ppxscal/embedding_network huggingface dataset:
Contention in shared memory algorithms
Authors: Cynthia Dwork, Maurice Herlihy, Orli Waarts
Venue: Journal of the ACM (JACM) (1997)

Most complexity measures for concurrent algorithms for asynchronous shared-memory architectures focus on process steps and memory consumption. In practice, however, performance of multiprocessor algorithms is heavily influenced by contention, the extent to which processess access the same location at the same time. Nevertheless, even though contention is one of the principal considerations affecting the performance of real algorithms on real multiprocessors, there are no formal tools for analyzing the contention of asynchronous shared-memory algorithms.This paper introduces the first formal complexity model for contention in shared-memory multiprocessors. We focus on the standard multiprocessor architecture in which n asynchronous processes communicate by applying read, write, and read-modify-write operations to a shared memory. To illustrate the utility of our model, we use it to derive two kinds of results: (1) lower bounds on contention for well-known basic problems such as agreement and mutual exclusion, and (2) trade-offs between the length of the critical path (maximal number of accesses to shared variables performed by a single process in executing the algorithm) and contention for these algorithms. Furthermore, we give the first formal contention analysis of a variety of counting networks, a class of concurrent data structures inplementing shared counters. Experiments indicate that certain counting networks outperform conventional single-variable counters at high levels of contention. Our analysis provides the first formal model explaining this phenomenon.
Promoting Software Reuse Using Self Organizing Maps
Authors: Sushil Acharya, R. Sadananda
Venue: Neural Processing Letters (1997)

Reusability of software, regardless of its utilizing technique, is widely believed to be a promising means for improving software productivity and reliability. However it is not practiced adequately due to the lack of techniques that facilitate the locating of reusable components that are functionally close. In this paper we apply Kohonen&lsquo;s Self-Organizing Maps to develop an approach for promoting Software Reuse. We look at the details of how Self-Organization can arrange and regularize data from the original pattern space into a topology preserving map. We describe a practical implementation of the SOM methodology for Software Reuse using a database of UNIX commands. And finally we briefly present our proposed Software Reuse Methodology.
Five-stage procedure for the evaluation of simulation models through statistical techniques
Authors: Jack P. C. Kleijnen
Venue: Proceedings of the 28th conference on Winter simulation (1996)

This paper recommends the following sequence for the evaluation of simulation models. 1) Validation: the availability of data on the real system determines the proper type of statistical technique. 2) Screening: in the simulation's pilot phase the important inputs are identified through a novel technique, namely sequential bifurcation, which uses aggregation and sequential experimentation. 3) Sensitivity or what-if analysis: the important inputs are analyzed in more detail, including interactions between inputs; relevant techniques are design of experiments (DOE) and regression analysis. 4) Uncertainty or risk analysis: important environmental inputs may have values not precisely known, so the resulting uncertainties in the model outputs are quantified; techniques are Monte Carlo and Latin hypercube sampling. 5) Optimization: policy variables may be controlled, applying Response Surface Methodology (RSM), which combines DOE, regression analysis, and steepest-ascent hill-climbing. This paper summarizes case studies for each stage.
On the Existence and Convergence of the Central Path for Convex Programming and Some Duality Results
Authors: Renato D. C. Monteiro, Fangjun Zou
Venue: Computational Optimization and Applications (1998)

This paper gives several equivalent conditions which guarantee the existence of the weighted central paths for a given convex programming problem satisfying some mild conditions. When the objective and constraint functions of the problem are analytic, we also characterize the limiting behavior of these paths as they approach the set of optimal solutions. A duality relationship between a certain pair of logarithmic barrier problems is also discussed.
COOP'98: improving the design of cooperative systems
Authors: Alain Giboin
Venue: ACM SIGGROUP Bulletin (1998)

COOP'98, the Third International Conference on the Design of Cooperative Systems, was held in Cannes, France, from May 26-29, 1998. It was attended by about 100 people.
Splittings, Robustness, and Structure of Complete Sets
Authors: Harry Buhrman, Albrecht Hoene, Leen Torenvliet
Venue: SIAM Journal on Computing (1998)

