ppxscal/embedding_network huggingface dataset:
GMRES On (Nearly) Singular Systems
Authors: Peter N. Brown, Homer F. Walker
Venue: SIAM Journal on Matrix Analysis and Applications (1997)

We consider the behavior of the GMRES method for solving a linear system $Ax = b$ when $A$ is singular or nearly so, i.e., ill conditioned. The (near) singularity of $A$ may or may not affect the performance of GMRES, depending on the nature of the system and the initial approximate solution. For singular $A$, we give conditions under which the GMRES iterates converge safely to a least-squares solution or to the pseudoinverse solution. These results also apply to any residual minimizing Krylov subspace method that is mathematically equivalent to GMRES. A practical procedure is outlined for efficiently and reliably detecting singularity or ill conditioning when it becomes a threat to the performance of GMRES.
Minimum area retiming with equivalent initial states
Authors: Naresh Maheshwari, Sachin S. Sapatnekar
Venue: Proceedings of the 1997 IEEE/ACM international conference on Computer-aided design (1997)

Traditional minimum area retiming algorithms attempt to achieve their prescribed objective with no regard to maintaining the initial state of the system. This issue is important for circuits such as controllers, and our work addresses this problem. The procedure described generates bounds on the retiming variables that guarantee an equivalent initial state after retiming. A number of possible sets of bounds can be derived, and each set is used to solve a minimum area retiming problem that is set up as a 0/1 mixed integer linear program, using a new technique that models the maximal sharing of flip-flops at latch outputs. The best solution is found through enumeration of these sets, terminated on achievement of a calculated lower bound. Experimental results show that after a small number of enumerations, optimal or near-optimal results are achievable.
File placement and process assignment due to resource sharing in a distributed system
Authors: Anna Hać
Venue: Proceedings of the 17th conference on Winter simulation (1985)

This paper presents a number of solutions to the problems of data access, concurrency control, transaction serialization, and deadlock control based on the examples of existing file systems. Also, policies for file placement and process assignment are discussed from the viewpoint of their impact on system performance and reliability. The impact of these policies depends on the solutions to the problems referred above. A simulation model of a file system is introduced. This model is validated using data collected in a small business installation. A number of simulation experiments are presented. It is shown how the decision about where to place a file or to assign a process can be based on the workload's and the system's characterization. An algorithm for improving performance and reliability by file placement and/or process assignment is finally presented.
A basic architecture supporting LGDG computation
Authors: Kechang Dai, Wolfgang K. Giloi
Venue: Proceedings of the 4th international conference on Supercomputing (1990)

In order to combine the benefits of dataflow and control-flow computation while avoiding the pitfalls of both, the authors propose a two-level model of large-grain dataflow computation, called LGDG computation. A formalism has been provided in a previous paper to prove the determinism of parallel program execution under this model. The current paper presents the basic LGDG computer architecture which is organized at two levels, called the graph level and the node level. The kernel of the node-level architecture is characterized by its non-branch RISC (N-RISC) feature, which ensures an optimal utilization of pipeline processing. This kernel is supported by various co-processors based on the principle of function migration. We will show in this paper how the graph-level architecture can be reduced to a matching unit, extended by a writable control store, through node migration and node aggregation. As a result, the matching overhead is drastically reduced, thus eliminating the most severe bottleneck of existing 'fine-grain' dataflow computers.
Testing object-oriented programs: making it simple
Authors: John Rosenberg, Michael Kölling
Venue: ACM SIGCSE Bulletin (1997)

One of the major difficulties facing anyone trying to teach the first programming course is how to encourage students to thoroughly test their programs. We would argue that the main reasons for this are the lack of suitable tools for testing and the need to write extra "debug" code in order to verify correct operation. We further argue that the problem is even worse with object-oriented languages because of multiple classes and encapsulation. In this paper we describe the testing tools within the Blue programming environment which allow object-oriented programs to be thoroughly tested without writing a single line of new code.
Similarity-based queries for time series data
Authors: Davood Rafiei, Alberto Mendelzon
Venue: Proceedings of the 1997 ACM SIGMOD international conference on Management of data (1997)

We study a set of linear transformations on the Fourier series representation of a sequence that can be used as the basis for similarity queries on time-series data. We show that our set of transformations is rich enough to formulate operations such as moving average and time warping. We present a query processing algorithm that uses the underlying R-tree index of a multidimensional data set to answer similarity queries efficiently. Our experiments show that the performance of this algorithm is competitive to that of processing ordinary (exact match) queries using the index, and much faster than sequential scanning. We relate our transformations to the general framework for similarity queries of Jagadish et al.
The PL Hierarchy Collapses
Authors: Mitsunori Ogihara
Venue: SIAM Journal on Computing (1998)

