ppxscal/embedding_network huggingface dataset:
Partitioned garbage collection of a large object store
Authors: Umesh Maheshwari, Barbara Liskov
Venue: Proceedings of the 1997 ACM SIGMOD international conference on Management of data (1997)

We present new techniques for efficient garbage collection in a large persistent object store. The store is divided into partitions that are collected independently using information about inter-partition references. This information is maintained on disk so that it can be recovered after a crash. We use new techniques to organize and update this information while avoiding disk accesses. We also present a new global marking scheme to collect cyclic garbage across partitions. Global marking is piggybacked on partitioned collection; the result is an efficient scheme that preserves the localized nature of partitioned collection, yet is able to collect all garbage. We have implemented the part of garbage collection responsible for maintaining information about inter-partition references. We present a performance study to evaluate this work; the results show that our techniques result in substantial savings in the usage of disk and memory.
The Cost of Derandomization: Computability or Competitiveness
Authors: Xiaotie Deng, Sanjeev Mahajan
Venue: SIAM Journal on Computing (1997)

Recently, much work has been done in game theory towards understanding the bounded rationality of players in infinite games. This requires the strategies of realistic players to be restricted to have bounded resources of reasoning. (See [H. Simon, Decision and Organization, North--Holland, Amsterdam, 1972, pp. 161--176] for an extensive discussion; also see [X. Deng and C. H. Papadimitriou, Math. Oper. Res., 19 (1994), pp. 257--266], [C. Futia, J. Math. Econom., 4 (1977), pp. 289--299], [V. Knoblauch, Games Econom. Behav., 7 (1994), pp. 381--389], [E. Kalai and W. Stanford, Econometria, 56 (1988), pp. 397--410], [A. Neyman, Econom. Lett., 19 (1985), pp. 227--229], and [C. H. Papadimitriou, Game Theory Econom. Behav., 4 (1992), pp. 122--131].) In this paper, we discuss infinite two-person games, focusing on the case where our player follows a computable strategy and the adversary may use any strategy, which formulates the notion of computer against extremely formidable nature. In this context, we say that an infinite game is semicomputably determinate if either the adversary has a winning strategy or our player has a computable winning strategy.We show that, whereas all open games are semicomputably determinate, there is a semicomputably indeterminate closed game. Since we want to prove an indeterminacy result for closed games and since the adversary's strategy set is uncountable and our player's strategy set is countable, our proof for the indeterminacy result requires a new diagonalization technique, which might be useful in other similar cases. Our study of semicomputable games was inspired by online computing problems. In this direction, we discuss several possible applications to derandomization in online computing, with the restriction that the strategies of our player should be computable.We also study the power of randomization for the classical case where our player is allowed to play according to unrestricted strategies. An indeterminate game is obtained for which both players have a simple randomized winning strategy against all of the deterministic strategies of the opponent.
VP: a new operation for semaphores
Authors: K. C. Tai, Richard H. Carver
Venue: ACM SIGOPS Operating Systems Review (1996)

A semaphore is a non-negative integer variable on which only operations P and V are allowed. The semaphore construct (with various extensions) is supported by many operating systems and is often used to implement other synchronization constructs. Since the semaphore construct is low-level, a semaphore-based program may contain synchronization errors that are very difficult to detect. In this paper, we propose a new operation VP (s1,s2), where s1 and s2 are distinct or identical semaphores. An execution of VP(s1,s2) by a process T is equivalent to that of "V (s1); P(s2)" except that when T starts the V (s1) operation, T is guaranteed to be the next process to access s2 (i.e., T will execute the P(s2) operation before another process executes a P(s2) or V(s2) operation.) Section 2 shows several examples to illustrate the advantages of the VP operation. Section 3 concludes this paper. In this paper, we assume that the queue for a semaphore is first-in-first-out and that the order of processes blocked in a semaphore queue is the same order in which they executed P operations on the semaphore. We also assume that the scheduling of processes in a concurrent program is fair, i.e., each process ready for execution will eventually be selected as the running process. Programs in this paper use Ada-like syntax.
Application-driven synthesis of core-based systems
Authors: Darko Kirovski, Chunho Lee, Miodrag Potkonjak, William Mangione-Smith
Venue: Proceedings of the 1997 IEEE/ACM international conference on Computer-aided design (1997)

