ppxscal/embedding_network huggingface dataset:
SOR as a Preconditioner
Authors: M. A. DeLong, J. M. Ortega
Venue:  (1994)

We show by experimental results on some convection-diffusion type equations that the SOR iteration may be a promising preconditioner in conjunction with the GMRES method. Our results indicate that it is critical to take several Gauss-Seidel or SOR iterations, rather than just one, and that at least a factor of two improvement over Gauss-Seidel can be expected with a reasonable approximation to the optimal omega. This approximation must be on the low side of the optimum, however, as an omega only slightly too large can lead to no convergence. We also show that the red/black ordering leads to no degradation and is usually slightly beneficial. Thus, we expect good parallel results although the current experiments are only on a serial machine. Limited experiments with BiCGSTAB do not show similar improvements for Gauss-Seidel preconditioning although a suitable omega can give a factor of two speedup.
On the Invariance of the Interpolation Points of the Discrete l1-approximation
Authors: Uri Ascher
Venue:  (1977)

Consider discrete $l_{1}$-approximations to a data function $f$, on some finite set of points $X$, by functions from a linear space of dimension $m > \infty$. It is known that there always exists a best approximation which interpolates $f$ on a subset of $m$ points of $X$. This does not generally hold for the ``continuous'''' $L_{1}$-approximation on an interval, as we show by means of an example. We investigate the invariance of the interpolation points of the discrete $l_{1}$-approximation under a change in the approximated function. Conditions are given, under which the interpolant to a function $g$ on a set of ``best $l_{1}$ points'''' of a function $f$ is a best $l_{1}$-approximant to $g$. Additional results are then obtained for the particular case of spline $l_{1}$-approximation.
Turing''s Test and Conscious Thought
Authors: Donald Michie
Venue:  (1992)

Over 40 years ago, A. M. Turing proposed a test for intelligence in machines. Based as it is, solely on an examinee''s verbal responses, the Test misses some important components of human thinking. To bring these manifestations within its scope, the Turing Test would require substantial extension. Advances in the application of AI methods in the design of improved human-computer interfaces are now focusing attention on machine models of thought and knowledge from the altered standpoint of practical utility.
Numerical Criterion for the Stabilization of Steady States of the Navier-Stokes Equations
Authors: C. Cao, I. G. Kevrekidis, E. S. Titi
Venue:  (1999)

This paper introduces an explicit numerical criterion for the stabilization of steady state solutions of the Navier-Stokes equations (NSE) with linear feedback control. Given a linear feedback controller that stabilizes a steady state solution to the closed-loop standard Galerkin (or nonlinear Galerkin) NSE discretization, it is shown that, if the number of modes involved in the computation is large enough, this controller stabilizes a nearby steady state of the closed-loop NSE. We provide an explicit estimate, in terms of the physical parameters, for the number of modes required in order for this criterion to hold. Moreover, we provide an estimate for the distance between the stabilized numberical steady state and the actually stabilized steady state of the closed-loop Navier-Stokes equations. More accurate approximation procedures, based on the concept of postprocessing the Galerkin results, are also presented. Allthe criterion conditions are imposed on the computed numerical solution, and no a priori knowledge is required about the steady state solution of the full PDE. This criterion holds for a large class of unbounded linear feedback operators and can be slightly modified to include certain nonlinear parabolic systems such as reaction-diffusion systems.
Scalable Database Support for Correlation and Fusion Algorithms
Authors: J. E. Barros, J. C. French
Venue:  (1993)

The process of extracting useful information from noisy sensor data is an important part of applications such as environmental analysis and military surveillance. Difficulties arise with analyzing the accuracy of the reports and in processing the total number of reports. Automated methods capable of handling noisy information from multiple sensors must be employed to assist the human analyst. This report investigates scalable database support for such systems. Region estimation and range retrieval techniques are employed to dramatically reduce retrieval and overall execution times.
ANATOMICALLY BASED MODELING
Authors: Jane Wilhelms, Allen VanGelder
Venue:  (1997)

We describe an improved, anatomically based approach to modeling and animating animals. Underlying muscles, bones, and generalized tissue are modeled as triangle meshes or ellipsoids. Muscles are deformable discretized cylinders lying between fixed origins and insertions on specific bones. Default rest muscle shapes can be used, or the rest muscle shape can be designed by the user with a small set of parameters. Muscles automatically change shape as the joints move. Skin is generated by voxelizing the underlying components, filtering, and extracting a polygonal isosurface. Isosurface skin vertices are associated with underlying components and move with them during joint motion. Skin motion is consistent with an elastic membrane model. All components are parameterized and can be reused on similar bodies with non-uniformly scaled parts. This parameterization allows a non-uniformly sampled skin to be extracted, maintaining more details at the head and extremities.
TRACKING DRIFTING CONCEPTS BY MINIMIZING DISAGREEMENTS
Authors: David P. Helmbold, Philip M. Long
Venue:  (1991)