We investigate the structure of EXP-complete and hard sets under various kinds of reductions. In particular, we are interested in the way in which information that makes the set complete is stored in the set. We study for various types of reductions the question of whether the set difference A-S for a hard set A and a sparse set S is still hard. We also address the question of which complete sets A can be split into sets A1 and A2 such that $A\equiv^P_r A_1\equiv^P_r A_2$ for reduction type r, i.e., which complete sets are mitotic. We obtain both positive and negative answers to these questions depending on the reduction type and the structure of the sparse set.
A position paper on compile-time program analysis
Authors: Barbara G. Ryder
Venue: ACM SIGPLAN Notices (1997)

Current challenges to the compile-time analysis research community include unifying the nomenclature in program analysis, embedding analyses in practical software tools, influencing programming language design to allow analysis, and adapting analyses to the blend of architectures, languages and operating systems common in modern software. These challenges must be met to ensure that compile-time analyses will continue to be of practical benefit.
A relational interface for heterogeneous information sources
Authors: Ee-Peng Lim, Wee Keong Ng
Venue: Proceedings of the IEEE international forum on Research and technology advances in digital libraries (1997)

The World Wide Web today consists of a vast repository of diverse information distributed geographically across different locations. In the near future, this wealth of information will constitute the major bulk of information resources for digital library systems. To provide integrated access to web and other kinds of information sources, we believe that it is useful to first classify the space of digital library resources into "collection" and "reference spaces". Searching can be done by first querying the indices or metadata in the reference space, followed by retrieving the documents or data from the collection space. In this paper, we present an integrated SQL query interface for web search engines, bibliographic and relational databases. Bibliographic databases, web search engines and certain structured databases are important sources of information within the reference space. By extending the relational data model and the SQL language with new predicates, our integrated approach permits a user to specify complex queries to any or all of the three types of information sources simultaneously. This complex query service in turn improves the effectiveness of searching within the reference space.
Automated Query Formulation Using an Entity&ndash;Relationship Conceptual Schema
Authors: Ralph D. Semmel, James Mayfield
Venue: Journal of Intelligent Information Systems (1997)

Significant effort is expended in developing a high&ndash;level conceptual schema for a relational database. However, critical knowledge is often discarded when the conceptual schema is mapped to a set of relation schemas. As a result, designers and users must employ sparser logical&ndash;level knowledge to access data. Unfortunately, naive users do not possess the detailed logical&ndash;level knowledge required to formulate queries corresponding to ad hoc requests. A universal relation interface can shield users from underlying design details. However, most universal relation systems have been based on abstractions not typically used by database designers. Consequently, the usefulness of these interfaces has been limited. This article demonstrates how an Entity&ndash;Relationship (ER) conceptual schema can be used by a high&ndash;level interface to formulate queries automatically. The notion of contexts is introduced to describe the segmentation of an ER conceptual schema into overlapping subgraphs that correspond to sets of relations that can be joined in a lossless manner. Given a set of contexts, natural join query formulation is straightforward. As demonstrated with a case study using the prototype QUICK system, the techniques presented facilitate the construction of high&ndash;level, intelligent interfaces.
Performing Work Efficiently in the Presence of Faults
Authors: Cynthia Dwork, Joseph Y. Halpern, Orli Waarts
Venue: SIAM Journal on Computing (1998)

We consider a system of t synchronous processes that communicate only by sending messages to one another, and together the processes must perform n independent units of work. Processes may fail by crashing; we want to guarantee that in every execution of the protocol in which at least one process survives, all n units of work will be performed. We consider three parameters: the number of messages sent, the total number of units of work performed (including multiplicities), and time. We present three protocols for solving the problem. All three are work optimal, doing O(n+t) work. The first has moderate costs in the remaining two parameters, sends $O(t\sqrt{t})$ messages, and takes O(n+t) time. This protocol can be easily modified to run in any completely asynchronous system equipped with a failure detection mechanism. The second sends only O(t log t) messages, but its running time is large (O(t2(n+t) 2n+t)). The third is essentially time optimal in the (usual) case in which there are no failures, and its time complexity degrades gracefully as the number of failures increases.
Per Brinch Hansen's concerns about high performance Fortran
Authors: Carl D. Offner
Venue: ACM SIGPLAN Notices (1998)