We developed a new hierarchical modular approach for synthesis of area-minimal core-based data-intensive systems. The optimization approach employs a novel global least-constraining most-constrained heuristic to minimize the instruction cache misses for a given application, instruction cache size and organization. Based on this performance optimization technique, we constructed a strategy to search for a minimal-area processor core, and an instruction and data cache which satisfy the performance characteristics of a set of target applications. The synthesis platform integrates the existing modeling, profiling, and simulation tools with the developed system-level synthesis tools. The effectiveness of the approach is demonstrated on a variety of modern real-life multimedia and communication applications.
Independent verification and validation: a missing link in simulation methodology?
Authors: James D. Arthur, Richard E. Nance
Venue: Proceedings of the 28th conference on Winter simulation (1996)

Independent verification and validation (IV&V) is a powerful tool that can be used to mitigate the increasing complexities associated with an ever-expanding set of modeling and simulation problems. In this paper we discuss the use of independent V&V within the modeling and simulation community. Literature reviews and conversations with experienced technical managers serve as a basis for our conjecture that (a) validation is the major focus of most modeling and simulation efforts, (b) verification plays only a secondary role, and (c) independent V&V is, for all practical purposes, being ignored. In an effort to raise the awareness of the benefits and applicability of independent V&V within the modeling and simulation community, we describe in a step-by-step fashion the application of independent V&V to one particular life cycle model of a simulation study.
Anisotropic Textures with Arbitrary Orientation
Authors: Murilo P. Almeida
Venue: Journal of Mathematical Imaging and Vision (1997)

We present a Markov random field (MRF) model for digital images capable of representing anisotropic textures with arbitrary orientations. The discrete Hamiltonian is obtained through finite difference discretization of a continuous elliptic operator on R &sup2;, together with a polynomial perturbation.We present the solution of a non-linear system of algebraic equations that estimates the orientation angle and the elliptic operator parameters in terms of the estimated discrete Hamiltonian parameters.We perform experiments of simulation and retrieval of parameters using, respectively, the Gibbs sampler algorithm and the variational estimators for MRF. We use also the estimation algorithm to identify relative rotation of digital images of the same realistic picture scanned at various different orientations.
Uniformly Accurate Schemes for Hyperbolic Systems with Relaxation
Authors: Russel E. Caflisch, Shi Jin, Giovanni Russo
Venue: SIAM Journal on Numerical Analysis (1997)

We develop high-resolution shock-capturing numerical schemes for hyperbolic systems with relaxation. In such systems the relaxation time may vary from order-1 to much less than unity. When the relaxation time is small, the relaxation term becomes very strong and highly stiff, and underresolved numerical schemes may produce spurious results. Usually one cannot decouple the problem into separate regimes and handle different regimes with different methods. Thus it is important to have a scheme that works uniformly with respect to the relaxation time. Using the Broadwell model of the nonlinear Boltzmann equation we develop a second-order scheme that works effectively, with a fixed spatial and temporal discretization, for all ranges of the mean free path. Formal uniform consistency proof for a first-order scheme and numerical convergence proof for the second-order scheme are also presented. We also make numerical comparisons of the new scheme with some other schemes. This study is motivated by the reentry problem in hypersonic computations.
An Analytical Method for Predicting the Performance of Parallel Image Processing Operations
Authors: Zoltan Johasz
Venue: The Journal of Supercomputing (1998)

This paper presents an analytical performance prediction model and methodology that can be used to predict the execution time, speedup, scalability and similar performance metrics of a large set of image processing operations running on a p-processor parallel system. The model which requires only a few parameters obtainable on a minimal system can help in the systematic design, evaluation and performance tuning of parallel image processing systems. Using the model one can reason about the performance of a parallel image processing system prior to implementation. The method can also support programmers in detecting critical parts of an implementation and system designers in predicting hardware performance and the effect of hardware parameter changes on performance. The execution of parallel image processing operations was studied and operations were arranged in three main problem classes based on data locality and the communication patterns of the algorithms. The core of the method is the derivation of the overhead function, as it is the overhead that determines the achievable speedup. The overheads were examined and modelled for each class. The use of the method is illustrated by four class-representative image processing algorithms: image-scalar addition, convolution, histogram calculation and the Fast Fourier Transform. The developed performance model has been validated on a 16-node parallel machine and it has been shown that the model is able to predict the parallel run-time and other performance metrics of parallel image processing operations accurately.
Synthesis and floorplanning for large hierarchical FPGAs
Authors: H. Krupnova, C. Rabedaoro, G. Saucier
Venue: Proceedings of the 1997 ACM fifth international symposium on Field-programmable gate arrays (1997)

Because the VLSI circuits complexity growth, the trend in design is towards divide-and-conquer schemes, in which circuits are composed of blocks, standard macros or custom macros. From the other side, to allow an implementation of large digital circuits, increased capacity target FPGAs are organized hierarchically. In this paper, we present a hierarchical FPGA floorplanning method which takes into account both the hierarchy of the design and the hierarchy of the target. The method aims at minimization the timing and balancing cost of the floorplan and is based on automatic detection of macro blocks and assigning them to the target FPGA hierarchical zones.
Efficient Solution of Linearly Coupled Lyapunov Equations
Authors: Emmanuel G. Collins,  Jr., A. Scottedward Hodel
Venue: SIAM Journal on Matrix Analysis and Applications (1997)