It is shown that the PL hierarchy PLH = PL ,\bigcup\limits\, PLPL ,\bigcup\limits\, PLPLPL ,\bigcup\limits\, \cdots$, defined in terms of the Ruzzo--Simon--Tompa relativization, collapses to PL.
Sparse Multifrontal Rank Revealing QR Factorization
Authors: Daniel J. Pierce, John G. Lewis
Venue: SIAM Journal on Matrix Analysis and Applications (1997)

We describe an algorithm to compute an approximate rank revealing sparse QR factorization. We use a two phase algorithm to provide especially high accuracy in the labeling of some columns as ``redundant,'' which ensures robustness in the use of our factorization in computing explicit bases of the nullspace.Our first phase is similar in outline to other proposed sparse RRQR factorizations, in that we couple a standard sparse QR factorization scheme with a condition estimator to develop a factorization with a well-conditioned leading block. There are important details in our implementation of the condition estimator and pivoting that enhance efficiency and reliability. However, the exceptional characteristic of our algorithm is its second phase, which ensures that columns labeled as redundant lead to highly accurate nullvectors. The second phase requires that we compute all columns of R explicitly in the first phase; we cannot discard ``redundant'' columns as is often done elsewhere. This condition, in the presence of pivoting to reveal the rank, requires dynamic data structures and necessarily degrades sparsity. But the additional work fits naturally into the multifrontal factorization's use of efficient dense vector kernels, minimizing overall cost.We present a theoretical analysis that shows that our use of approximate singular vectors does not degrade the quality of our rank-revealing factorization; we achieve an exponential bound like methods that use exact singular vectors. We provide results of numerical experiments and close with a discussion of limitations of this approach.
How to Make a Correct Multiprocess Program Execute Correctly on a Multiprocessor
Authors: Leslie Lamport
Venue: IEEE Transactions on Computers (1997)

A multiprocess program executing on a modern multiprocessor must issue explicit commands to synchronize memory accesses. A method is proposed for deriving the necessary commands from a correctness proof of the underlying algorithm in a formalism based on temporal relations among operation executions.
Automated design software for switched-capacitor IC's with symbolic simulator SCYMBAL
Authors: A. Konczykowska, M. Bon
Venue: Proceedings of the 25th ACM/IEEE Design Automation Conference (1988)

This paper presents SCYMBAL, a switched-capacitor symbolic simulator. The adopted algorithm, computer implementation, and program performances in comparison with other well-known realizations are discussed. Accompanying tools and the method of insertion in the integrated CAD system are presented. A new methodology of automated generation of circuit structures using symbolic simulator and concepts of artificial intelligence is presented and compared with algorithmic approach.
Dynamic HTML: the definitive reference
Authors: Danny Goodman
Venue:  (1998)

Dynamic HTML: The Definitive Reference is an indispensable compendium for Web content developers. It contains complete reference material for all of the HTML tags, CSS style attributes, browser document objects, and JavaScript objects supported by the various standards and the latest versions of Netscape Navigator and Microsoft Internet Explorer.
Tolerant synchronization for distributed simulations of interconnected computer networks
Authors: Peter Martini, Markus Rümekasten, Jens Tölle
Venue: Proceedings of the eleventh workshop on Parallel and distributed simulation (1997)

This paper presents the tolerant, hybrid synchronization schema and its benefits for the parallel and distributed simulation of interconnected computer networks. The hybrid schema combines conservative and optimistic synchronization approaches by using lookahead for scheduling special events and using the flexibility of Time Warp in certain cases. In addition to these classical approaches the introduction of the ¦tolerance¦ allows the distributed modules to simulate further ahead than guaranteed by the conservative synchronization schema. This results in significantly smaller simulation runtimes and many other benefits.
An optimal repartitioning decision policy
Authors: David M. Nicol, Paul F. Reynolds,  Jr.
Venue: Proceedings of the 17th conference on Winter simulation (1985)

The automated partitioning of simulations for parallel execution is a timely research problem. A simulation's run-time performance depends heavily on the nature of the inputs the simulation responds to. Consequently, a simulation's run-time behavior varies as a function of time. Since a simulation's run-time behavior is generally too complex to analytically predict, partitioning algorithms must be statistically based: they base their partitioning decisions on the simulation's observed behavior. Simulations which are partitioned statistically are vulnerable to radical changes in the run-time dynamics of the simulation. In this paper we discuss a dynamic repartitioning decision policy which detects change in a simulation's run-time behavior and reacts to this change. This decision policy optimally balances the costs and potential benefits of repartitioning a running simulation.
Close-Form Solution and Parameter Selection for Convex Minimization-Based Edge-Preserving Smoothing
Authors: Stan Z. Li
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1998)

