ppxscal/embedding_network huggingface dataset:
Centroidal Voronoi Tessellations: Applications and Algorithms
Authors: Qiang Du, Vance Faber, Max Gunzburger
Venue: SIAM Review (1999)

A centroidal Voronoi tessellation is a Voronoi tessellation whose generating points are the centroids (centers of mass) of the corresponding Voronoi regions. We give some applications of such tessellations to problems in image compression, quadrature, finite difference methods, distribution of resources, cellular biology, statistics, and the territorial behavior of animals. We discuss methods for computing these tessellations, provide some analyses concerning both the tessellations and the methods for their determination, and, finally, present the results of some numerical experiments.
A visual medium for programmatic control of interactive applications
Authors: Luke S. Zettlemoyer, Robert St. Amant
Venue: Proceedings of the SIGCHI conference on Human factors in computing systems: the CHI is the limit (1999)

The VisMap system provides for visual manipulation of arbitrary off-the-shelf applications, through an applications graphical user interface. VisMaps API-independent control has advantages for tasks that can benefit from direct access to the functions of the user interface. We describe the design goals and architecture of the system, and we discuss two applications, a user-controlled visual scripting program and an autonomous solitaire-playing program, which together demonstrate some of the capabilities and limitations of the approach.
A multi-agent system for computer science education
Authors: Hongchi Shi, Yi Shang, Su-Shing Chen
Venue: ACM SIGCSE Bulletin (2000)

In this paper, we present a multi-agent system for supporting student-centered, self-paced, and highly interactive learning in undergraduate computer science education. The system is based on a hybrid problem-based and case-based learning model, for both creative problem solving and mechanical experience simulation. It aims at enhancing the effectiveness of the undergraduate learning experience in computer science. Implemented using the prevalent Internet, Web, and digital library technologies, the system adopts an open architecture design and targets at large-scale, distributed operations. In the initial implementation of the system, a number of prototypes using different Java-based software environments have been developed. They offer tradeoffs in system performance and design complexity.
An Average L2 Discrepancy for Number-Theoretic Rules
Authors: Stephen Joe
Venue: SIAM Journal on Numerical Analysis (1999)

One measure of the "goodness" of a quadrature rule Q for approximating integrals over the unit hypercube is the L2 discrepancy D(Q). For number-theoretic rules of prime order n we derive an expression for the average of D2(Q). Having this average makes it possible to compare the potential of number-theoretic rules for nonperiodic integrands with equal-weight quadrature rules in which the points are independent and uniformly distributed. The numerical results presented suggest that number-theoretic rules are competitive with such rules (as measured by the average L2 discrepancy) when the dimension is not more than about 18. The expression obtained for the average is not fully in closed form as it contains certain sums related to Dedekind sums for which no closed forms are available. An efficient algorithm for calculating Dedekind sums allows the average to be calculated in O(n log n) operations.
Model-checking continuous-time Markov chains
Authors: Adnan Aziz, Kumud Sanwal, Vigyan Singhal, Robert Brayton
Venue: ACM Transactions on Computational Logic (TOCL) (2000)

We present a logical formalism for expressing properties of continuous-time Markov chains. The semantics for such properties arise as a natural extension of previous work on discrete-time Markov chains to continuous time. The major result is that the verification problem is decidable; this is shown using results in algebraic and transcendental number theory.
k-set agreement with limited accuracy failure detectors
Authors: Achour Mostéfaoui, Michel Raynal
Venue: Proceedings of the nineteenth annual ACM symposium on Principles of distributed computing (2000)

