ppxscal/embedding_network huggingface dataset:
Efficient and portable parallel algorithms for cholesky decomposition
Authors: Eunice Santos
Venue:  (2003)

In this dissertation we consider design issues such as data, layout, data, dependency, communication scheduling, and parallel models in order to develop parallel algorithms for Cholesky decomposition. Our intention is to design efficient and portable parallel algorithms for large scale dense linear systems to be run in the distributed memory environment. To consider the issue of portability, we utilize the well known LogP model for designing parallel algorithms and for performing theoretical run time analysis. We developed a contention free communication scheduling for the parallel algorithms in order to reduce the communication cost. To study the impact of data layout on performance, we designed the parallel algorithms based on column, row and block data distribution utilizing the fan-in and fan-out methods. Specifically we introduced panel size for 1D layouts and granularity size for 2D layouts for the task partitioning. To determine the efficiency of the parallel algorithms, we derived lower bound results and theoretical run time performance. The analysis on the parallel algorithms shows that parallel algorithms for 1D data layouts are optimal. However for 2D data layouts, the parallel algorithms are efficient, if not necessarily asymptotically optimal. We then implemented the parallel algorithms using MPI. The experimental results show that fan-in outperforms fan-out for 2D layouts, especially for larger processor size. The performance for the 1D fan-out row-based parallel algorithm was no worse than that of the column-based parallel algorithms. This seems to refute the common notion that row-based parallel algorithms are not, as efficient as column-based parallel algorithms. The experimental results indicated that performance was impacted as panel size and/or granularity size varied. This provides insights that the constant factors for lower bound and run time performance call not be ignored.
Virtual Communities for Software Maintenance
Authors: Helena Holmström
Venue: Proceedings of the Proceedings of the 37th Annual Hawaii International Conference on System Sciences (HICSS'04) - Track 7 - Volume 7 (2004)

This paper recognizes the use of virtual communities for software maintenance. On the basis of an empirical study of a game community it is suggested that virtual communities can be deployed for the different types of software maintenance -- software fault repair, software adaptation and software functionality addition or modification. On a general level, the study suggests that virtual communities are beneficial for the elicitation of changing user needs and requirements and for user-user interaction. More specifically, the study suggests that there are specific benefits of virtual communities in relation to each phase in the maintenance process. Finally, characteristics in terms of self-supporting' and self-generating'are identified as community-specific characteristics that are beneficial to the software maintenance process.
Kirkman triple systems and their generalizations: a survey
Authors: Rolf S. Rees, W. D. Wallis
Venue: DESIGNS 2002: Further computational and constructive design theory (2003)

Over 150 years ago, the Reverend T.P. Kirkman posed the following problem as Query 6 in the Lady's and Gentlemen's Diary [26].Fifteen young ladies in a school walk out three abreast for seven days in succession: it is required to arrange them daily, so that no two will walk twice abreast.Both Kirkman [27] and Cayley [13] published solutions to this problem in that same year. The search for a solution to the general problem of arranging v ≡ 3(mod 6) ladies into groups of three over a series of (v - 1)/2 days became known as the Kirkman Schoolgirl Problem, one of the most famous problems in combinatorial design theory. It took well over a century before the first published proof of the existence of these designs for all v ≡ 3(mod 6) was given by D.K. Ray-Chaudhuri and R.M. Wilson [38].In this paper we update and expand upon the survey on Kirkman Triple Systems and related designs published by D.R. Stinson a decade ago [51]. The study of various generalizations of the Kirkman Schoolgirl Problem remains a very active area of research, and much work has been done in the past ten years. This paper does not cover all of the topics discussed in Stinson's survey; on the other hand we discuss several topics not covered by that survey. Thus our paper is not meant so much to replace Stinson's survey as it is to complement it.
TVD-interpolating matrix method prediction of flow with heat transfer
Authors: L. Hanich, M. Louaked
Venue: Journal of Computational Physics (2004)