This work presents a new approach for the analysis of convex minimization-based edge-preserving image smoothing and the parameter selection therein. The global solution, that is, the response of a convex smoothing model to the ideal step edge, is derived in close-form. By analyzing the close-form solution, insights are drawn into how the optimal solution responds to edges in the data and how the parameter values affect resultant edges in the solution. Based on this, a scheme is proposed for selecting parameters to achieve desirable responses at edges. The theoretic results are substantiated by experiments.
The architecture of a highly integrated simulation system
Authors: Michel Heydemann, Alain Plaignaud, Daniel Dure
Venue: Proceedings of the 25th ACM/IEEE Design Automation Conference (1988)

A mechanism for integrating simulators into CAD systems has been implemented in order to provide high-performance interaction during the course of a design. This mechanism replaces slow text-based interfaces by a persistent programming technique where the database is viewed as an extension of dynamically allocated memory. Organization of simulation data and implementation of the interface mechanism are described.
EVA: A Flexible Programming Method for Evolving Systems
Authors: Saeko Matsuura, Hironobu Kuruma, Shinichi Honiden
Venue: IEEE Transactions on Software Engineering (1997)

Our goal is to establish a flexible programming support for evolving systems that will enable us to modify programs using less labor, while maintaining good quality during service life. EVA (EVolution mechanism for flexible Agent) was developed to allow a flexible programming support system to be constructed based on our programming method for evolving systems. We consider that programming methods for evolving systems need to satisfy the following essential conditions. First, they need to make it easy to specify changes in a system in terms of new requirements. Second, they need to have a procedure for transmitting the new requirements to a program. Third, they need to be able to guarantee that the resultant program will meet the new requirements. Finally, because of the repetitive nature of much evolving systems work, they need to provide for the reuse of similar modifications during programming.In order to overcome limitations in program modification techniques which have only considered programming products, programming processes have been introduced into our method. To achieve our goal, we have formulated programming products and programming processes using such formal techniques as functional programming, type theory, modules, parameterized programming and natural deduction, and have constructed a mechanism of reusing these formal programming processes. This paper explains a case study which shows how to develop an evolving system using EVA and it discusses how we can use EVA's mechanism effectively.
Property testing and its connection to learning and approximation
Authors: Oded Goldreich, Shari Goldwasser, Dana Ron
Venue: Journal of the ACM (JACM) (1998)

In this paper, we consider the question of determining whether a function f has property P or is &egr;-far from any function with property P. A property testing algorithm is given a sample of the value of f on instances drawn according to some distribution. In some cases, it is also allowed to query f on instances of its choice. We study this question for different properties and establish some connections to problems in learning theory and approximation.In particular, we focus our attention on testing graph properties. Given access to a graph G in the form of being able to query whether an edge exists or not between a pair of vertices, we devise algorithms to test whether the underlying graph has properties such as being bipartite, k-Colorable, or having a p-Clique (clique of density p with respect to the vertex set). Our graph property testing algorithms are probabilistic and make assertions that are correct with high probability, while making a number of queries that is independent of the size of the graph. Moreover, the property testing algorithms can be used to efficiently (i.e., in time linear in the number of vertices) construct partitions of the graph that correspond to the property being tested, if it holds for the input graph.
An Optimal Probabilistic Protocol for Synchronous Byzantine Agreement
Authors: Pesech Feldman, Silvio Micali
Venue: SIAM Journal on Computing (1997)

Broadcasting guarantees the recipient of a message that everyone else has received the same message. This guarantee no longer exists in a setting in which all communication is person-to-person and some of the people involved are untrustworthy: though he may claim to send the same message to everyone, an untrustworthy sender may send different messages to different people. In such a setting, Byzantine agreement offers the "best alternative" to broadcasting. Thus far, however, reaching Byzantine agreement has required either many rounds of communication (i.e., messages had to be sent back and forth a number of times that grew with the size of the network) or the help of some external trusted party.In this paper, for the standard communication model of synchronous networks in which each pair of processors is connected by a private communication line, we exhibit a protocol that, in probabilistic polynomial time and without relying on any external trusted party, reaches Byzantine agreement in an expected constant number of rounds and in the worst natural fault model. In fact, our protocol successfully tolerates that up to 1/3 of the processors in the network may deviate from their prescribed instructions in an arbitrary way, cooperate with each other, and perform arbitrarily long computations.Our protocol effectively demonstrates the power of randomization and zero-knowledge computation against errors. Indeed, it proves that "privacy" (a fundamental ingredient of one of our primitives), even when is not a desired goal in itself (as for the Byzantine agreement problem), can be a crucial tool for achieving correctness.Our protocol also introduces three new primitives---graded broadcast, graded verifiable secret sharing, and oblivious common coin---that are of independent interest, and may be effectively used in more practical protocols than ours.
Object Recognition Robust Under Translations, Deformations, and Changes in Background
Authors: Rolf P. Würtz
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1997)