In this paper we consider the problem of tracking a subset of a domain (called the *target*) which changes gradually over time. A single (unknown) probability distribution over the domain is used to generate random examples for the learning algorithm and measure the speed at which the target changes. We show that if the problem of minimizing the number of disagreements with a sample from among concepts in a class H can be approximated to within a factor k , then there is a simple tracking algorithm for H which can achieve a probability epsilon of making a mistake if the target movement rate is at most a constant times epsilon^{2}/(k(d+k) ln {1 over epsilon}), where d is the Vapnik-Chervonenkis dimension of H . Also, we show that if H is properly PAC-learnable, then there is an efficient (randomized) algorithm that with high probability approximately minimizes disagreements to within a factor of 7d+1, yielding an efficient tracking algorithm for H which tolerates drift rates up to a constant times epsilon^{2}/(d^2 ln {1 over epsilon}). In addition, we prove complementary results for the classes of halfspaces and axis-aligned hyperrectangles showing that the maximum rate of drift that any algorithm (even with unlimited computational power) can tolerate is a constant times epsilon^{2}/d.
Mapping concurrent applications onto architectural platforms
Authors: Andrew Mihal, Kurt Keutzer
Venue: Networks on chip (2003)

Embedded system designers are faced with an expanding array of challenges 1in both application and architecture design. One challenge is the task of modelling heterogeneous concurrent applications. Another is the task of finding a programming model for heterogeneous multiprocessor architectural platforms. Compounding each of these challenges is the task of implementing heterogeneous applications on heterogeneous architectures. We believe that the key problem underlying each of these challenges is the modelling of concurrency, and the key to modelling concurrency is to capture concurrent communication formally in models of computation. This chapter broadly outlines a disciplined approach to the design and implementation of communication structures in embedded applications. Our approach combines the Network-on-Chip paradigm with the models of computation paradigm. We use models of computation to capture the communication requirements of an application as well as to abstract the capabilities of a communication architecture. Then, application requirements and architectural capabilities are matched using a discipline based on Network-on-Chip principles. In this chapter we describe this approach and present a case study where a Click network routing application is implemented on a multiprocessor architecture using this discipline.
Which semantic web?
Authors: Catherine C. Marshall, Frank M. Shipman
Venue: Proceedings of the fourteenth ACM conference on Hypertext and hypermedia (2003)

Through scenarios in the popular press and technical papers in the research literature, the promise of the Semantic Web has raised a number of different expectations. These expectations can be traced to three different perspectives on the Semantic Web. The Semantic Web is portrayed as: (1) a universal library, to be readily accessed and used by humans in a variety of information use contexts; (2) the backdrop for the work of computational agents completing sophisticated activities on behalf of their human counterparts; and (3) a method for federating particular knowledge bases and databases to perform anticipated tasks for humans and their agents. Each of these perspectives has both theoretical and pragmatic entailments, and a wealth of past experiences to guide and temper our expectations. In this paper, we examine all three perspectives from rhetorical, theoretical, and pragmatic viewpoints with an eye toward possible outcomes as Semantic Web efforts move forward.
Subprogram Inlining: A Study of its Effects on Program Execution Time
Authors: Jack W. Davidson, Anne M. Holler
Venue:  (1989)

Equations representing the execution time performance on noninlined and inlined versions of a program have been developed. The accuracy of the equations'' description of inlined program execution time behavior was demonstrated on four computer systems. Using the equations, understanding of how certain factors influence the speed of inlined code was gained. Contrary to a number of published reports in the literature, the increased size of inlined code was not found to affect its execution time performance on demand-paged virtual memory machines. On such systems, neither the use of an inlining algorithm that includes program size constraints nor the substitution of interprocedural data flow analysis for inlining is warranted. A modest improvement in the caching and paging behavior of test programs'' inlined versions was also observed. Situations in which inlining was not beneficial, which were related to its interactions with register allocation, were characterized. Furthermore, investigation with the equations provided insights that can be of value to machine and compiler designers.
Parallel Algorithm for the Matrix Chain Product Problem
Authors: Artur Czumaj
Venue:  (1992)

This paper considers the problem of finding an optimal order of the multiplication chain of matrices. All parallel algorithms known use the dynamic programming approach and run in a polylogarithmic time using, in the best case, n ^6/log^6n processors. Our algorithm uses a different approach and reduces the problem to computing some recurrence on a tree. We show that this recurrence can be optimally solved which enables us to improve the parallel bound by a few factors. Our algorithm runs in O (log^3 n) time using n^2/log^3n processors on a CREW PRAM and O(log^2 n log log n ) time using n ^2/(log^2n log log n)processors on a CRCW PRAM. This algorithm solves also the problem of finding an optimal triangulation in a convex polygon. We show that for a monotone polygon this result can be even improved to get an O(log^2n) time and n processor algorithm on a CREW PRAM.
Vorticity Induced by a Moving Elliptic Belt
Authors: Calvin J. Ribbens, C. Y. Wang, Layne T. Watson, Kevin A. Alexander
Venue:  (1989)