Per Brinch Hansen's criticisms of High Performance Fortran in the March issue of this journal are examined and shown to be without foundation.
Eye Tracking in Image Sequences by Competitive Neural Networks
Authors: Giuseppe Marcone, Giuseppe Martinelli, Lamberto Lancetti
Venue: Neural Processing Letters (1998)

An automatic algorithm is presented for the eye tracking within face image sequences. It is based on the property of local Gabor filters to efficiently determine the location of eyes in face images. The proposed algorithm is implemented by a competitive neural network, that locates and tracks the eyes in a reliable manner as shown by experimental results.
Quasideterminant Characterization of MDS Group Codes overAbelian Groups
Authors: A. A. Zain, B. Sundar Rajan
Venue: Designs, Codes and Cryptography (1998)

A group code defined over a group G is a subset of G^n which forms a group under componentwise group operation. The well known matrix characterization of MDS (Maximum Distance Separable) linear codes over finite fields is generalized to MDS group codes over abelian groups, using the notion of quasideterminants defined for matrices over non-commutative rings.
Optimal wire-sizing function with fringing capacitance consideration
Authors: Chung-Ping Chen, D. F. Wong
Venue: Proceedings of the 34th annual Design Automation Conference (1997)

In this paper, we consider non-uniform wire-sizing under theElmore delay model.Given a wire segment of length L, letf(x) be the width of the wire at position x, 0 ¿ x ¿ L.It was shown in [Optimal Wire-sizing formula under the Elmore delay model, Shaping a distributed-RC line to minimize Elmore delay] that the optimal wire-sizing functionwhich minimizes delay is an exponential tapering functionf(x) = ae{-bx}, where a > 0 and b > 0 are constants.Unfortunately, [Optimal Wire-sizing formula under the Elmore delay model, Shaping a distributed-RC line to minimize Elmore delay] did not consider fringing capacitancewhich is at least comparable in size to area capacitance indeep submicron designs.As a result, exponential taperingis no longer the optimal strategy.In this paper, we showthat the optimal wire-sizing function, taking fringing capacitanceinto consideration, is f(x) = \frac{{ - c_f }}{{2c_0 }}(\frac{1}{{W(\frac{{ - c_f }}{{ae^{ - bx} }})}} + 1) whereW(x) = \sum\nolimits_{n = 1}^\infty{\frac{{( - n)^{n - 1} }}{{n!}}} x^n is the Lambert's W function, c{f}and c{0} are the respective fringing capacitance and area capacitanceof wire per unit square, a > 0 and b> 0 are constants.The optimal wire-sizing function degenerates into an exponentialtapering function as c}{f} = 0, and degenerates into asquare-root tapering function (f(x)=\sqrt {b - ax}, where a > 0and b > 0) as c{f} ¿ ¿.Our experimental results show thatthe optimal wire-sizing function can significantly reduce theinterconnection delay of exponentially tapered wires.In thecase where lower and upper bounds on the wire widths aregiven, the optimal wire-sizing function is a truncated versionof the above function.Finally, our optimal wire-sizing functioncan be iteratively applied to optimally size all the wiresegments in a routing tree for objectives such as minimizingweighted sink delay, minimizing maximum sink delay, orminimizing area subject to delay bounds at the sinks.
A &ldquo;Fourier Transform&rdquo; for Multiplicative Functionson Non-Crossing Partitions
Authors: Alexandru Nica, Roland Speicher
Venue: Journal of Algebraic Combinatorics: An International Journal (1997)