Recognition systems based on model matching using low level features often fail due to a variation in background. As a solution, I present a system for the recognition of human faces independent of hairstyle. Correspondence maps between an image and a model are established by coarse-fine matching in a Gabor pyramid. These are used for hierarchical recognition.
Implementation and Analysis of Path History in Dynamic Branch Prediction Schemes
Authors: Shlomo Reches, Shlomo Weiss
Venue: IEEE Transactions on Computers (1998)

Accurate branch prediction is essential for providing higher performance levels in modern processors. Many branch predictors use branch execution history to identify repetitive branch behavior. Path history provides additional information that may help separate sequences of different branch instructions with identical execution history. We present a method to implement path history in hardware-based branch prediction, and a comprehensive simulation study of branch prediction strategies that integrate path history.
Language based state saving extensions for optimistic parallel simulation
Authors: Fabian Gomes, Brian Unger, John Cleary
Venue: Proceedings of the 28th conference on Winter simulation (1996)

One of the greatest challenges in making optimistic synchronization techniques such as Time Warp practical tools is making state saving efficient and easy to use. State saving is necessary so that when optimistic execution is found to be out of order, rollback can be used to recover an earlier execution state. Previous work has shown that the most robust and efficient technique for saving state is to incrementally save copies of small parts of the state at the point that they are modified. Unfortunately, this requires sig nificant programmer intervention to insert additional code. In this paper, C++ language extensions for trans parent incremental state saving are presented. Operator overloading and type parameterization are used to incrementally save basic data types. Building on this, two new type-specifiers, "recover" and "nourecover" are described. They allow a single declaration to specify, for example, that all the member variables of a class are to be state saved, and for all the resulting state saving calls to be automatically generated. Issues, including how these specifiers interact with class inheritance and function declarations are examined and solved.
A survey on bit dimension optimization strategies of microprograms
Authors: Sunil R. Das, Amiya R. Nayak
Venue: Proceedings of the 23rd annual workshop and symposium on Microprogramming and microarchitecture (1990)

Microprogram optimization is one way to increase efficiency, and optimization can be crucial in some applications. Optimization refers to a reduction of execution time of microprograms, or of the control store size, B &times; W, where W represents the word dimension of the control store which is the number of words of control store required for certain application, and B represents the bit dimension which is the number of bits per word of control store. The various optimization strategies can be broadly classified under four categories : bit dimension reduction, word dimension reduction, state reduction, and heuristic reduction. A survey of the various bit dimension optimization techniques has been presented by Agerwala in his 1976 paper, where the techniques are critically analyzed and compared, and the results of analysis are discussed. This paper further augments the work of Agerwala, taking into account the optimization methods developed later and hence not discussed by him. Also, the present study considers the optimization problem in the case of polyphase microinstructions in addition to that for monophase microinstructions. The prospective, current status, and future trends in this direction are also briefly outlined.
Stereo and Specular Reflection
Authors: Dinkar N. Bhat, Shree K. Nayar
Venue: International Journal of Computer Vision (1998)

The problem of accurate depth estimation using stereo in the presence of specular reflection is addressed. Specular reflection, a fundamental and ubiquitous reflection mechanism, is viewpoint dependent and can cause large intensity differences at corresponding points, resulting in significant depth errors. We analyze the physics of specular reflection and the geometry of stereopsis which lead to a relationship between stereo vergence, surface roughness, and the likelihood of a correct match. Given a lower bound on surface roughness, an optimal binocular stereo configuration can be determined which maximizes precision in depth estimation despite specular reflection. However, surface roughness is difficult to estimate in unstructured environments. Therefore, trinocular configurations, independent of surface roughness are determined such that at each scene point visible to all sensors, at least one stereo pair can produce correct depth. We have developed a simple algorithm to reconstruct depth from the multiple stereo pairs.
A Domain Decomposition Method for the Acoustic Wave Equation with Discontinuous Coefficients and Grid Change
Authors: Alain Bamberger, Roland Glowinski, Quang Huy Tran
Venue: SIAM Journal on Numerical Analysis (1997)

A domain decomposition technique is proposed for the computation of the acoustic wave equation in which the bulk modulus and density fields are allowed to be discontinuous at the interfaces. Inside each subdomain, the method presented coincides with the second-order finite difference schemes traditionally used in geophysical modeling. However, the possibility of assigning to each subdomain its own space-step makes numerical simulations much less expensive.Another interest of the method lies in the fact that its hybrid variational formulation naturally leads to exact equations for gridpoints on the interfaces. Transposing Babuska--Brezzi's formalism on mixed and hybrid finite elements provides a suitable functional framework for this domain decomposition formulation and shows that the inf-sup condition remains the basic requirement for convergence to occur.