ppxscal/embedding_network huggingface dataset:
Efficient on-line communication in cellular networks
Authors: Ioannis Caragiannis, Christos Kaklamanis, Evi Papaioannou
Venue: Proceedings of the twelfth annual ACM symposium on Parallel algorithms and architectures (2000)

In this paper we consider communication issues arising in mobile networks that utilize Frequency Division Multiplexing (FDM) technology. In such networks, many users within the same geographical region can communicate simultaneously with other users of the network using distinct frequencies. The spectrum of available frequencies is limited; thus, efficient solutions to the frequency allocation and the call control problem are essential. In the frequency allocation problem, given users that wish to communicate, the objective is to minimize the required spectrum of frequencies so that communication can be established without signal interference. The objective of the call control problem is, given a spectrum of available frequencies and users that wish to communicate, to maximize the number of users served. We consider cellular, planar, and arbitrary network topologies. In particular, we study the on-line version of both problems using competitive analysis. For frequency allocation in cellular networks, we improve the best known competitive ratio upper bound of 3 achieved by the folklore Fixed Allocation algorithm, by presenting an almost tight competitive analysis for the greedy algorithm; we prove that its competitive ratio is between 2.429 and 2.5. For the call control problem, we present the first randomized algorithm that beats the deterministic lower bound of 3 achieving a competitive ratio of 2.934 in cellular networks. Our analysis has interesting extensions to arbitrary networks. Also, using Yao's Minimax Principle, we prove two lower bounds of 1.857 and 2.086 on the competitive ratio of randomized call control algorithms for cellular and arbitrary planar networks, respectively.
Chip-Firing and the Critical Group of a Graph
Authors: N. L. Biggs
Venue: Journal of Algebraic Combinatorics: An International Journal (1999)

A variant of the chip-firing game on a graph is defined. It is shown that the set of configurations that are stable and recurrent for this game can be given the structure of an abelian group, and that the order of the group is equal to the tree number of the graph. In certain cases the game can be used to illuminate the structure of the group.
Generating and reintegrating geospatial data
Authors: Robert F. Chavez
Venue: Proceedings of the fifth ACM conference on Digital libraries (2000)

The process of building a geospatial component to access existing materials in the Perseus Digital Library has raised interesting questions about the interaction between historical and geospatial data. The traditional methods of describing geographic features' names and locations do not provide a complete solution for historical data such as that in the Perseus Digital Library. Very often data sources for a spatial database must be created from the historical materials themselves.
Bounds for Dispersers, Extractors, and Depth-Two Superconcentrators
Authors: Jaikumar Radhakrishnan, Amnon Ta-Shma
Venue: SIAM Journal on Discrete Mathematics (2000)

We show that the size of the smallest depth-two $N$-superconcentrator is $$ \Theta(N\log^2 N/\log\log N). $$ Before this work, optimal bounds were known for all depths except two. For the upper bound, we build superconcentrators by putting together a small number of disperser graphs; these disperser graphs are obtained using a probabilistic argument. For obtaining lower bounds, we present two different methods. First, we show that superconcentrators contain several disjoint disperser graphs. When combined with the lower bound for disperser graphs of Kovari, S&oacute;s, and Tur&aacute;n, this gives an almost optimal lower bound of $\Omega( N (\log N/\log \log N)^2)$ on the size of $N$-superconcentrators. The second method, based on the work of Hansel, gives the optimal lower bound.The method of Kovari, S&oacute;s, and Tur&aacute;n can be extended to give tight lower bounds for extractors, in terms of both the number of truly random bits needed to extract one additional bit and the unavoidable entropy loss in the system. If the input is an $n$-bit source with min-entropy $k$ and the output is required to be within a distance of $\epsilon$ from uniform distribution, then to extract even one additional bit, one must invest at least $\log(n-k) + 2\log(1/\epsilon) - O(1)$ truly random bits; to obtain $m$ output bits one must invest at least $m-k+2\log(1/\epsilon)-O(1)$. Thus, there is a loss of $2\log(1/\epsilon)$ bits during the extraction. Interestingly, in the case of dispersers this loss in entropy is only about $\log\log (1/\epsilon)$.
Research and career development opportunities for meeting the challenges presented by the Human Genome project
Authors: Bettie J. Graham
Venue: ACM SIGBIO Newsletter (1999)

This paper describes research and career development programs supported by the National Human Genome Research Institute. These programs focus on training the next generation of scientists who have degrees in computer sciences, mathematics, physics, chemistry, engineering or related quantitative sciences and who wish to make a significant contribution to the Human Genome Project or to broader areas of genomic science.
The State of Elliptic Curve Cryptography
Authors: Neal Koblitz, Alfred Menezes, Scott Vanstone
Venue: Designs, Codes and Cryptography (2000)

