of the barriers to comparison of results, we distinguish between innovations according to their locus of impact (IS unit, intra- or inter-organizational) and between studies according to research approach (factor or stage).A representative sample of 70 information technology (IT) related DOI research studies published by IT researchers over the last decade is evaluated using this classification scheme. From the analysis, it appears that the classification scheme may be used to provide a clearer understanding of IT innovation diffusion.Traditional DOI theory appears to be most applicable to ITs which have an intra-organizational locus of impact. ITs with an information system (IS) unit locus of impact appear to require less organizational support, and their extent of implementation appears to be related to nontraditional innovation characteristics such as functionality and efficiency. Inter-organizational locus of impact IT innovations, however, appear to be more affected by contextual and environmental variables, and their differences may be better explained by economic influence or critical mass theories.
Analyzing Regression Test Selection Techniques
Authors: Gregg Rothermel, Mary Jean Harrold
Venue: IEEE Transactions on Software Engineering (1996)

Regression testing is a necessary but expensive maintenance activity aimed at showing that code has not been adversely affected by changes. Regression test selection techniques reuse tests from an existing test suite to test a modified program. Many regression test selection techniques have been proposed; however, it is difficult to compare and evaluate these techniques because they have different goals. This paper outlines the issues relevant to regression test selection techniques, and uses these issues as the basis for a framework within which to evaluate the techniques. We illustrate the application of our framework by using it to evaluate existing regression test selection techniques. The evaluation reveals the strengths and weaknesses of existing techniques, and highlights some problems that future work in this area should address.
Quasi-Varieties, Congruences, and Generalized Dowling Lattices
Authors: Andreas Blass
Venue: Journal of Algebraic Combinatorics: An International Journal (1995)

Dowling lattices and their generalizations introduced by Hanlon are interpreted as lattices of congruences associated to certain quasi-varieties of sets with group actions. This interpretation leads, by a simple application of M&ouml;bius inversion, to polynomial identities which specialize to Hanlon's evaluation of the characteristic polynomials of generalized Dowling lattices. Analogous results are obtained for a few other quasi-varieties.