The use of the Interpolating Matrix Method to investigate the dynamical behaviour of natural convection flow will form the main focus of the work. We design an original and efficient numerical algorithm that mimic TVD constraints to rule out spurious overshoots and oscillations that appear near steep gradients, to solve fluid flow and heat transfer equations, and compare the results to some Benchmark numerical solutions.
User and social interfaces by observing human faces for intelligent wheelchairs
Authors: Yoshinori Kuno, Yoshifumi Murakami, Nobutaka Shimada
Venue: Proceedings of the 2001 workshop on Perceptive user interfaces (2001)

With the increase in the number of senior citizens, there is a growing demand for human-friendly wheelchairs as mobility aids. Thus several intelligent wheelchairs have been proposed recently. However, they consider friendliness only to their users. Since wheelchairs move among people, they should also be friendly to people around them. In other words, they should have a social-friendly interface as well as a user-friendly interface. We propose an intelligent wheelchair that is friendly to both user and people around it by observing the faces of both user and others. The user can control it by turning his/her face in the direction where he/she would like to turn. It observes pedestrian's face and changes its collision avoidance method depending on whether or not he/she notices it. Here we assume that the pedestrian notices the wheelchair if his/her face often faces toward the wheelchair.
Access Cost Estimation for Unified Grid Storage Systems
Authors: Kurt Stockinger, Heinz Stockinger, Lukasz Dutka, Renata Slota, Darin Nikolow, Jacek Kitowski
Venue: Proceedings of the 4th International Workshop on Grid Computing (2003)

In typical Data Grids large amounts of replicated dataare stored all over the globe in different storage systemswith access latencies ranging from seconds to hours. Thetask of a replica management system is not only to keeptrack of the replicas but also to select those replicas thatcan be accessed by an application program with a minimalresponse or transfer time. Most wide-area replicationresearch focuses on network-based replica selection. However,our past experience with Data Grids has shown thatoften hierarchical storage systems are the main bottleneckrather than network links. This is due to the fact that accesslatencies of hierarchical storage systems can be of theorder of seconds up to hours in case the data resides on atape that is not mounted yet.In this paper we give an overview of our replica managementframework called Reptor and a storage system costestimator that is used. Furthermore, we give details on accessestimation of file replicas that reside on hierarchicalstorage systems. The results show that the access estimatesprovide a good basis for a replica management system toperform efficient replica selection.
Transparent optimisation of rewriting combinators
Authors: Richard J. Boulton
Venue: Journal of Functional Programming (1999)

The LCF system was the first mechanical theorem prover to be user-programmable via a metalanguage, ML, from which the functional programming language Standard ML has been developed. Paulson has demonstrated how a modular rewriting engine can be implemented in LCF. This provides both clarity and flexibility. This paper shows that the same modular approach (using higher-order functions) allows transparent optimisation of the rewriting engine; performance can be improved while few, if any, changes are required to code written using these functions. The techniques described have been implemented in the HOL system, a descendant of LCF, and some are now in daily use. Comparative results are given. Some of the techniques described, in particular ones to avoid processing parts of a data structure that do not need to be changed, may be of more general use in functional programming and beyond.
Multi-resolution disambiguation of term occurrences
Authors: Einat Amitay, Rani Nelken, Wayne Niblack, Ron Sivan, Aya Soffer
Venue: Proceedings of the twelfth international conference on Information and knowledge management (2003)

We describe a system for extracting mentions of terms such as company and product names, in a large and noisy corpus of documents, such as the World Wide Web. Since natural language terms are highly ambiguous, a significant challenge in this task is disambiguating which occurrences of each term are truly related to the right meaning, and which are not. We describe our approach for disambiguation, and show that it achieves very high accuracy with only limited training. This serves as a necessary first step for applications that strive to do analytics on term mentions.
Three-dimensional atom probe investigation of Co/Al thin film reaction
Authors: V. Vovk, G. Schmitz, R. Kirchheim
Venue: Microelectronic Engineering (2003)