We describe the structure of the group of normalized multiplicative functions on lattices of non-crossing partitions. As an application, we give a combinatorial proof of a theorem of D. Voiculescu concerning the multiplication of free random variables
Performance debugging shared memory parallel programs using run-time dependence analysis
Authors: Ramakrishnan Rajamony, Alan L. Cox
Venue: Proceedings of the 1997 ACM SIGMETRICS international conference on Measurement and modeling of computer systems (1997)

We describe a new approach to performance debugging that focuses on automatically identifying computation transformations to reduce synchronization and communication. By grouping writes together into equivalence classes, we are able to tractably collect information from long-running programs. Our performance debugger analyzes this information and suggests computation transformations in terms of the source code. We present the transformations suggested by the debugger on a suite of four applications. For Barnes-Hut and Shallow, implementing the debugger suggestions improved the performance by a factor of 1.32 and 34 times respectively on an 8-processor IBM SP2. For Ocean, our debugger identified excess synchronization that did not have a significant impact on performance. ILINK, a genetic linkage analysis program widely used by geneticists, is already well optimized. We use it only to demonstrate the feasibility of our approach to long-running applications.We also give details on how our approach can be implemented. We use novel techniques to convert control dependences to data dependences, and to compute the source operands of stores. We report on the impact of our instrumentation on the same application suite we use for performance debugging. The instrumentation slows down the execution by a factor of between 4 and 169 times. The log files produced during execution were all less than 2.5 Mbytes in size.
Assessing process-centered software engineering environments
Authors: Vincenzo Ambriola, Reidar Conradi, Alfonso Fuggetta
Venue: ACM Transactions on Software Engineering and Methodology (TOSEM) (1997)

Process-centered software engineering environments (PSEEs) are the most recent generation of environments supporting software development activities. They exploit an representation of the process (called the process model that specifies how to carry out software development activities, the roles and tasks of software developers, and how to use and control software development tools. A process model is therefore a vehicle to better understand and communicate the process. If it is expressed in a formal notation, it can be used to support a variety of activities such as process analysis, process simulation, and process enactment. PSEEs provide automatic support for these activities. They exploit languages based on different paradigms, such as Petri nets and rule-based systems. They include facilities to edit and analyze process models. By enacting the process model, a PSEE provides a variety of services, such as assistance for software developers, automation of routine tasks, invocation and control of software development tools, and enforcement of mandatory rules and practices. Several PSEEs have been developed, both as research projects and as commercial products. The initial deployment and exploitation of this technology have made it possible to produce a significant amount of experiences, comments, evaluations, and feedback. We still lack, however, consistent and comprehensive assessment methods that can be used to collect and organize this information. This article aims at contributing to the definition of such methods, by providing a systematic comparison grid and by accomplishing an initial evaluation of the state of the art in the field. This evaluation takes into account the systems that have been developed by the authors in the past five years, as well as the main characteristics of other well-known environments
Improved Randomized On-Line Algorithms for the List Update Problem
Authors: Susanne Albers
Venue: SIAM Journal on Computing (1998)

The best randomized on-line algorithms known so far for the list update problem achieve a competitiveness of $\sqrt{3} \approx 1.73$. In this paper we present a new family of randomized on-line algorithms that beat this competitive ratio. Our improved algorithms are called TIMESTAMP algorithms and achieve a competitiveness of $\max\{2-p, 1+p(2-p)\}$, for any real number $p\in[0,1]$. Setting $p = (3-\sqrt{5})/2$, we obtain a $\phi$-competitive algorithm, where $\phi = (1+\sqrt{5})/2\approx 1.62$ is the golden ratio. TIMESTAMP algorithms coordinate the movements of items using some information on past requests. We can reduce the required information at the expense of increasing the competitive ratio. We present a very simple version of the TIMESTAMP algorithms that is \mbox{$1.68$-competitive}. The family of TIME\-STAMP algorithms also includes a new deterministic 2-competitive on-line algorithm that is different from the MOVE-TO-FRONT rule.
Beyond market baskets: generalizing association rules to correlations
Authors: Sergey Brin, Rajeev Motwani, Craig Silverstein
Venue: Proceedings of the 1997 ACM SIGMOD international conference on Management of data (1997)