A numerical procedure is presented for the efficient solution of sets of linearly coupled matrix Lyapunov equations. Such equations arise in numerical continuation methods for the design of robust and/or low-order control systems.
Introduction to simulation in health care
Authors: Julie C. Lowery
Venue: Proceedings of the 28th conference on Winter simulation (1996)

The purpose of this article is to discuss some of the more challenging issues associated with conducting simulation in healthcare., The current healthcare environment is ripe for the use of simulation. The pressure to control costs is higher than ever, so, there is a critical need for powerful tools which can help clinicians and administrators (our clients) make good decisions on how to achieve objectives of reducing costs while maintaining high quality care. In addition, the highly stochastic nature of disease processes, as well as the complexity of subsystem interactions, makes simulation the decision-support tool of choice for analyzing the organization and delivery of healthcare services. However, for simulation to reach its potential as a major weapon in the fight against spiraling healthcare costs, pragmatic approaches to several challenging technical questions must be offered and discussed. Therefore, this article will present approaches to dealing with the following, frequently encountered tactical issues in simulating healthcare services--degree of model complexity, definitions of input distributions, model validation, and interpretation of findings. The last issue to be discussed is less of a technical concern, and instead addresses the promotion of simulation in healthcare.
Variance property of discontinuous perturbation analysis
Authors: Leyuan Shi
Venue: Proceedings of the 28th conference on Winter simulation (1996)

In recent article we presented a Discontinuous Perturbation Analysis (DPA) to deal with discontinuous sample performance functions. DPA is applicable to derivative estimation with respect to most threshold type of problems in Discrete Event Dynamic Systems (DEDS). In this paper, we examine the variance property of DPA method through a few examples. We will demonstrate that a better variance reduction can be obtained via DPA approach even if IPA Infinitesimal Perturbation Analysis (IPA) is applicable. A numerical example is also provided to compare DPA with other derivative estimation techniques.
Can program profiling support value prediction?
Authors: Freddy Gabbay, Avi Mendelson
Venue: Proceedings of the 30th annual ACM/IEEE international symposium on Microarchitecture (1997)

This paper explores the possibility of using program profiling to enhance the efficiency of value prediction. Value prediction attempts to eliminate true-data dependencies by predicting the outcome values of instructions at run-time and executing true-data dependent instructions based on that prediction. So far, all published papers in this area have examined hardware-only value prediction mechanisms. In order to enhance the efficiency of value prediction, it is proposed to employ program profiling to collect information that describes the tendency of instructions in a program to be value-predictable. The compiler that acts as a mediator can pass this information to the value-prediction hardware mechanisms. Such information can be exploited by the hardware in order to reduce mispredictions, better utilize the prediction table resources, distinguish between different value predictability patterns and still benefit from the advantages of value prediction to increase instruction-level parallelism. We show that our new method outperforms the hardware-only mechanisms in most of the examined benchmarks.
Fuzzy Logic for Biological and Agricultural Systems
Authors: Brian Center, Brahm P. Verma
Venue: Artificial Intelligence Review (1998)

Fuzzy logic is a powerful concept for handling non-linear, time-varying, adaptive systems. It permits the use of linguistic values of variables and imprecise relationships for modeling system behavior. The paper presents an overview of fuzzy logic modeling techniques, its applications to biological and agricultural systems and an example showing the steps of constructing a fuzzy logic model.
Parallel Preconditioning with Sparse Approximate Inverses
Authors: Marcus J. Grote, Thomas Huckle
Venue: SIAM Journal on Scientific Computing (1997)

A parallel preconditioner is presented for the solution of general sparse linear systems of equations. A sparse approximate inverse is computed explicitly and then applied as a preconditioner to an iterative method. The computation of the preconditioner is inherently parallel, and its application only requires a matrix-vector product. The sparsity pattern of the approximate inverse is not imposed a priori but captured automatically. This keeps the amount of work and the number of nonzero entries in the preconditioner to a minimum. Rigorous bounds on the clustering of the eigenvalues and the singular values are derived for the preconditioned system, and the proximity of the approximate to the true inverse is estimated. An extensive set of test problems from scientific and industrial applications provides convincing evidence of the effectiveness of this approach.
Quadratic placement revisited
Authors: C. J. Alpert, T. Chan, D. J.-H. Huang, I. Markov, K. Yan
Venue: Proceedings of the 34th annual Design Automation Conference (1997)