The reactive interdiffusion of Co/Al bi-layers is investigated by means of atom probe tomography. The samples are prepared by deposition of corresponding materials onto W substrate tips with a radius of curvature of ∼50 nm. Nucleation of Al9Co2 phase particles is detected only after reaching a critical concentration gradient of ∼0.3 nm-1 at the interface. The fast growth of the particles before the formation of a dense layer is explained by atomic transport through the incoherent interphase boundary. After consumption of the remaining pure Al, B2-ordered AlCo is detected as a second product phase.
A genetic algorithm approach to cartographic map generalisation
Authors: Ian D. Wilson, J. Mark Ware, J. Andrew Ware
Venue: Computers in Industry (2003)

Rendering map data at scales smaller than their source can give rise to map displays exhibiting graphic conflict, such that objects are either too small to be seen or too close to each other to be distinguishable. Furthermore, scale reduction will often require important features to be exaggerated in size, sometimes leading to overlapping features. Cartographic map generalisation is the process by which any graphic conflict that arises during scaling is resolved. In this paper, we show how a Genetic Algorithm (GA) approach was used to resolve spatial conflict between objects after scaling, achieving near optimal solutions within practical time constraints.
Analysis of X.500 distributed directory refresh strategies
Authors: David W. Bachmann, Michael A. Bauer, J. Michael Bennett, Guy A. Fasulo, Michael H. Kamlet, Kevin H. Klinge, Sailesh Makkapati, Jacob Slonim, Toby J. Teorey
Venue: Proceedings of the 1991 conference of the Centre for Advanced Studies on Collaborative research (1991)

Refresh strategies for distributed database directories, commonly recommended for the X.500 standard, are defined and analytically modeled for variations on push/pull and total/differential options under ideal asynchronous control conditions. The models are implemented in a HyperCard-based tool called DirMod ("Directory Model"). Experimental test results show an important elapsed time/performance trade-off among the different strategies, and test data contribute to the verification of the models.
Chip Package Co-Design of a Heterogeneously Integrated 2.45GHz CMOS VCO using Embedded Passives in a Silicon Package
Authors: Ghanshyam Nayak, P. R. Mukund
Venue: Proceedings of the 17th International Conference on VLSI Design (2004)

Phase Noise Performance of a Voltage ControlledOscillator that determines spectral purity is dependent onthe Quality Factor (Q) of the tank in LC Oscillators. On-chipinductors that are used to realize the LC tank havecomparatively low quality factors and consumeconsiderable die area. Here a Chip-Package Co-Designfor a 2.45GHz VCO is described using a high Q (~30)inductor embedded in a silicon substrate. Theheterogeneously integrated circuit has a phase noise of -110dBc/Hz at a 100kHz offset with power dissipation of28mW from a 2.5V supply and has a tuning range of 6%.The resulting improvement in inductor coil quality factor,phase noise and area savings compared to a fullyintegrated VCO design is demonstrated.
Order-preserving maps from a poset to a chain, the order polytope, and the Todd class of the associated toric variety
Authors: Hugh Thomas
Venue: European Journal of Combinatorics (2003)

We give a new formula for the number of order-preserving maps from a finite poset Q to a finite chain, which sums a contribution from each face of the order polytope of Q. The formula we derive could also be obtained if we knew that a certain cycle represented the Todd class of the toric variety associated to Q. We conjecture that, for toric varieties arising from posets, this cycle does represent the Todd class; we prove this conjecture in the case where Q is a chain.
Maintaining the own responsibility: selected information systems architecture, selective outsourcing and organizational learning as a base for a sustainable positioned information technology service
Authors: Ruediger Weissbach
Venue: Managing IT in government business & communities (2003)

