ppxscal/embedding_network huggingface dataset:
Convergence of a Class of Inexact Interior-Point Algorithms for Linear Programs
Authors: Roland W. Freund, Florian Jarre, Shinji Mizuno
Venue: Mathematics of Operations Research (1999)

We present a convergence analysis for a class of inexact infeasible-interior-point methods for solving linear programs. The main feature of inexact methods is that the linear systems defining the search direction at each interior-point iteration need not be solved to high accuracy. More precisely, we allow that these linear systems are only solved to a moderate accuracy in the residual, but no assumptions are made on the accuracy of the search direction in the search space. In particular, our analysis does not require that feasibility is maintained even if the initial iterate happened to be a feasible solution of the linear program. We also present a few numerical examples to illustrate the effect of using inexact search directions on the number of interior-point iterations.
On Embeddings of the Flag Geometries of Projective Planesin Finite Projective Spaces
Authors: Joseph A. Thas, Hendrik Van Maldeghem
Venue: Designs, Codes and Cryptography (1999)

The flag geometry \Gamma=(\cP,\cL,\op) of a finite projective plane \Pi of order s is the generalized hexagon of order (s,1) obtained from \Pi by putting \cP equal to the set of all flags of\Pi , by putting \cL equal to the set of all points and lines of \Pi and where \op is the natural incidence relation (inverse containment), i.e.,\Gamma is the dual of the double of \Pi in the sense of Van Maldeghem Mal:98. Then we say that \Gamma is fully and weakly embedded in the finite projective space \PG(d,q) if \Gamma is a subgeometry of the natural point-line geometry associated with \PG(d,q), if s=q, if the set of points of \Gamma generates \PG(d,q), and if the set of points of \Gamma not opposite any given point of \Gamma does not generate \PG(d,q). Preparing the classification of all such embeddings, we construct in this paper the classical examples, prove some generalities and show that the dimension d of the projective space belongs to \{6,7,8\}.
Linear approximation of planar spatial databases using transitive-closure logic
Authors: Floris Geerts, Bart Kuijpers
Venue: Proceedings of the nineteenth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems (2000)

We consider spatial databases in the plane that can be defined by polynomial constraint formulas. Motivated by applications in geographic information systems, we investigate linear approximations of spatial databases and study in which language they can be expressed effectively. Specifically, we show that they cannot be expressed in the standard first-order query language for polynomial constraint databases but that an extension of this first-order language with transitive closure suffices to express the approximation query in an effective manner. Furthermore, we introduce an extension of transitive-closure logic and show that this logic is complete for the computable queries on linear spatial databases. This result together with our first result implies that this extension of transitive-closure logic can express all computable topological queries on arbitrary spatial databases in the plane.
Data mining on an OLTP system (nearly) for free
Authors: Erik Riedel, Christos Faloutsos, Gregory R. Ganger, David F. Nagle
Venue: ACM SIGMOD Record (2000)

This paper proposes a scheme for scheduling disk requests that takes advantage of the ability of high-level functions to operate directly at individual disk drives. We show that such a scheme makes it possible to support a Data Mining workload on an OLTP system almost for free: there is only a small impact on the throughput and response time of the existing workload. Specifically, we show that an OLTP system has the disk resources to consistently provide one third of its sequential bandwidth to a background Data Mining task with close to zero impact on OLTP throughput and response time at high transaction loads. At low transaction loads, we show much lower impact than observed in previous work. This means that a production OLTP system can be used for Data Mining tasks without the expense of a second dedicated system. Our scheme takes advantage of close interaction with the on-disk scheduler by reading blocks for the Data Mining workload as the disk head &ldquo;passes over&rdquo; them while satisfying demand blocks from the OLTP request stream. We show that this scheme provides a consistent level of throughput for the background workload even at very high foreground loads. Such a scheme is of most benefit in combination with an Active Disk environment that allows the background Data Mining application to also take advantage of the processing power and memory available directly on the disk drives.
Turtlemania: a math game in a distributed environment
Authors: David Clipsham, Brett Huffman, Joe Meissell, Mario Guimaraes
Venue: ACM SIGCUE Outlook (1999)

This paper is divided into four sections. First an introduction describes the basic goals of the educational math game and the environment chosen. The second section describes the software, showing pictures of the teacher interface (Figure 1) and the Student Interface (Figures 2 and 3). The third section describes the initial classroom experiments introducing the software to K-3 public school teachers and children from Pre-K to 6th grade. The last section presents the preliminary conclusions from using the software and how this type of framework could be used for other educational software.
Strategies for success in parallel simulation applications (keynote speech)
Authors: Frederick Wieland
Venue: Proceedings of the fourteenth workshop on Parallel and distributed simulation (2000)