The viscous flow inside an elliptic moving belt is studied using Newton''s method on a Hermite collocation approximation. The streamlines and especially the vorticity distribution are found for Reynolds number up to 1000 and aspect ratio up to five. For low Reynolds numbers vorticity diffuses from regions of high curvature. For high Reynolds numbers there exists a closed boundary layer and a core of constant vorticity. The core vorticity compares well with the estimation from the mean square law.
Tighter Lower Bounds on The Exact Complexity of String Matching
Authors: Richard Cole, Ramesh Hariharan, M. S. Paterson, U. Zwick
Venue:  (1993)

The paper considers the exact number of character comparisons needed to find all occurrences of a pattern of length m in a text of length n using on-line and general algorithms. For on-line algorithms, a lower bound of about (1 + 16/(7m + 16)) mod n character comparisons is obtained. For general algorithms, a lower bound of about (1+ 2/(m + 3)) mod n character comparisons is obtained. These lower bounds complement an on-line upper bound of about (1 + 8/(3m + 3)) mod n comparisons obtained recently by Cole and Hariharan. The lower bounds are obtained by finding patterns with interesting combinatorial properties. It is also shown that for some patterns off-line algorithms can be more efficient than on-line algorithms.
The Total Distance Measure for Virtual Path Layouts in ATM Networks,
Authors: D. Peleg, U. Pincas
Venue:  (2001)

This paper introduces and studies the total distance measure for virtual path layouts of ATM networks. We focus on the all-to-all and the one-to-all (broadcast) communication problems. The ATM network model is based on covering the network with simple virtual paths, under some constraints on the allowed load (i.e., the number of paths that can share an edge). Whereas former studies concerned the maximum hop count (namely, the number of edges traversed between the vertices that need to communicate) of the network, our interest here is in measuring the total hop count (namely, total distance ), or, alternatively, the average hop count. Basic results are established concerning the total distance parameter and its relation to the maximum hop count in some network types, mainly focusing on comparing the order of growth of the maximum hop count and the average hop count of these networks, assuming uniform communication requirements. Turning to arbitrary communication requirements, we present an algorithm for designing an optimal (minimal total distance) virtual path layout of an ATM network for general one-to-all requirements over the class of tree networks.
Interoperability of Parallel Systems: Running PVM Applications in the Legion Environment
Authors: Roger R. Harper
Venue:  (1995)

Parallel Programming systems based on loosely coupled networks of computers are becoming more and more popular. One of the more popular systems is Parallel Virtual Machine (PVM) which allows a user to think of a set of computers as a single parallel machine. The Legion project at the University of Virginia is another attempt to provide users with the illusion that a collection of computers is a single virtual machine. This report describes a software library that allows applications written for the PVM system to run in the Legion Environment. The report describes the design and development of the library, and compares the performance of the library, and PVM, on established benchmark applications. The ACM Portal is published by the Association for Computing Machinery. Copyright © 2010 ACM, Inc. Terms of Usage Privacy Policy Code of Ethics Contact Us Useful downloads: Adobe Acrobat QuickTime Windows Media Player Real Player
Metadata Management and Data Warehousing
Authors: Martin Staudt, Anca Vaduva, Thomas Vetterli
Venue:  (1999)

This report gives an overview of metadata management in general (Part I) and on the role of metadata for data warehousing (Part II). Because of the complexity and extensive applicability of metadata, a compact, precise definition of the notion may hardly be provided. Therefore, we explain metadata by illustrating the use and the forms it may take within various application areas. In the case of data warehousing, we present a classification of metadata along certain dimensions and we discuss significant aspects of metadata management that have to be considered for the construction of a data warehouse system. Furthermore, this report provides a comprehensive survey and analysis of the state of the art of metadata management in industry and research. The most important standards for representation and interchange of metadata, commercial products and research projects are presented and discussed (as far as the available information allows) for both, the general case and the particular case of data warehousing.
Soundness and Cut-Elimination in NaDSyL
Authors: Paul C. Gilmore
Venue:  (1997)