Let the scope of the accuracy property of an unreliable failure detector be the number x of processes that may not suspect a correct process. The scope notion gives rise to new classes of failure detectors among which we consider Sx and &diam;Sx in this paper (Usual failure detectors consider an implicit scope equal to n, the total number of processes). The k-set agreement problem generalizes the consensus problem: each correct process has to decide a value in such a way that a decided value is a proposed value, and the number of decided values is bounded by k. There exist protocols that solve this problem in asynchronous distributed systems when &fnof; < k (where &fnof; is the maximum number of processes that may crash). Moreover, it has been shown that there is no solution in those systems when &fnof; &ge; k. The paper considers asynchronous distributed systems equipped with limited scope accuracy failure detectors. It studies conditions on n, &fnof;, k and x that allow to solve the k-set agreement problem in those systems and presents two protocols. The first protocol solves the k-set agreement in asynchronous distributed systems augmented with a failure detector of the class Sx. It requires &fnof; < k + x - 1. The second protocol works with any failure detector of the class &diam;Sx. It actually defines a family of protocols. This family allows to solve the k-set agreement problem when &fnof; < max(k, max1&le;&agr;&le;k(min(n - &agr;&lfloor;n/(&agr; + 1)&rfloor;, &agr; +x - 1))). We conjecture that, when &fnof; &ge; k, these conditions are necessary to solve the k-set agreement problem in asynchronous distributed systems equipped with failure detectors &egr; Sx or &diam;Sx, respectively.
Orlik-Solomon Algebras and Tutte Polynomials
Authors: Carrie J. Eschenbrenner, Michael J. Falk
Venue: Journal of Algebraic Combinatorics: An International Journal (1999)

The OS algebra A of a matroid M is a graded algebra related to the Whitney homology of the lattice of flats of M. In case M is the underlying matroid of a hyperplane arrangement {\cal A} in{\bb {C}}^r , A is isomorphic to the cohomology algebra of the complement {\bb {C}}^r \{\bigcup}\,{\cal{A}}. Few examples are known of pairs of arrangements with non-isomorphic matroids but isomorphic OS algebras. In all known examples, the Tutte polynomials are identical, and the complements are homotopy equivalent but not homeomorphic.We construct, for any given simple matroid M_0, a pair of infinite families of matroids M and M&prime;_n, n &ge; 1, each containing M_0 as a submatroid, in which corresponding pairs have isomorphic OS algebras. If the seed matroid M_0 is connected, then M and M&prime;_n have different Tutte polynomials. As a consequence of the construction, we obtain, for any m, m different matroids with isomorphic OS algebras. Suppose one is given a pair of central complex hyperplane arrangements {\cal {A}}_0 and{\cal {A}}_1 . Let {\cal {S}} denote the arrangement consisting of the hyperplane &lcub;0&rcub; in {\bb {C}}^1 . We define the parallel connection P({\cal{A}}_0, {\cal{A}}_1 ), an arrangement realizing the parallel connection of the underlying matroids, and show that the direct sums {\cal{A}}_0 \oplus {\cal{A}}_1 and<?TeX="{\cal S} \oplus P({\cal A}_0,{\cal A}_1)"> have diffeomorphic complements.
Accurately Counting Singular Values of Bidiagonal Matrices and Eigenvalues of Skew-Symmetric Tridiagonal Matrices
Authors: K. V. Fernando
Venue: SIAM Journal on Matrix Analysis and Applications (1999)

We have developed algorithms to count singular values of a real bidiagonal matrix which are greater than a specified value. This requires the transformation of the singular value problem to an equivalent symmetric eigenvalue problem. The counting of singular values is paramount in the design of bisection- and multisection-type algorithms for computing singular values on serial and parallel machines.The algorithms are based on the eigenvalues of BBt, BtB, and the 2n x 2n zero--diagonal tridiagonal matrix which is permutationally equivalent to the Jordan--Wielandt form [{\scriptsize ${0 \atop B^t}{B \atop 0}$}], where B is an n x n bidiagonal matrix. The two product matrices, which do not have to be formed explicitly, lead to the progressive and stationary qd algorithms of Rutishauser. The algorithm based on the zero--diagonal matrix, which we have named the Golub--Kahan form, may be considered as a combination of both the progressive and stationary qd algorithms.We study important properties such as the backward error analysis, the monotonicity of the inertia count and the scaling of data which guarantee the accuracy and integrity of these algorithms. For high relative accuracy of tiny singular values, the algorithm based on the Golub--Kahan form is the best choice. However, if such accuracy is not required or requested, the differential progressive and differential stationary qd algorithms with certain modifications are adequate and more efficient.We also show how to transform the real skew-symmetric tridiagonal eigenvalue problem to a real bidiagonal singular value problem. Thus, the eigenvalues of a skew-symmetric matrix can be readily counted using algorithms developed here for bidiagonal matrices.
Error Estimates for a Combined Finite Volume--Finite Element Method for Nonlinear Convection--Diffusion Problems
Authors: Miloslav Feistauer, Jirí Felcman, Mária Lukácová-Medvidová, Gerald Warnecke
Venue: SIAM Journal on Numerical Analysis (1999)