While the PADS community has traditionally focused on&mdash;and done a greater job with&mdash;the technical aspects of developing simulations that run fast and can be connected to other simulations, it has paid little or no attention to the overall strategies required to produce a marketable, useful, and successful parallel simulation. This lack of market focus has led to many fears of the demise of the PADS community, complaints of its lack of general acceptance by the broader simulation community, and predictions that it will become merely another venue for simulation interconnections. These fears, complaints, and predictions are unnecessary. There are several examples of successful parallel simulations&mdash;in domains as far apart as aviation modeling and wargames. What can we learn from their successes? How can we translate their general acceptance into other parallel simulation domains? Are there market opportunities that we are missing? In short, what is the parallel simulation community lacking, and what does it need to do in order to be more successful? The purpose of this talk is to begin a discussion on the answers to these questions (as opposed to definitively answering them). We will draw on numerous examples of successful applications, and make some concrete suggestions for furthering the community.
A Customer-to-carrier Gateway for Multiple Services
Authors: Elizabeth D. Zeisler, Daniel H. Bolton, GordonB. H. Jones
Venue: International Journal of Network Management (1996)

This paper describes a customer-to-carrier prototype, based on a protocol-independent interface specification and the OMNIPoint Network Management Forum service management concept.
Learning Coordination Strategies for Cooperative Multiagent Systems
Authors: F. Ho, M. Kamel
Venue: Machine Learning (1998)

A central issue in the design of cooperative multiagent systems is how to coordinate the behavior of the agents to meet the goals of the designer. Traditionally, this had been accomplished by hand-coding the coordination strategies. However, this task is complex due to the interactions that can take place among agents. Recent work in the area has focused on how strategies can be learned. Yet, many of these systems suffer from convergence, complexity and performance problems. This paper presents a new approach for learning multiagent coordination strategies that addresses these issues. The effectiveness of the technique is demonstrated using a synthetic domain and the predator and prey pursuit problem.
Finding Subsets Maximizing Minimum Structures
Authors: Magnús M. Halldórsson, Kazuo Iwano, Naoki Katoh, Takeshi Tokuyama
Venue: SIAM Journal on Discrete Mathematics (1999)

We consider the problem of finding a set of k vertices in a graph that are in some sense remote. Stated more formally, given a graph G and an integer k, find a set P of k vertices for which the total weight of a minimum structure on P is maximized. In particular, we are interested in three problems of this type, where the structure to be minimized is a spanning tree ({\sc Remote-MST}), Steiner tree, or traveling salesperson tour.We study a natural greedy algorithm that simultaneously approximates all three problems on metric graphs. For instance, its performance ratio for {\sc Remote-MST} is exactly 4, while this problem is NP-hard to approximate within a factor of less than 2. We also give a better approximation for graphs induced by Euclidean points in the plane, present an exact algorithm for graphs whose distances correspond to shortest-path distances in a tree, and prove hardness and approximability results for general graphs.
Improved Diffuse Reflection Models for Computer Vision
Authors: Lawrence B. Wolff, Shree K. Nayar, Michael Oren
Venue: International Journal of Computer Vision (1998)

There are many computational vision techniques that fundamentally rely upon assumptions about the nature of diffuse reflection from object surfaces consisting of commonly occurring nonmetallic materials. Probably the most prevalent assumption made about diffuse reflection by computer vision researchers is that its reflected radiance distribution is described by the Lambertian model, whether the surface is rough or smooth. While computationally and mathematically a relatively simple model, in physical reality the Lambertian model is deficient in accurately describing the reflected radiance distribution for both rough and smooth nonmetallic surfaces. Recently, in computer vision diffuse reflectance models have been proposed separately for rough, and, smooth nonconducting dielectric surfaces each of these models accurately predicting salient non-Lambertian phenomena that have important bearing on computer vision methods relying upon assumptions about diffuse reflection. Together these reflectance models are complementary in their respective applicability to rough and smooth surfaces. A unified treatment is presented here detailing important deviations from Lambertian behavior for both rough and smooth surfaces. Some speculation is given as to how these separate diffuse reflectance models may be combined.
Ranking Strategies for Navigation Based Query Formulation
Authors: F. C. Berger, P. Van Bommel, Th. P. Van Der Weide
Venue: Journal of Intelligent Information Systems (1999)

Navigating through a hypermedia retrieval system bears the problem of selecting an item from a large number of options available to continue the trajectory. Ranking these options according to some criterion is a method to ease the task of navigation. A number of ranking strategies have already been proposed. This paper presents a formalization of the concept of ranking, and of the aforementioned strategies. Furthermore we propose two strategies allowing a personalized approach to ranking.
Timewarp rigid body simulation
Authors: Brian Mirtich
Venue: Proceedings of the 27th annual conference on Computer graphics and interactive techniques (2000)