Since the introduction of public-key cryptography by Diffie and Hellman in 1976, the potential for the use of the discrete logarithm problem in public-key cryptosystems has been recognized. Although the discrete logarithm problem as first employed by Diffie and Hellman was defined explicitly as the problem of finding logarithms with respect to a generator in the multiplicative group of the integers modulo a prime, this idea can be extended to arbitrary groups and, in particular, to elliptic curve groups. The resulting public-key systems provide relatively small block size, high speed, and high security. This paper surveys the development of elliptic curve cryptosystems from their inception in 1985 by Koblitz and Miller to present day implementations.
A Mechanically Checked Proof of a Multiprocessor Result via a Uniprocessor View
Authors: J. Strother Moore
Venue: Formal Methods in System Design (1999)

We describe a mechanically checked correctness proof for a system of n processes, each running a simple, non-blocking counter algorithm. We prove that if the system runs longer than 5n steps, the counter is increased. The theorem is formalized in applicative Common Lisp and proved with the ACL2 theorem prover. The value of this paper lies not so much in the trivial algorithm addressed as in the method used to prove it correct. The method allows one to reason accurately about the behavior of a concurrent, multiprocess system by reasoning about the sequential computation carried out by a selected process, against a memory that is changed externally. Indeed, we prove general lemmas that allow shifting between the multiprocess and uniprocess views. We prove a safety property using a multiprocess view, project the property to a uniprocess view, and then prove a global progress property via a local, sequential computation argument. Our uniprocessor view is a formal compositional semantics for a shared memory system.
Stabilized Finite Element Formulations for Shells in a Bending Dominated State
Authors: Dominique Chapelle, Rolf Stenberg
Venue: SIAM Journal on Numerical Analysis (1998)

We consider the design of finite element methods for the Naghdi shell model in the case when the deformation is bending dominated. Two formulations based on stabilizing techniques are introduced and it is proved that they are stable, hence free from locking. The theoretical estimates are confirmed by numerical benchmark studies.
Blockwise Perturbation Theory for Markov Chains
Authors: Xue Jungong, Gao Weiguo
Venue: SIAM Journal on Matrix Analysis and Applications (1999)

This paper is concerned with the relative sensitivity of the individual stationary probabilities of an irreducible Markov chain to small relative blockwise perturbations of the transition matrix. It is shown that this sensitivity depends on some quantities related to the stochastic complements of diagonal blocks of the transition matrix. For nearly uncoupled and nearly transient Markov chains, the stationary probabilities are sensitive to general perturbations in the relative sense. However, they are insensitive to small blockwise relative perturbations.
Erratum: A Uniqueness Result for the Linear System of Elasticity and Its Control Theoretical Consequences
Authors: Enrique Zuazua
Venue: SIAM Journal on Control and Optimization (1999)

In this note we explain why the three-dimensional counterexample of section 7.2 of the paper under consideration [E. Zuazua, SIAM J. Control Optim., 34 (1996), pp. 1473--1495] is incorrect. It concerns the existence of eigenfunctions for the Dirichlet Laplacian of a special form. We claimed the existence of particular three-dimensional domains in which these eigenfunctions do exist. However, in a recent joint work with G. Sweers [G. Sweers and E. Zuazua, J. Elasticity, to appear], we have proved that they may not exist in any bounded Lipschitz domain in dimensions $n\geq3.$
Space-efficient scheduling of nested parallelism
Authors: Girija J. Narlikar, Guy E. Blelloch
Venue: ACM Transactions on Programming Languages and Systems (TOPLAS) (1999)

Many of today's high-level parallel languages support dynamic, fine-grained parallelism. These languages allow the user to expose all the parallelism in the program, which is typically of a much higher degree than the number of processors. Hence an efficient scheduling algorithm is required to assign computations to processors at runtime. Besides having low overheads and good load balancing, it is important for the scheduling algorithm to minimize the space usage of the parallel program. This article presents an on-line scheduling algorithm that is provably space efficient and time efficient for nested-parallel languages. For a computation with depth D and serial space requirement S1, the algorithm generates a schedule that requires at most S1 + O(K&bull;D&bull;p) space (including scheduler space) on p processors. Here, K is a user-adjustable runtime parameter specifying the net amount of memory that a thread may allocate before it is preempted by the scheduler. Adjusting the value of K provides a trade-off between the running time and the memory requirement of a parallel computation. To allow the scheduler to scale with the number of processors we also parallelize the scheduler and analyze the space and time bounds of the computation to include scheduling costs. In addition to showing that the scheduling algorithm is space and time efficient in theory, we demonstrate that it is effective in practice. We have implemented a runtime system that uses our algorithm to schedule lightweight parallel threads. The results of executing parallel programs on this system show that our scheduling algorithm significantly reduces memory usage compared to previous techniques, without compromising performance.
Fast Evaluation of Radial Basis Functions: Moment-Based Methods
Authors: R. K. Beatson, G. N. Newsam
Venue: SIAM Journal on Scientific Computing (1998)