The subject of this paper is the analysis of error estimates of the combined finite volume--finite element (FV--FE) method for the numerical solution of a scalar nonlinear conservation law equation with a diffusion term. Nonlinear convective terms are approximated with the aid of a monotone finite volume scheme considered over the finite volume mesh dual to a triangular grid, whereas the diffusion term is discretized by piecewise linear conforming triangular finite elements. Under the assumption that the exact solution possesses some regularity properties and the triangulations are of a weakly acute type, with the aid of the discrete maximum principle and a priori estimates, error estimates of the method are proved.
Interactive packages for learning image compression algorithms
Authors: Sami Khuri, Hsiu-Chin Hsu
Venue: ACM SIGCSE Bulletin (2000)

This paper introduces three interactive packages for learning image compression algorithms. The first two packages, RLE and Quadtree, animate bitmap image compression algorithms, and the third package, JPEG, is a tutorial about the Joint Photographic Expert Group (JPEG) standard. The goal in designing and developing the packages was to provide instructors with tutorial and demonstration tools for teaching various interesting algorithms to students in CS1/CS2, Data Structures and Algorithms, Data Compression and Image Processing courses. The packages visualize image compression algorithms by displaying their different states of execution, using different colors to highlight the important areas, and providing textual explanations to help users understand the visualization. All three packages are interactive, platform-independent, and easy to use.
Dynamic instrumentation of threaded applications
Authors: Zhichen Xu, Barton P. Miller, Oscar Naim
Venue: ACM SIGPLAN Notices (1999)

The use of threads is becoming commonplace in both sequential and parallel programs. This paper describes our design and initial experience with non-trace based performance instrumentation techniques for threaded programs. Our goal is to provide detailed performance data while maintaining control of instrumentation costs. We have extended Paradyn's dynamic instrumentation (which can instrument programs without recompiling or relinking) to handle threaded programs.Controlling instrumentation costs means efficient instrumentation code and avoiding locks in the instrumentation. Our design is based on low contention data structures. To associate performance data with individual threads, we have all threads share the same instrumentation code and assign each thread with its own private copy of performance counters or timers. The asynchrony in a threaded program poses a major challenge to dynamic instrumentation. To implement time-based metrics on a per-thread basis, we need to instrument thread context switches, which can cause instrumentation code to interleave. Interleaved instrumentation can not only corrupt performance data, but can also cause a scenario we call self-deadlock where an instrumentation code deadlocks a thread. We introduce thread-conscious locks to avoid self-deadlock, and per-thread virtual CPU timers to reduce the chance of interleaved instrumentation accessing the same performance counter or timer, and to reduce the number of expensive timer calls at thread context switches.Our initial implementation is on SPARC Solaris 2.5 and 2.6 including multiprocessor Sun UltraSPARC Enterprise machines. We tested our tool on large multithreaded applications, including the Java Virtual Machine (JVM). We show how our new techniques helped us to speed up a Java graphics native method by 42% and consequently increase by 24% the amount of work that can be done in unit time in a game applet.
Software testing and analysis of object-oriented software
Authors: Jeff Offutt
Venue: ACM SIGSOFT Software Engineering Notes (2000)

Our work has studied new language mechanisms for accessing message invocations in message passing based concurrent programming languages. Invocation handling mechanisms in many concurrent languages have significant limitations that make it difficult or costly to solve common programming situations encountered in program visualization, debugging, and scheduling scenarios. We have defined and implemented new such mechanisms within the SR concurrent language and have gained some experience with them.This work has led us to want a cleaner, higher-level way of defining mechanisms for message invocation. We are, therefore, now taking an object-oriented approach. As a step toward that goal, we are currently applying our ideas to Java.Below, we briefly summarize these two areas.
Analysis and application of adaptive sampling
Authors: James F. Lynch
Venue: Proceedings of the nineteenth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems (2000)

