ppxscal/embedding_network huggingface dataset:
Notes about the last principal component
Authors: Jean-Daniel Rolle
Venue: Applied Mathematics and Computation (2002)

This article gives results specifically related to the last principal component. This linear combination of variables plays an important role when one tries to fit a hyperplane to a cloud of points. In data analysis, variables are often subject to a linear transformation. The results that we provide here take account of such a transformation. Firstly, we define a 'distance' between a variable and a set U of variables. Among the linear combinations of the variables in U, the last principal component is the most 'distant' from U. Secondly, we clarify the link between the last principal component and (i) linear dependence, (ii) equation of an optimal hyperplane, and (iii) invariance of the optimal hyperplane under linear transformation of the variables. Finally, we show how the decomposition formula of inertia of a hyperplane in principal component analysis and the decomposition formula of the total sum of squares in linear regression both derive from a common principle.
Global solutions to a one-dimensional hyperbolic free boundary problem which arises in peeling phenomena
Authors: Kazuaki Nakane, Tomoko Shinohara
Venue: Journal of Computational and Applied Mathematics (2003)

This problem arises from the physical model "Peel a thin film from a domain". The behavior of the peeling front is governed by a hyperbolic equation. As the first step, the one-dimensional case is treated. The local solutions have been already given. In this note, the global solution is constructed under the assumption the peeling speed is non negative.
The Coevolution of New Organizational Forms
Authors: Arie Y. Lewin, Chris P. Long, Timothy N. Carroll
Venue: Organization Science (1999)

This paper outlines an alternative theory of organization-environment coevolution that generalizes a model of organization adaptation first proposed by March (1991), linking firm-level exploration and exploitation adaptations to changes in the population of organizations. The theory considers organizations, their populations, and their environments as the interdependent outcome of managerial actions, institutional influences, and extra-institutional changes (technological, sociopolitical, and other environmental phenomena). In particular, the theory incorporates potential differences and equifinal outcomes related to country-specific variation. The basic theses of this paper are that firm strategic and organization adaptations coevolve with changes in the environment (competitive dynamics, technological, and institutional) and organization population and forms, and that new organizational forms can mutate and emerge from the existing population of organizations. The theory has guided a multicountry research collaboration on strategic and organization adaptations and the mutation and emergence of new organizational forms from within the existing population of organizations.
Communities of design practice in electronic government
Authors: Richard Halstead-Nussloch, Doris Konneh, Robert Woodruff
Venue: CHI '03 extended abstracts on Human factors in computing systems (2003)

As we move towards more online governmental services-electronic government or e-government-our information technology (IT) and human-computer interaction (HCI) designs must both broaden and deepen. In Georgia, we have fostered communities of design practice (CDPs) that focus on IT and HCI design at the statewide enterprise level through the Georgia Digital Academy (GDA). In this study, we utilized observational methods and a participatory analysis of the CDP formation in the GDA. Our findings and conclusions converge with the growing body of knowledge on HCI communities of practice. We report our results and recommendations on how CDPs might be utilized to build effective e-government.
The minimum expectation selection problem
Authors: David Eppstein, George S. Lueker
Venue: Random Structures Algorithms (2002)

We define the min-min expectation selection problem (resp. max-min expectation selection problem) to be that of selecting k out of n given discrete probability distributions, to minimize (resp. maximize) the expectation of the minimum value resulting when independent random variables are drawn from the selected distributions. We assume each distribution has finitely many atoms. Let d be the number of distinct values in the support of the distributions. We show that if d is a constant greater than 2, the min-min expectation problem is NP-complete but admits a fully polynomial time approximation scheme. For d an arbitrary integer, it is NP-hard to approximate the min-min expectation problem within any constant approximation factor. The max-min expectation problem is polynomially solvable for constant d; we leave open its complexity for variable d. We also show similar results for binary selection problems in which we must choose one distribution from each of n pairs of distributions.
Algorithms for Separable Nonlinear Resource Allocation Problems
Authors: Muralidharan S. Kodialam, Hanan Luss
Venue: Operations Research (1998)

We consider a simple resource allocation problem with a single resource constraint. The objective function is composed of separable, convex performance functions, one for each activity. Likewise, the constraint has separable, convex resource-usage functions, one for each activity. The objective is to minimize the sum of the performance functions, subject to satisfying the resource constraint and nonnegativity constraints. This problem extends the well-studied problem in which the resource constraint is linear. We present several algorithms to solve the problem. These algorithms extend approaches developed for the linearly constrained problem. They can readily solve large problems and find the optimal solution in a number of iterations that does not exceed the number of variables. We provide several examples for illustration purposes, present computational results, and highlight the similarities and differences among the algorithms.
Derivation of m-systems
Authors: D. Luyckx, J. A. Thas
Venue: European Journal of Combinatorics (2003)