The "quadratic placement" methodology is rooted in [Module Placement Based on Resistive Network Optimization, Proud: A Sea-Of-Gate Placement Algorithm, A Combined Force and Cut Algorithm for Hierarchical VLSI Layout]and is reputedly used in many commercial and in-house tools forplacement of standard-cell and gate-array designs. The methodologyiterates between two basic steps: solving sparse systems oflinear equations, and repartitioning. This work dissects the implementationand motivations for quadratic placement. We firstshow that (i) Krylov subspace engines for solving sparse systemsof linear equations are more effective than the traditional successiveover-relaxation (SOR) engine [A Unified Approach to Partitioning and Placement] and (ii) order convergence criteriacan maintain solution quality while using substantially fewersolver iterations. We then discuss the motivations and relevanceof the quadratic placement approach, in the context of past and futurealgorithmic technology, performance requirements, and designmethodology. We provide evidence that the use of numerical linearsystems solvers with quadratic wirelength objective may be due tothe pre-1990's weakness of min-cut partitioners, i.e., numerical engineswere needed to provide helpful hints to min-cut partitioners.Finally, we note emerging methodology drivers in deep-submicrondesign that may require new placement approaches to the placement problem.
Trace-based mobile network emulation
Authors: Brian D. Noble, M. Satyanarayanan, Giao T. Nguyen, Randy H. Katz
Venue: ACM SIGCOMM Computer Communication Review (1997)

Subjecting a mobile computing system to wireless network conditions that are realistic yet reproducible is a challenging problem. In this paper, we describe a technique called trace modulation that re-creates the observed end-to-end characteristics of a real wireless network in a controlled and repeatable manner. Trace modulation is transparent to applications and accounts for all network traffic sent or received by the system under test. We present results that show that it is indeed capable of reproducing wireless network performance faithfully.
Optimal Control for Holonomic and Nonholonomic Mechanical Systems with Symmetry and Lagrangian Reduction
Authors: Wang-Sang Koon, Jerrold E. Marsden
Venue: SIAM Journal on Control and Optimization (1997)

In this paper we establish necessary conditions for optimal control using the ideas of Lagrangian reduction in the sense of reduction under a symmetry group. The techniques developed here are designed for Lagrangian mechanical control systems with symmetry. The benefit of such an approach is that it makes use of the special structure of the system, especially its symmetry structure, and thus it leads rather directly to the desired conclusions for such systems.Lagrangian reduction can do in one step what one can alternatively do by applying the Pontryagin maximum principle followed by an application of Poisson reduction. The idea of using Lagrangian reduction in the sense of symmetry reduction was also obtained by Bloch and Crouch [Proc. 33rd CDC, IEEE, 1994, pp. 2584--2590] in a somewhat different context, and the general idea is closely related to those in Montgomery [Comm. Math. Phys., 128 (1990), pp. 565--592] and Vershik and Gershkovich [Dynamical Systems VII, V. Arnold and S. P. Novikov, eds., Springer-Verlag, 1994]. Here we develop this idea further and apply it to some known examples, such as optimal control on Lie groups and principal bundles (such as the ball and plate problem) and reorientation examples with zero angular momentum (such as the satellite with moveable masses). However, one of our main goals is to extend the method to the case of nonholonomic systems with a nontrivial momentum equation in the context of the work of Bloch, Krishnaprasad, Marsden, and Murray [Arch. Rational Mech. Anal., (1996), to appear]. The snakeboard is used to illustrate the method.
JSpace: implementation of a Linda system in Java
Authors: Parcal Ledru
Venue: ACM SIGPLAN Notices (1998)

This paper describes an implementation of Linda for Java. Several capabilities of Java such as rich typing and object oriented programming are used to provide a powerful model. The implementation provides the functionality of Linda as well as some extensions taking advantages of Java. A short presentation of the Linda model and some examples are also provided.
Analysis of Moving Mesh Partial Differential Equations with Spatial Smoothing
Authors: Weizhang Huang, Robert D. Russell
Venue: SIAM Journal on Numerical Analysis (1997)

Two moving mesh partial differential equations (MMPDEs) with spatial smoothing are derived based upon the equidistribution principle. This smoothing technique is motivated by the robust moving mesh method of Dorfi and Drury [J. Comput. Phys., 69 (1987), pp. 175--195]. It is shown that under weak conditions the basic property of no node-crossing is preserved by the spatial smoothing, and a local quasi-uniformity property of the coordinate transformations determined by these MMPDEs is proven. It is also shown that, discretizing the MMPDEs using centered finite differences, these basic properties are preserved.