An estimation algorithm for a query is a probabilistic algorithm that computes an approximation for the size (number of tuples) of the query. The main question that is studied is which classes of logically definable queries have fast estimation algorithms. Evidence from descriptive complexity theory is provided that indicates not all such queries have fast estimation algorithms. However, it is shown that on classes of structures of bounded degree, all first-order queries have fast estimation algorithms.These estimation algorithms use a form of statistical sampling known as adaptive sampling. Several versions of adaptive sampling have been developed by other researchers. The original version has been surpassed in some ways by a newer version and a more specialized Monte-Carlo algorithm. An analysis of the average run time of the original version is given, and the different algorithms are compared. The analysis is used to compute what appears to be the best known upper bound on the efficiency of the original algorithm. Also, contrary to what seems to be a commonly held opinion, the two methods of adaptive sampling are incomparable. Which method is superior depends on the query being estimated and the criteria that are being applied. Lastly, adaptive sampling can be more efficient than the Monte-Carlo algorithm if knowledge about the maximum values of the data being sampled is available.
Experiences with parallel job scheduling on a transputer system
Authors: Yuet-Ning Chan, Sivarama P. Dandamudi, Shikharesh Majumdar
Venue: ACM SIGMETRICS Performance Evaluation Review (1999)

Both time and space sharing strategies have been proposed for job scheduling in multiprogrammed parallel systems. This paper summarizes the major observations gained from an experimental investigation of these two partition sharing strategies on a Transputer system. A number of factors such as the applications and their software architectures in the multiprogramming mix, the partition sharing strategy, and the partition size are varied and the resulting insights into system performance and scheduling are presented. Space sharing is observed to produce a superior performance in comparison to time sharing for a number of multiprogrammed workloads. Time sharing showed a better performance for workloads with high variability in process execution times, and with high rates of interprocess communication. The relationships between system performance and a number of workload and system characteristics are presented.
Fibre channel for mass storage
Authors: Ralph H. Thornburgh
Venue:  (1999)

With Fibre Channel, you can suddenly scale your storage systems from gigabytes to terabytes, and improve performance at the same time -- all without disrupting systems, networks, or applications. Fibre Channel for Mass Storage walks you step-by-step through the basics of Fibre Channel technology, and demonstrates how to deploy Hewlett Packard's advanced Fibre Channel products to address your most critical enterprise storage challenges. Coverage includes: Why Fibre Channel has become the enterprise storage technology of choice Fibre Channel's architecture and six functional levels Fibre Channel Arbitrated Loop (FC-AL) -- an exceptionally effective storage system topology Peripheral devices, logical units, and volume set addressing Essential addressing techniques for integrating Fibre Channel with HP-UXFibre Channel for Mass Storage introduces Hewlett-Packard's state-of-the-art Fibre Channel product family, beginning with Tachyon(r), the industry's first Fibre Channel controller fully integrated on a single chip. Learn about Hewlett-Packard's Fibre Channel adapters for K-Class, T-Class, D-Class, and V-Class Enterprise Servers and parallel clusters; hubs, disk arrays, SCSI multiplexers, and more. Finally, preview the future of Fibre Channel: faster fiber rates, hunt groups, multicast groups, classes of service, and beyond.Whether you're implementing Fibre Channel, planning for it, or simply need to understand it, Fibre Channel for Mass Storage has all the answers you're looking for.
A Lower Bound for Integer Multiplication with Read-Once Branching Programs
Authors: Stephen Ponzio
Venue: SIAM Journal on Computing (1999)

We prove that read-once branching programs computing integer multiplication require size $2^{\Omega(\sqrt{n})}$. This is the first nontrivial lower bound for multiplication on branching programs that are not oblivious. By the appropriate problem reductions, we obtain the same lower bound for other arithmetic functions.
Knowledge-based metadata extraction from PostScript files
Authors: Giovanni Giuffrida, Eddie C. Shek, Jihoon Yang
Venue: Proceedings of the fifth ACM conference on Digital libraries (2000)