This paper presents a new method for the fast evaluation of univariate radial basis functions of the form $s(x) = \sum_{n=1}^N d_n \phi ( | x -x_n | ) $ to within accuracy $\epsilon$. The method can be viewed as a generalization of the fast multipole method in which calculations with far field expansions are replaced by calculations involving moments of the data. The method has the advantage of being adaptive to changes in $\phi$. That is, with this method changing to a new $\phi$ requires only coding a one- or two-line function for the (slow) evaluation of $\phi$. In contrast, adapting the usual fast multipole method to a new $\phi$ involves much mathematical analysis of appropriate series expansions and corresponding translation operators, followed by a substantial amount of work expressing this mathematics in code.
Fast texture synthesis using tree-structured vector quantization
Authors: Li-Yi Wei, Marc Levoy
Venue: Proceedings of the 27th annual conference on Computer graphics and interactive techniques (2000)

Texture synthesis is important for many applications in computer graphics, vision, and image processing. However, it remains difficult to design an algorithm that is both efficient and capable of generating high quality results. In this paper, we present an efficient algorithm for realistic texture synthesis. The algorithm is easy to use and requires only a sample texture as input. It generates textures with perceived quality equal to or better than those produced by previous techniques, but runs two orders of magnitude faster. This permits us to apply texture synthesis to problems where it has traditionally been considered impractical. In particular, we have applied it to constrained synthesis for image editing and temporal texture generation. Our algorithm is derived from Markov Random Field texture models and generates textures through a deterministic searching process. We accelerate this synthesis process using tree-structured vector quantization.
A model for designing adaptable software components
Authors: George T. Heineman
Venue: ACM SIGSOFT Software Engineering Notes (2000)

An important aim of software engineering is to produce reliable and robust software systems. As software systems grow in size, however, it becomes infeasible to design and construct software systems from scratch. Most software developers are familiar with reusing code from component libraries to speed up tedious programming tasks, such as constructing graphical user interfaces. However, it is still an elusive goal to construct applications entirely from pre-existing, independently developed components. We believe that such component-based development will only occur when application builders can adapt software components to suit their needs.The goal of this research is to develop novel techniques for designing software components that provide a mechanism for adapting their behavior. We aim to achieve higher levels of component use/reuse than existing approaches for reusing software components. The Active Interface technique we propose enables software components to provide two interfaces --- one for behavior and one for adapting that behavior as needed.We make a distinction between software evolution, where the component designer modifies the software component, and adaptation, where an application builder adapts the component for a different use. We also differentiate adaptation from customization; an end-user customizes a software component by choosing from a fixed set of options. An end-user adapts a software component by writing new code to alter existing functionality.
Early load address resolution via register tracking
Authors: Michael Bekerman, Adi Yoaz, Freddy Gabbay, Stephan Jourdan, Maxim Kalaev, Ronny Ronen
Venue: Proceedings of the 27th annual international symposium on Computer architecture (2000)

Higher microprocessor frequencies accentuate the performance cost of memory accesses. This is especially noticeable in the Intel's IA32 architecture where lack of registers results in increased number of memory accesses. This paper presents novel, non-speculative technique that partially hides the increasing load-to-use latency, by allowing the early issue of load instructions. Early load address resolution relies on register tracking to safely compute the addresses of memory references in the front-end part of the processor pipeline. Register tracking enables decode-time computation of register values by tracking simple operations of the form reg&plusmn;immediate. Register tracking may be performed in any pipeline stage following instruction decode and prior to execution. Several tracking schemes are proposed in this paper: Stack pointer tracking allows safe early resolution of stack references by keeping track of the value of the ESP register (the stack pointer). About 25% of all loads are stack loads and 95% of these loads may be resolved in the front-end. Absolute address tracking allows the early resolution of constant-address loads. Displacement-based tracking tackles all loads with addresses of the form reg&plusmn;immediate by tracking the values of all general-purpose registers. This class corresponds to 82% of all loads, and about 65% of these loads can be safely resolved in the front-end pipeline. The paper describes the tracking schemes, analyzes their performance potential in a deeply pipelined processor and discusses the integration of tracking with memory disambiguation.
Implementation and management of a mobile phone filtering system
Authors: Jyhi-Kong Wey, Pen-Kuan Huang, Hui-Chi Chang, Jiu-Yang Liu
Venue: International Journal of Network Management (2000)

This paper presents the system design and network management of a mobile phone filtering system &lpar;MOFIS&rpar; for filtering clones of cellular international calls by an IN-based service node approach. Copyright &copy; 2000 John Wiley Sons, Ltd.
On Wavewise Entropy Inequality for High Resolution Schemes II: Fully Discrete MUSCL Schemes with Exact Evolution in Small Time
Authors: Huanan Yang
Venue: SIAM Journal on Numerical Analysis (1998)