We will discuss a way to construct new m-systems from known ones by replacing a number of elements of the m-system by a set of other subspaces covering the same points. Further, we investigate in which cases this method can be applied and we find new classes of 1-systems. In the last section, the semipartial geometries arising from 1-systems of W5(q) are studied and it is shown that some of the new 1-systems we have found yield new semipartial geometries.
Evolution of efficient swimming controllers for a simulated lamprey
Authors: Jimmy Or, John Hallam, David Willshaw, Auke Ijspeert
Venue: Proceedings of the seventh international conference on simulation of adaptive behavior on From animals to animats (2002)

This paper investigates the evolutionary design of efficient connectionist swimming controllers for a simulated lamprey. Efficiency is defined as the ratio of forward swimming speed to backward mechanical wave speed.Using the lamprey model proposed by Ekeberg (1993) and extending the work of Ijspeert et al. (1999) on evolving lamprey swimming central pattern generators (CPGs) through genetic algorithms (GAs), we investigate the space of possible neural configurations which satisfies the property of high swimming efficiency. Techniques are devised to measure efficiency at various swimming speeds. The measurements are incorporated into the fitness function of Ijspeert's original GA and efficient controllers are evolved. Interestingly, the best evolved controller not only is capable of swimming in a similar manner to the real lamprey, but also with the same efficiency (about 0.8). Moreover, it can exhibit a wide range of controllable speeds and efficiencies.
Complexity of Simulation Models: a Graph Theoretic Approach
Authors: Enver Yucesan, Lee Schruben
Venue: INFORMS Journal on Computing (1998)

In this article, we introduce complexity measures for simulation models. The framework of simulation graphs sets the context. A quantifiable measure of complexity is useful in an a priori evaluation of proposed simulation studies that must be completed within a specified budget. They can also be useful in classifying simulation models to obtain a thorough test bed of models to be used in simulation methodology research. The metrics introduced in this article have a rigorous theoretical, as well as empirical, grounding in software engineering. As such, simulation modeling and analysis represent a new area of application. Some surrogate measures of run time complexity are also developed. In particular, we provide estimates for the size of the future events list (or the pending event set). The proposed metrics are illustrated and compared through a limited set of examples. Limitations of the current approach as well as directions for future research are discussed.
Using a net to catch a mate: evolving CTRNNs for the dowry problem
Authors: Elio Tuci, Inman Harvey, Peter M. Todd
Venue: Proceedings of the seventh international conference on simulation of adaptive behavior on From animals to animats (2002)

Choosing one option from a sequence of possibilities seen one at a time is a common problem facing agents whenever resources, such as mates or habitats, are distributed in time or space. Optimal algorithms have been developed for solving a form of this sequential search task known as the Dowry Problem (finding the highest dowry in a sequence of 100 values); here we explore whether continuous time recurrent neural networks (CTRNNs) can be evolved to perform adaptively in Dowry Problem scenarios, as an example of minimally cognitive behavior [Beer, 1996]. We show that even 4-neuron CTRNNs can successfully solve this sequential search problem, and we offer some initial analysis of how they can achieve this feat.
Post global routing RLC crosstalk budgeting
Authors: Jinjun Xiong, Jun Chen, James Ma, Lei He
Venue: Proceedings of the 2002 IEEE/ACM international conference on Computer-aided design (2002)

Existing layout optimization methods often assume a set of interconnects with given RLC crosstalk bounds in a routing region. RLC crosstalk bound partitioning is critical for effectively applying these methods at the full-chip level. In this paper, we develop an optimal crosstalk budgeting scheme based on linear programming (LP) formulation, and apply it to shield insertion and net ordering at the full-chip level. Experiment results show that compared to the best alternative approach, the LP based method reduces the total routing area by up to 7.61% and also uses less runtime. To the best of our knowledge, this is the first in-depth work that studies the RLC crosstalk budgeting problem.
Panel: projects in database courses
Authors: Catherine Ricardo, Elizabeth Adams, Don Goelman, Mary Ann Robbert
Venue: Journal of Computing Sciences in Colleges (2003)

While the pedagogical importance of the group project is well documented and fairly adequately discussed in computer and information science and software engineering in general (e.g., [1], [2]), the focus of this panel session will be the specific considerations of using projects in database courses. Panelists will discuss their experiences in assigning a variety of projects in both the undergraduate and graduate level database courses. Topics include variations in problem scope and content, deliverables required, database management system used, workgroup size (individual or group), and assessments used to evaluate student work.
Simulating the Control of a Heterosexual HIV Epidemic in a Severely Affected East African City
Authors: Robert S. Bernstein, David C. Sokal, Steven T. Seitz, Bertran Auvert, John Stover, Warren Naamara
Venue: Interfaces (1998)