NaDSyL, a Natural Deduction based Symbolic Logic, like some earlier logics, is motivated by the belief that a confusion of use and mention is the source of the set theoretic paradoxes. However NaDSyL differs from the earlier logics in several important respects. "Truth gaps", as they have been called by Kripke, are essential to the consistency of the earlier logics, but are absent from NaDSyL; the law of the excluded middle is derivable for all the sentences of NaDSyL. But the logic has an undecidable elementary syntax, a departure from tradition that is of little importance, since the semantic tree presentation of the proof theory can incorporate the decision process for the elementary syntax. The use of the lambda calculus notation in NaDSyL, rather than the set theoretic notation of the earlier logics, reflects much more than a change of notation. For a second motivation for NaDSyL is the provision of a higher order logic based on the original term models of the lambda calculus rather than on the Scott models. These term models are the "natural" intepretation of the lambda calculus for the naive nominalist view that justifies the belief in the source of the paradoxes. They provide the semantics for the first order domain of the second order logic NaDSyL. The elementary and logical syntax or proof theory of NaDSyL is fully described, as well as its semantics. Semantic proofs of the soundness of NaDSyL with cut and of the completeness of NaDSyL without cut are given. That cut is a redundant rule follows form these results. Some applications of the logic are also described.
Learning Foraging Thresholds for Lizards
Authors: L. A. Goldberg, W. E. Hart, D. B. Wilson
Venue:  (1996)

This work gives a proof of convergence for a randomized learning algorithm that describes how anoles (lizards found in the Carribean) learn a foraging threshold distance. The model assumes that an anole will pursue a prey if and only if it is within this threshold of the anole''s perch. This learning algorithm was proposed by the biologist Roughgarden and his colleagues. They experimentally confirmed that this algorithm quickly converges to the foraging threshold that is predicted by optimal foraging theory. Our analysis provides an analytic confirmation that the learning algorithm converges to this optimal foraging threshold with high probability.
A Learning Algorithm for Structured Invariant Neural Networks
Authors: Sabine Kroner
Venue:  (1996)

Structured multi-layer feedforward neural networks gain more and more importance in speech and image processing applications. The characteristic of structured neural networks is that a-priori knowledge about the task to be performed is directly built into their architecture by the use of nodes with shared weight vectors. Usually these networks are trained with a modified backpropagation algorithm. However, due to the constraints on the weight vectors it is difficult to find suitable initialization values, and often the algorithm fails to converge. In this paper a new algorithm is proposed for the training of a structured feedforward neural network used for shift and rotation invariant pattern recognition. The algorithm works layerwise by minimizing a local optimization criterion. It is shown that the final value of the error function achieved with this algorithm is identical with the global minimum of the error function. Moreover the construction of the learning algorithm leads to definite convergence after one training cycle only.
Implementation of a Perfect Hash Function Scheme
Authors: Sanjeev Datta, Edward A. Fox
Venue:  (1989)

This report surveys the recent development in computing perfect hash functions, and in particular, closely examines an algorithm proposed by Thomas Sager. An implementation of that algorithm in C has been done to demonstrate and verify the behavior of the algorithm for various settings of parameters.
DESCRIPTIVE COMPLEXITY OF OPTIMIZATION AND COUNTING PROBLEMS (Ph.D. thesis)
Authors: Madhukar N Thakur
Venue:  (1992)

This thesis is about the descriptive complexity of two function classes, namely, NP optimization problems and #P counting problems. It is divided into two parts. In Part I we investigate NP optimization problems from a logical definability standpoint. We show that the class of optimization problems whose optimum is definable using first-order formulae coincides with the class of polynomially bounded NP optimization problems on finite structures. Next, we analyze the relative expressive power of various classes of optimization problems in this framework. We introduce an alternate approach to the logical definability of NP optimization problems by focusing on the expressibility of feasible solutions. We study the relationships between classes defined in these two frameworks. We identify sufficient syntactic conditions for approximability and isolate rich classes of approximate problems. Some of our results show that logical definability has different implications for NP maximization problems than it has for NP minimization problems, in terms of both expressive power and approximation properties. Regarding the relationship between approximability and logical definability, we show that, assuming P /= NP, it is undecidable to tell if a given first-order sentence defines an approximable optimization problem. Finally, we provide a machine-independent characterization of the NP ?= co-NP problem in terms of logical expressibility of the MAX CLIQUE problem. We conclude Part I by discussing some future directions in this line of research. In Part II, we give a logic based framework for defining counting problems and show that it exactly captures the problems in Valiant''s counting class #P. We study the expressive power of the framework under natural syntactic restrictions and show that some of the subclasses so obtained contain problems in #P with interesting computational properties. In particular, using syntactic conditions, we isolate a class of polynomial time computable #P problems, and also a class in which every problem is approximable by a polynomial time randomized algorithm. We show, under reasonable complexity theoretic assumptions, that it is undecidable to tell if a counting problem expressed in our framework is polynomial time computable or is approximable by a randomized polynomial time algorithm. This work sets the foundation for further study of the descriptive complexity of the class #P.
Concepts \& Methods for Database Design
Authors: Paul C. Gilmore
Venue:  (1987)

This report consists of drafts of chapters of a book prepared as course material for CSCI 404 at the University of British Columbia.