This chapter introduces an alternative concept against the dominating trend of a complete outsourcing of IT services, especially in small and medium-sized enterprises (SME). It argues that the undiscriminating adoption of this trend tends to reduce IT on a cost factor and neglects the importance of specific IT knowledge for the continuous improvement of business processes. Also, it neglects the importance of a "communication interface" between the IS users on the one hand and the software development and IT production on the other hand.In opposition to leading management trends, this chapter will present an approach that bases on an interval competence centre for IS and that demands a steady communication between the IT staff and the various departments. In this approach, only selected IT services are externalized and the continuing growth of specific IS knowledge is essential.This approach was developed since the end of the 1990s at the building society, with about 100 employees, in which the author is working.
Flexible intrinsic evaluation of hierarchical clustering for TDT
Authors: James Allan, Ao Feng, Alvaro Bolivar
Venue: Proceedings of the twelfth international conference on Information and knowledge management (2003)

The Topic Detection and Tracking (TDT) evaluation program has included a "cluster detection" task since its inception in 1996. Systems were required to process a stream of broadcast news stories and partition them into non-overlapping clusters. A system's effectiveness was measured by comparing the generated clusters to "truth" clusters created by human annotators. Starting in 2003, TDT is moving to a more realistic model that permits overlapping clusters (stories may be on more than one topic) and encourages the creation of a hierarchy to structure the relationships between clusters (topics). We explore a range of possible evaluation models for this modified TDT clustering task to understand the best approach for mapping between the human-generated "truth" clusters and a much richer hierarchical structure. We demonstrate that some obvious evaluation techniques fail for degenerate cases. For a few others we attempt to develop an intuitive sense of what the evaluation numbers mean. We settle on some approaches that incorporate a strong balance between cluster errors (misses and false alarms) and the distance it takes to travel between stories within the hierarchy.
Leaves in Representation Diagrams of Bipartite Distance-Regular Graphs
Authors: Michael S. Lang
Venue: Journal of Algebraic Combinatorics: An International Journal (2003)

Let &Gamma; denote a bipartite distance-regular graph with diameter D &ge; 3 and valency k &ge; 3. Let &theta;0 > &theta;1 &middot;&middot;&middot; > &theta;D denote the eigenvalues of &Gamma; and let qhij (0 &le; h, i, j &le; D) denote the Krein parameters of &Gamma;. Pick an integer h (1 &le; h &le; D &minus; 1). The representation diagram &Delta; &equals; &Delta;h is an undirected graph with vertices 0,1,&hellip;,D. For 0 &le; i, j &le; D, vertices i, j are adjacent in &Delta; whenever i &ne; j and qhij &ne; 0. It turns out that in &Delta;, the vertex 0 is adjacent to h and no other vertices. Similarly, the vertex D is adjacent to D &minus; h and no other vertices. We call 0, D the trivial vertices of &Delta;. Let l denote a vertex of &Delta;. It turns out that l is adjacent to at least one vertex of &Delta;. We say l is a leaf whenever l is adjacent to exactly one vertex of &Delta;. We show &Delta; has a nontrivial leaf if and only if &Delta; is the disjoint union of two paths.
Hicks' trade cycle revisited: cycles and bifurcations
Authors: M. Gallegati, L. Gardini, T. Puu, I. Sushko
Venue: Mathematics and Computers in Simulation (2003)

In the Trade Cycle, Hicks introduced the idea that endogenous fluctuations could be coupled with a growth process via nonlinear processes. To argue for this hypothesis, Hicks used a piecewise-linear model. This paper shows the need for a reinterpretation of Hicks' contribution in the light of a more careful mathematical investigation. In particular, it will be shown that only one bound is needed to have non explosive outcome if the equilibrium point is an unstable focus. It will also be shown that when the fixed point is unstable the attracting set has a particular structure: It is a one-dimensional closed invariant curve, made up of a finite number of linear pieces, on which the dynamics are either periodic or quasi-periodic. The conditions under which the model produces periodic or quasi-periodic trajectories and the related bifurcations as a function of the main economic parameters are determined.
Critical Exponents, Colines, and Projective Geometries
Authors: Joseph P. S. Kung
Venue: Combinatorics, Probability and Computing (2000)