We compared three intervention strategies for preventing heterosexual transmission of the human immunodeficiency virus (HIV) using deterministic and stochastic models to simulate the epidemic of acquired immunodeficiency syndromes (AIDS). We estimated demographic, biological, and behavioral parameters for a severely affected east African city early in the epidemic, and used these parameter values in computing the spread of HIV under five scenarios: (1) a baseline scenario with no public health interventions; three single-intervention scenarios with strategies to (2) reduce the number and rate of change of sex partners, (3) increase condom use, or (4) improve treatment of sexually transmitted diseases (STD); and a (5) combined-intervention scenario. The rankings were the same in both models-decreasing partner change was most effective, followed by condom use and STD treatment. Combined interventions were more effective than single interventions. They interacted to produce impacts that varied with the trajectory of the epidemic at the onset of the interventions. Their timely, targeted, and sustained implementation appears critical to slow the epidemic significantly.
The relativistic and direct solar radiation pressure effects on an axially symmetric spacecraft. I. the Hamiltonian and the canonical equations of motion
Authors: M. I. El-Saftawy, A. A. El-Enna
Venue: Applied Mathematics and Computation (2002)

The effects of direct solar radiation pressure (SRP) and Earth oblateness in the post-Newtonian potential (PN) approximation on an Earth artificial satellite are investigated. The potential of the oblate Earth is limited to the principal term and the second zonal harmonic. The model of the satellite is adopted to be an axially symmetric body plus an axially symmetric antenna emitting or receiving radio beam. The attitude of the satellite is assumed stabilized such that the axis of the symmetric body is along the tangent to the orbit. The Hamiltonian of the system is developed in terms of the Delaunay elements augmented so as to remove the explicit time dependence, due to the mean longitude of the Sun. The canonical equations of motion are formed retaining terms up to O(J24) so as to retain the terms arising from the coupling between SRP and the oblateness PN terms.
Software project management audits-update and experience report
Authors: James McDonald
Venue: Journal of Systems and Software (2002)

This paper describes software project management audits as they have been defined in the literature. It outlines the motivation for conducting such audits routinely, which differs markedly from earlier recommendations in the literature and outlines how an audit can be conducted efficiently, from both the points of view of the software project manager and the auditing team, using procedures that have not been previously published. Finally, it provides some data on concerns that were found during several audits in which the author has participated and recommends, based on the data, what issues project managers and project management auditors should focus on when planning projects and conducting audits in the future.
CHI '03 extended abstracts on Human factors in computing systems
Venue: Conference on Human Factors in Computing Systems (2003)

1983: The first CHI called CHI - computers just processed data and Human-Computer Interaction (HCI) just supported users in their work tasks.Twenty years on, broadband servers and mobile devices now outnumber desktop office machines. With them come joy, persuasion, outrage, delight, faith, campaigns, satire, fun, learning, identity, communities, and passion. Now, increasingly, we interact to be, not just to do. Interaction no longer just changes things, it changes people. HCI is headed for New Horizons.CHI 2003 recognised this sea of change in HCI and addressed all forms of interactive digital communication, with a focus on three special areas: mass communication and interaction, e-learning, and emotion. Many presentations addressed these special areas. Still, CHI 2003 has not abandoned established HCI for New Horizons! Everything you'd expect to find in a CHI conference is still here.These Conference Proceedings contain the papers accepted for presentation at CHI 2003. Competition was fierce. 470 submissions were received, and 75 were accepted. Many of these accepted papers address the challenge of supportive effective and enjoyable communication via interactive digital media.A CD containing the extended abstracts for short talks, demonstrations, design and usability in practice papers, special interest group descriptions, interactive posters, student posters and doctoral consortiumpresentations accompanies these proceedings. Video figures and demonstrations are provided on an additional DVD. These complete the record of CHI 2003 as the meeting place for an inclusive community, The CHI conference is the annual gathering of the world's HCI community. There is something for everyone. Students, researchers, professionals, and educators are spoiled for choice.
Packing cycles in graphs, II
Authors: Guoli Ding, Zhenzhen Xu, Wenan Zang
Venue: Journal of Combinatorial Theory Series B (2003)

A graph G packs if for every induced subgraph H of G, the maximum number of vertex-disjoint cycles in H is equal to the minimum number of vertices whose deletion from H results in a forest. The purpose of this paper is to characterize all graphs that pack.
Analysis of linear systems with fuzzy parametric uncertainty
Authors: J. Bondia, J. Picó
Venue: Fuzzy Sets and Systems (2003)