In this paper, we extend the framework and the convergence criteria of wavewise entropy inequality of [H. Yang, Math. Comp., 65 (1996), pp. 45--67] to fully discrete high resolution schemes satisfying certain TVD nonoscillatory conditions. For the Cauchy problem of convex conservation laws in one space dimension, we use one of the criteria to prove the convergence of the MUSCL scheme toward the entropy solution, assuming that each time step of the scheme consists of a minmod slope limiter, an exact time evolution, and a standard cell averaging; the CFL number is less than 0.5; and the initial condition is of bounded variation.
Initialization of Supervised Training for Parametric Estimation
Authors: P. Costa, P. Larzabal
Venue: Neural Processing Letters (1999)

This paper concerns the initialization problem of the training algorithm in Neural Networks. We focus herein on backpropagation networks with one hidden layer. The initialization of the weights is crucial; if the network is incorrectly initialized, it converges to local minima. The classical random initialization therefore appears as a very poor solution. If we were to consider the Taylor development of the mapping problem and the nonlinearity of sigmoids, the improvements could be very significant. We propose a new initialization scheme based on the search for an explicit approximate solution to the problem of mapping between pattern and target. Simulation results are presented which show that these original initializations avoid local minima, reduce training time, obtain a better generalization and estimate the network&lsquo;s size.
Corrected Operator Splitting for Nonlinear Parabolic Equations
Authors: Kenneth Hvistendahl Karlsen, Nils Henrik Risebro
Venue: SIAM Journal on Numerical Analysis (2000)

We present a corrected operator splitting (COS) method for solving nonlinear parabolic equations of a convection-diffusion type. The main feature of this method is the ability to correctly resolve nonlinear shock fronts for large time steps, as opposed to a standard operator splitting (OS) which fails to do so. COS is based on solving a conservation law for modeling convection, a heat-type equation for modeling diffusion and finally a certain ``residual'' conservation law for necessary correction. The residual equation represents the entropy loss generated in the hyperbolic (convection) step. In OS the entropy loss manifests itself in the form of too wide shock fronts. The purpose of the correction step in COS is to counterbalance the entropy loss so that correct width of nonlinear shock fronts is ensured. The polygonal method of Dafermos [ J. Math. Anal. Appl., 38 (1972), pp. 33--41] constitutes an important part of our solution strategy. It is shown that COS generates a compact sequence of approximate solutions which converges to the solution of the problem. Finally, some numerical examples are presented where we compare OS and COS methods with respect to accuracy.
Ambiguous Shape from Shading with Critical Points
Authors: Jean-Denis Durou, Didier Piau
Venue: Journal of Mathematical Imaging and Vision (2000)

The eikonal equation can have an infinite number of solutions when the image has critical points. We exhibit a family, indexed by a continuous parameter, of non isomorphic surfaces with one critical point, which give the same simple image. Hence, shape from shading can be an ill-posed problem when no additional condition on the shape is imposed, even when the image has critical points. Also, deformations without distortion are possible, i.e., there can exist a continuous deformation of the surface which does not modify its image.
Configuration Controllability of Simple Mechanical Control Systems
Authors: Andrew D. Lewis, Richard M. Murray
Venue: SIAM Review (1999)

In this paper we present a definition of ''configuration controllability'' for mechanical systems whose Lagrangian is kinetic energy with respect to a Riemannian metric minus potential energy. A computable test for this new version of controllability is derived. This condition involves an object that we call the symmetric product. Of particular interest is a definition of ''equilibrium controllability'' for which we are able to derive computable sufficient conditions. Examples illustrate the theory.
Providing integrated toolkit-level support for ambiguity in recognition-based interfaces
Authors: Jennifer Mankoff, Scott E. Hudson, Gregory D. Abowd
Venue: Proceedings of the SIGCHI conference on Human factors in computing systems (2000)

Interfaces based on recognition technologies are used extensively in both the commercial and research worlds. But recognizers are still error-prone, and this results in human performance problems, brittle dialogues, and other barriers to acceptance and utility of recognition systems. Interface techniques specialized to recognition systems can help reduce the burden of recognition errors, but building these interfaces depends on knowledge about the ambiguity inherent in recognition. We have extended a user interface toolkit in order to model and to provide structured support for ambiguity at the input event level. This makes it possible to build re-usable interface components for resolving ambiguity and dealing with recognition errors. These interfaces can help to reduce the negative effects of recognition errors. By providing these components at a toolkit level, we make it easier for application writers to provide good support for error handling. Further, with this robust support, we are able to explore new types of interfaces for resolving a more varied range of ambiguity.