The traditional high-level algorithms for rigid body simulation work well for moderate numbers of bodies but scale poorly to systems of hundreds or more moving, interacting bodies. The problem is unnecessary synchronization implicit in these methods. Jefferson's timewarp algorithm [22] is a technique for alleviating this problem in parallel discrete event simulation. Rigid body dynamics, though a continuous process, exhibits many aspects of a discrete one. With modification, the timewarp algorithm can be used in a uniprocessor rigid body simulator to give substantial performance improvements for simulations with large numbers of bodies. This paper describes the limitations of the traditional high-level simulation algorithms, introduces Jefferson's algorithm, and extends and optimizes it for the rigid body case. It addresses issues particular to rigid body simulation, such as collision detection and contact group management, and describes how to incorporate these into the timewarp framework. Quantitative experimental results indicate that the timewarp algorithm offers significant performance improvements over traditional high-level rigid body simulation algorithms, when applied to systems with hundreds of bodies. It also helps pave the way to parallel implementations, as the paper discusses.
Oscillation Theory and Numerical Solution of Sixth Order Sturm--Liouville Problems
Authors: Leon Greenberg, Marco Marletta
Venue: SIAM Journal on Numerical Analysis (1998)

Following earlier work on fourth order problems, we develop a shooting method to approximate the eigenvalues of sixth order Sturm--Liouville problems using a spectral function N(\lam) which counts the number of eigenvalues less than $\lam$. This requires an "oscillation" count obtained from certain solutions of the differential equation, and we develop explicit algorithms for obtaining the exact oscillation count when the coefficients in the differential equation are piecewise constant. This work requires the use of a homotopy to simplify the problems under scrutiny. We also show that the Riccati-like variables in which the differential equation is integrated (for reasons of stability) satisfy a linear system of differential equations, and we exploit this to integrate the equation by computing a matrix exponential.
A subdivision-based algorithm for the sparse resultant
Authors: John F. Canny, Ioannis Z. Emiris
Venue: Journal of the ACM (JACM) (2000)

Multivariate resultants generalize the Sylvester resultant of two polynomials and characterize the solvability of a polynomial system. They also reduce the computation of all common roots to a problem in linear algebra. We propose a determinantal formula for the sparse resultant of an arbitrary system of n + 1 polynomials in n variables. This resultant generalizes the classical one and has significantly lower degree for polynomials that are sparse in the sense that their mixed volume is lower than their B&eacute;zout number. Our algorithm uses a mixed polyhedral subdivision of the Minkowski sum of the Newton polytopes in order to construct a Newton matrix. Its determinant is a nonzero multiple of the sparse resultant and the latter equals the GCD of at most n + 1 such determinants. This construction implies a restricted version of an effective sparse Nullstellensatz. For an arbitrary specialization of the coefficients, there are two methods that use one extra variable and yield the sparse resultant. This is the first algorithm to handle the general case with complexity polynomial in the resultant degree and simply exponential in n. We conjecture its extension to producing an exact rational expression for the sparse resultant.
QSplat: a multiresolution point rendering system for large meshes
Authors: Szymon Rusinkiewicz, Marc Levoy
Venue: Proceedings of the 27th annual conference on Computer graphics and interactive techniques (2000)

Advances in 3D scanning technologies have enabled the practical creation of meshes with hundreds of millions of polygons. Traditional algorithms for display, simplification, and progressive transmission of meshes are impractical for data sets of this size. We describe a system for representing and progressively displaying these meshes that combines a multiresolution hierarchy based on bounding spheres with a rendering system based on points. A single data structure is used for view frustum culling, backface culling, level-of-detail selection, and rendering. The representation is compact and can be computed quickly, making it suitable for large data sets. Our implementation, written for use in a large-scale 3D digitization project, launches quickly, maintains a user-settable interactive frame rate regardless of object complexity or camera position, yields reasonable image quality during motion, and refines progressively when idle to a high final image quality. We have demonstrated the system on scanned models containing hundreds of millions of samples.
A replicated assessment and comparison of common software cost modeling techniques
Authors: Lionel C. Briand, Tristen Langley, Isabella Wieczorek
Venue: Proceedings of the 22nd international conference on Software engineering (2000)