In this paper the problem of determining the stability margin of a linear system with fuzzy parametric uncertainty is addressed. This kind of systems arise when the exact value of a process parameter is not available, but an estimation of the value is given by an expert ("more or less 5"). As the α-cut representation of a fuzzy number is a functional interval, interval analysis shows to be a suitable tool to deal with fuzziness. Based on the Argoun's stability test for interval systems, a new methodology, with a natural graphical interpretation, is presented. An independent confidence degree for every coefficient is considered, allowing a clear understanding on how each coefficient affects stability. An analysis on how precise one should be on some coefficients to allow more uncertainty on others can be carried out. A comparison with Tsypkin-Polyak plot is also presented.
Teaching the history of computer science
Authors: Trevis J. Rothwell
Venue: Ubiquity (2002)

Students who are truly interested in computer science would enjoy learning about those programmers who went before them, and how they overcame their difficulties.
The logical format of a floppy disk
Authors: S. L. Tuohy
Venue: Journal of Computing Sciences in Colleges (2002)

The logical layout of a floppy disk includes the boot sector, FAT (File Allocation Table), root Directory and Data region where the files and sub-directories are stored. All of these areas can be investigated with the program DEBUG.EXE which can be located using the Find command of Windows. This exercise can make the File System chapter from the Operating System's Course have so much more meaning. To illustrate the various regions of the disk, the Debug load(l), write(w), enter(e), display(d) in hexadecimal and quit(q) commands will be used.
Toward an optimization-driven framework for designing and generating realistic Internet topologies
Authors: David Alderson, John Doyle, Ramesh Govindan, Walter Willinger
Venue: ACM SIGCOMM Computer Communication Review (2003)

We propose a novel approach to the study of Internet topology in which we use an optimization framework to model the mechanisms driving incremental growth. While previous methods of topology generation have focused on explicit replication of statistical properties, such as node hierarchies and node degree distributions, our approach addresses the economic tradeoffs, such as cost and performance, and the technical constraints faced by a single ISP in its network design. By investigating plausible objectives and constraints in the design of actual networks, observed network properties such as certain hierarchical structures and node degree distributions can be expected to be the natural by-product of an approximately optimal solution chosen by network designers and operators. In short, we advocate here essentially an approach to network topology design, modeling, and generation that is based on the concept of Highly Optimized Tolerance (HOT). In contrast with purely descriptive topology modeling, this opens up new areas of research that focus on the causal forces at work in network design and aim at identifying the economic and technical drivers responsible for the observed large-scale network behavior. As a result, the proposed approach should have significantly more predictive power than currently pursued efforts and should provide a scientific foundation for the investigation of other important problems, such as pricing, peering, or the dynamics of routing protocols.
Transience of peers & streaming media
Authors: Mayank Bawa, Hrishikesh Deshpande, Hector Garcia-Molina
Venue: ACM SIGCOMM Computer Communication Review (2003)

Application level multicast schemes have traditionally been evaluated with respect to the efficiency penalties incurred in migrating the multicast functionality from the network layer to the application layer. We argue that the current performance measures, and therefore design strategies, are incomplete as they do not consider transience of peers. The routers in application level multicast systems are participant clients, and not infrastructure units. As such, the assumptions on the behavior of these application routers are significantly different from the infrastructure routing units that traditional research has dealt with, especially in a peer-to-peer setting where peers are multi-use and the management is decentralized. we argue that the transience in peer behavior has implications on end-performance enabled. We outline a design philosophy that seeks to separate policy decisions in handling peer behavior from the end-application at a basic infrastructural peering layer. As a proof of concept, we have implemented a peering layer prototype, which is available for download.
A MINSAT Approach for Learning in Logic Domains
Authors: Giovanni Felici, Klaus Truemper
Venue: INFORMS Journal on Computing (2002)

This paper describes a method for learning logic relationships that correctly classify a given data set. The method derives from given logic data certain minimum cost satisfiability problems, solves these problems, and deduces from the solutions the desired logic relationships. Uses of the method include data mining, learning logic in expert systems, and identification of critical characteristics for recognition systems. Computational tests have proved that the method is fast and effective.
Modal interactions in a Bickley jet: comparison of theory with direct numerical simulation
Authors: R. Mallier, M. Haslam
Venue: Mathematics and Computers in Simulation (2003)

This study is concerned with three-dimensional transition in plane wakes and jets. Nonlinear stability theory has predicted that interactions between different instability modes can play an important role in that transition. In this paper, we consider interactions between varicose and sinuous oblique disturbances in the Bickley jet, using both nonlinear stability theory (in its nonlinear critical layer form) and direct numerical simulation using a spectral method. We will first present an overview of the nonlinear stability theory which indicates that a (nonlinear) interaction between the modes should occur, and then present simulations that appear to support the theory.