One of the most well-studied problems in data mining is mining for association rules in market basket data. Association rules, whose significance is measured via support and confidence, are intended to identify rules of the type, &ldquo;A customer purchasing item A often also purchases item B.&rdquo; Motivated by the goal of generalizing beyond market baskets and the association rules used with them, we develop the notion of mining rules that identify correlations (generalizing associations), and we consider both the absence and presence of items as a basis for generating rules. We propose measuring significance of associations via the chi-squared test for correlation from classical statistics. This leads to a measure that is upward closed in the itemset lattice, enabling us to reduce the mining problem to the search for a border between correlated and uncorrelated itemsets in the lattice. We develop pruning strategies and devise an efficient algorithm for the resulting problem. We demonstrate its effectiveness by testing it on census data and finding term dependence in a corpus of text documents, as well as on synthetic data.
Classes of Graphs that Are Not Vertex Ramsey
Authors: H. A. Kierstead
Venue: SIAM Journal on Discrete Mathematics (1997)

Sauer [Combinatorics, 1 (1993), pp. 361--377] has conjectured that for any tree T and any clique K, the class Forb(T, K) of graphs that induces neither T nor K is not vertex Ramsey. This conjecture is implied by an even stronger conjecture of Gyárfás and independently by Sumner, that Forb(T, K) is $\chi$-bounded. Until now, for all trees T, if Forb(T, K) was known to not be vertex Ramsey, then Forb(T, K) was also known to be $\chi$-bounded. In this paper we introduce a new class of trees, spiders with toes, which includes all trees T such that Forb(T) is known to be $\chi$-bounded as well as other trees for which it is not known to be $\chi$-bounded. We show that for every spider with toes T, Forb(T, K) is not vertex Ramsey.
Intelligent control in space exploration: interval computations are needed
Authors: Hung T. Nguyen, Vladik Kreinovich
Venue: ACM SIGNUM Newsletter (1997)

This paper is a short overview of our NASA-supported research into the necessity of using interval-based intelligent control techniques for space exploration. This is a reasonably new application area for interval computations, and we hope that the overviewed results and problems will be of some interest to the numerical computations community.This paper is a short version of our detailed report presented to NASA.
Integrating professionalism into undergraduate degree courses in computing (panel)
Authors: L. R. Neal, A. D. Irons
Venue: Proceedings of the 6th annual conference on the teaching of computing and the 3rd annual conference on Integrating technology into computer science education: Changing the delivery of computer science education (1998)

Graduates of degree programmes in computing are generally assumed to be seeking careers as professionals in information systems. Consequently, in the UK, nearly all courses seek accreditation through the professional institute for information systems engineering, the British Computer Society. Such accreditation signifies that graduates have satisfied the educational requirements for the recognised professional engineering status of Chartered Engineer. One requirement for such accreditation is that a range of professional issues are covered in the degree programme that are relevant to the branch of engineering addressed. This paper discusses the need for professionalism to be an integral part of any computing degree, with examples of implementation within the Department of Information Systems at Brunel University and at the University of Northumbria at Newcastle.
Revised Definition of Optical Flow: Integration of Radiometric and Geometric Cues for Dynamic Scene Analysis
Authors: Shahriar Negahdaripour
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1998)

Optical flow has been commonly defined as the apparent motion of image brightness patterns in an image sequence. In this paper, we propose a revised definition to overcome shortcomings in interpreting optical flow merely as a geometric transformation field. The new definition is a complete representation of geometric and radiometric variations in dynamic imagery. We argue that this is more consistent with the common interpretation of optical flow induced by various scene events. This leads to a general framework for the investigation of problems in dynamic scene analysis, based on the integration and unified treatment of both geometric and radiometric cues in time-varying imagery. We discuss selected models, including the generalized dynamic image model in [21], for the estimation of optical flow. We show how various 3D scene information are encoded in, and thus may be extracted from, the geometric and radiometric components of optical flow. We provide selected examples based on experiments with real images.