In [9, p. 469], Oxley made the following conjecture, which is a geometric analogue of a conjecture of Lov&aacute;sz (see [1, p. 290]) about complete graphs.Conjecture 1.1. Let G be a rank-n GF(q)-representable simple matroid with critical exponent n &minus; &gamma;. If, for every coline X in G, c(G&#x002F;X; q) = c(G; q) &minus; 2 = n &minus; &gamma; &minus; 2, then G is the projective geometry PG(n &minus; 1, q).We shall call the rank n, the critical &lsquo;co-exponent&rsquo; &gamma;, and the order q of the field the parameters of Oxley's conjecture. We exhibit several counterexamples to this conjecture. These examples show that, for a given prime power q and a given positive integer &gamma;, Oxley's conjecture holds for only finitely many ranks n. We shall assume familiarity with matroid theory and, in particular, the theory of critical problems. See [6] and [9].A subset C of points of PG(n &minus; 1, q) is a (&gamma;, k)-cordon if, for every k-codimensional subspace X in PG(n &minus; 1, q), the intersection C &cap; X contains a &gamma;-dimensional subspace of PG(n &minus; 1, q). In this paper, our primary interest will be in constructing (&gamma;, 2)-cordons. With straightforward modifications, our methods will also yield (&gamma;, k)-cordons.Complements of counterexamples to Oxley's conjecture are (&gamma;, 2)-cordons.
Estimating an Endogenous Growth Model with Public Capital and GovernmentBorrowing: U.S. and Germany 1960&ndash;1995
Authors: Alfred Greiner, Willi Semmler, Gang Gong
Venue: Computational Economics (2004)

The paper presents and estimates an endogenous growth model with public capital and government borrowing. Government behavior (tax rates, spending and borrowing) does not follow optimizing rules but is restricted by two fiscal regimes (rules). In the strict fiscal regime government borrowing is used for public investment only. In the less strict regime it can also be used for public investment and to a certain degree for the debt service. The growth rate differs in our model variants according to which rule is adopted. Moreover, the growth maximizing income tax rate is different from zero. For the two relevant fiscal regimes, which correspond roughly to the cases of the U.S. and Germany, the model is estimated by employing time series data from 1960.4 to 1992.1 and 1966.1 to 1995.1 respectively. The results suggest an explanation for the different time paths of economic variables in the American and German economies in the post-war period.
Nearest-Neighbours for Time Series
Authors: Juan Manuel Gimeno Illa, Javier Béjar Alonso, Miquel Sànchez Marré
Venue: Applied Intelligence (2004)

This paper presents an application of lazy learning algorithms in the domain of industrial processes. These processes are described by a set of variables, each corresponding a time series. Each variable plays a different role in the process and some mutual influences can be discovered.A methodology to study the different variables and their roles in the process are described. This methodology allows the structuration of the study of the time series.The prediction methodology is based on a k-nearest neighbour algorithm. A complete study of the different parameters of this kind of algorithm is done, including data preprocessing, neighbour distance, and weighting strategies. An alternative to Euclidean distance called shape distance is presented, this distance is insensitive to scaling and translation. Alternative weighting strategies based on time series autocorrelation and partial autocorrelation are also presented.Experiments using autorregresive models, simulated data and real data obtained from an industrial process (Waste water treatment plants) are presented to show the feasabilty of our approach.
Sandpile group on the graph Dn of the dihedral group
Authors: Arnaud Dartois, Francesca Fiorenzi, Paolo Francini
Venue: European Journal of Combinatorics (2003)

In this paper we study the structure of the Abelian sandpile group on the Cayley graph Dn of the dihedral group Dn = 〈a, b | an = b2 = (ab)2 = 1〉. We prove that the Smith normal form of the sandpile group is not cyclic as one can generally expect but is always the direct product of two or three cyclic groups. We conclude by considering some particular cases.