The automatic document metadata extraction process is animportant task in a world where thousands of documents are just one``click'' away. Thus, powerful indices are necessary to support effective retrieval. The upcoming XML standard represents an important step in this direction as itssemistructuredrepresentation conveys document metadata together with the text of the document. For example, retrieval of scientific papers by authors or affiliations would be a straightforward tasks if papers were stored in XML.Unfortunately, today, the largest majority of documents on the web are available in forms that do not carryadditional semantics. Converting existing documents to a semistructured representation is time consuming and no automatic process can be easily applied. In this paper we discuss a system, based on a novel spatial/visualknowledge principle, for extracting metadata from scientific papers storedas PostScript files. Our system embeds the general knowledge about the graphical layout of a scientific paper to guide the metadata extraction process. Our system can effectively assist the automatic index creation for digital libraries.
Layers of Silence, Arenas of Voice: The Ecology ofVisible and Invisible Work
Authors: Susan Leigh Star, Anselm Strauss
Venue: Computer Supported Cooperative Work (1999)

No work is inherently either visible or invisible. We always &rsquo;&rsquo;see&lsquo;&lsquo; work through a selection of indicators: straining muscles, finished artifacts, a changed state of affairs. The indicators change with context, and that context becomes a negotiation about the relationship between visible and invisible work. With shifts in industrial practice these negotiations require longer chains of inference and representation, and may become solely abstract.This article provides a framework for analyzing invisible work in CSCW systems. We sample across a variety of kinds of work to enrich the understanding of how invisibility and visibility operate. Processes examined include creating a &rsquo;&rsquo;non-person&lsquo;&lsquo; in domestic work; disembedding background work; and going backstage. Understanding these processes may inform the design of CSCW systems and the development of related social theory.
A connectionless approach to integrated network management
Authors: Jairo A. Gutiérrez
Venue: International Journal of Network Management (1998)

As computer networks become more complex and more heterogeneous &lpar;often involving systems from multiple vendors&rpar;, the importance of integrated network management increases. This paper proposes a model to represent an integrated network management environment &lpar;INME&rpar; combining the emerging Web&hyphen;based management standards with the proven&hyphen;and&hyphen;tried network management solutions promoted by the Internet Activities Board, and centred around the Simple Network Management Protocol. &copy; 1998 by John Wiley & Sons, Ltd.
Java and XML
Authors: Brett McLaughlin
Venue:  (2000)

Java revolutionized the programming world by providing a platform-independent programming language. XML takes the revolution a step further with a platform-independent language for interchanging data. Java and XML shows how to put the two together, building real-world applications in which both the code and the data are truly portable.
A Geometric Approach to Betweenness
Authors: Benny Chor, Madhu Sudan
Venue: SIAM Journal on Discrete Mathematics (1998)

An input to the betweenness problem contains m constraints over n real variables (points). Each constraint consists of three points, where one of the points is specified to lie inside the interval defined by the other two. The order of the other two points (i.e., which one is the largest and which one is the smallest) is not specified. This problem comes up in questions related to physical mapping in molecular biology. In 1979, Opatrny showed that the problem of deciding whether the n points can be totally ordered while satisfying the m betweenness constraints is NP-complete [SIAM J. Comput., 8 (1979), pp. 111--114]. Furthermore, the problem is MAX SNP complete, and for every $\alpha> 47/48$ finding a total order that satisfies at least $\alpha$ of the m constraints is NP-hard (even if all the constraints are satisfiable). It is easy to find an ordering of the points that satisfies 1/3 of the m constraints (e.g., by choosing the ordering at random).This paper presents a polynomial time algorithm that either determines that there is no feasible solution or finds a total order that satisfies at least 1/2 of the m constraints. The algorithm translates the problem into a set of quadratic inequalities and solves a semidefinite relaxation of them in ${\cal R}^n. The n solution points are then projected on a random line through the origin. The claimed performance guarantee is shown using simple geometric properties of the semidefinite programming (SDP) solution.