Delivering a software product on time, within budget, and to an agreed level of quality is a critical concern for many software organizations. Underestimating software costs can have detrimental effects on the quality of the delivered software and thus on a company's business reputation and competitiveness. On the other hand, overestimation of software cost can result in missed opportunities to funds in other projects. In response to industry demand, a myriad of estimation techniques has been proposed during the last three decades. In order to assess the suitability of a technique from a diverse selection, its performance and relative merits must be compared.The current study replicates a comprehensive comparison of common estimation techniques within different organizational contexts, using data from the European Space Agency. Our study is motivated by the challenge to assess the feasibility of using multi-organization data to build cost models and the benefits gained from company-specific data collection. Using the European Space Agency data set, we investigated a yet unexplored application domain, including military and space projects. The results showed that traditional techniques, namely, ordinary least-squares regression and analysis of variance outperformed Analogy-based estimation and regression trees. Consistent with the results of the replicated study no significant difference was found in accuracy between estimates derived from company-specific data and estimates derived from multi-organizational data.
Web-accessible network management tools
Authors: Nathan J. Muller
Venue: International Journal of Network Management (1997)

Web-based delivery of management information is becoming a key strategic element in corporate development. This article evaluates various proprietory web-based management tools, in light of recently proposed industry standards &copy; 1997 John WileWiley & Sons, Ltd.
Analytic Controllability of a Linear Hybrid System
Authors: Brice Allibert
Venue: SIAM Journal on Control and Optimization (1999)

In this paper, we consider a boundary control problem for a model of a fluid-structure hybrid system. This model has been introduced by Micu and Zuazua in connection with the works of Banks et al. They have given explicit values for the spectral data in [S. Micu and E. Zuazua, SIAM J. Math. Anal., 29 (1998), pp. 967--1001] and results for the control problem in [S. Micu and E. Zuazua, SIAM J. Control. Optim., 35 (1997), pp. 1614--1637]. In the latter paper, they use variable separation and Ingham inequalities to prove an observation estimate that implies, through the Hilbert uniqueness method, that initial data can be controlled within finite time. This paper improves these results by using a stronger form of Ingham inequality for low frequencies. Indeed, we prove that any analytic function is controlled in a finite time whose dependence on the analyticity can be sharply estimated.
A Log-Domain CMOS Transcapacitor: Design, Analysis and Applications
Authors: Eric Fragnière Eric Vittoz, André van Schaik
Venue: Analog Integrated Circuits and Signal Processing (2000)

We present in this paper the CMOS implementation of a transcapacitor working in the log-domain. This circuit integrates a differential input current into an output pseudo-voltage, which is similar to the compressed voltage used as the internal variable in companding filters. This log-domain transcapacitor is compatible with pseudo-conductances implemented with a single transistor. The pseudo-transcapacitor circuit is analyzed and a collection of log-domain reactive components and small circuits using it is proposed.
Timer-driven database triggers and alerters: semantics and a challenge
Authors: Eric N. Hanson, Lloyd X. Noronha
Venue: ACM SIGMOD Record (1999)

This paper proposes a simple model for a timer-driven triggering and alerting system. Such a system can be used with relational and object-relational databases systems. Timer-driven trigger systems have a number of advantages over traditional trigger systems that test trigger conditions and run trigger actions in response to update events. They are relatively easy to implement since they can be built using a middleware program that simply runs SQL statements against a DBMS. Also, they can check certain types of conditions, such as &ldquo;a value did not change&rdquo; or a &ldquo;a value did not change by more than 10% in six months.&rdquo; Such conditions may be of interest for a particular application, but cannot be checked correctly by an event-driven trigger system. Also, users may be perfectly happy being notified once a day, once a week, or even less often of certain conditions, depending on their application. Timer triggers are appropriate for these users. The semantics of timer triggers are defined here using a simple procedure. Timer triggers are meant to complement event-driven triggers, not replace them. We challenge the database research community to developed alternate algorithms and optimizations for processing timer triggers, provided that the semantics are the same as when using the simple procedure presented here.
Extended Linial Hyperplane Arrangements for Root Systems and a Conjecture of Postnikov and Stanley
Authors: Christos A. Athanasiadis
Venue: Journal of Algebraic Combinatorics: An International Journal (1999)

A hyperplane arrangement is said to satisfy the &ldquo;Riemann hypothesis&rdquo; if all roots of its characteristic polynomial have the same real part. This property was conjectured by Postnikov and Stanley for certain families of arrangements which are defined for any irreducible root system and was proved for the root system A_n &minus; 1. The proof is based on an explicit formula [1, 2, 11] for the characteristic polynomial, which is of independent combinatorial significance. Here our previous derivation of this formula is simplified and extended to similar formulae for all but the exceptional root systems. The conjecture follows in these cases.
Improving Network Operations With Intelligent Agents
Authors: Nathan J. Muller
Venue: International Journal of Network Management (1997)

Automating network and system management tasks has never been easier, since the advent of intelligent agents. This article describes the uses and advantages of intelligent agents, to identify and resolve problems locally, instead of dispatching technicians to remote locations, which is both expensive and time&hyphen;consuming. &copy; 1997 John Wiley Sons, Ltd.