ppxscal/embedding_network huggingface dataset:
Better Bounds for Online Scheduling
Authors: Susanne Albers
Venue: SIAM Journal on Computing (1999)

We study a classical problem in online scheduling. A sequence of jobs must be scheduled on m identical parallel machines. As each job arrives, its processing time is known. The goal is to minimize the makespan. Bartal et al. [ J. Comput. System Sci., 51 (1995), pp. 359--366] gave a deterministic online algorithm that is 1.986-competitive. Karger, Phillips, and Torng [ J. Algorithms, 20 (1996), pp. 400--430] generalized the algorithm and proved an upper bound of 1.945. The best lower bound currently known on the competitive ratio that can be achieved by deterministic online algorithms is equal to 1.837. In this paper we present an improved deterministic online scheduling algorithm that is 1.923-competitive; for all $m\geq 2$. The algorithm is based on a new scheduling strategy, i.e., it is not a generalization of the approach by Bartal et al. Also, the algorithm has a simple structure. Furthermore, we develop a better lower bound. We prove that, for general m, no deterministic online scheduling algorithm can be better than 1.852-competitive.
An Omnifont Open-Vocabulary OCR System for English and Arabic
Authors: Issam Bazzi, Richard Schwartz, John Makhoul
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1999)

We present an omnifont, unlimited-vocabulary OCR system for English and Arabic. The system is based on Hidden Markov Models (HMM), an approach that has proven to be very successful in the area of automatic speech recognition. In this paper we focus on two aspects of the OCR system. First, we address the issue of how to perform OCR on omnifont and multi-style data, such as plain and italic, without the need to have a separate model for each style. The amount of training data from each style, which is used to train a single model, becomes an important issue in the face of the conditional independence assumption inherent in the use of HMMs. We demonstrate mathematically and empirically how to allocate training data among the different styles to alleviate this problem. Second, we show how to use a word-based HMM system to perform character recognition with unlimited vocabulary. The method includes the use of a trigram language model on character sequences. Using all these techniques, we have achieved character error rates of 1.1 percent on data from the University of Washington English Document Image Database and 3.3 percent on data from the DARPA Arabic OCR Corpus.
Perspectives on Analytical Modeling of Small Geometry MOSFETs in SPICE for Low Voltage/Low Power CMOS Circuit Design
Authors: Daniel Foty
Venue: Analog Integrated Circuits and Signal Processing (1999)

The present &ldquo;state of the art&rdquo; in analytical MOSFET modeling for SPICE circuit simulation is reviewed, with emphasis on the circuit design usage of these models. It is noted that the model formulation represents an &ldquo;upper limit&rdquo; of what is possible from any type of model, but that good parameter extraction is required to most closely approach that limit. The individual model types presently in common use are examined, with discussion of the behavior of each model, its strengths and weaknesses, its applicability to certain types of circuits, and criteria that a circuit design &ldquo;consumer&rdquo; can employ to judge a model before using it for circuit design. Some related issues, such as node charge and gate capacitance modeling, charge conservation, and statistical simulation of process variations, are also evaluated. Finally, new trends, directions, and requirements of MOSFET modeling for circuit simulation are considered.
A response to the commentaries on CoRR
Authors: Joseph Y. Halpern
Venue: ACM Journal of Computer Documentation (JCD) (2000)

This paper responds to specific comments on, suggestions about, and analysis of ACMs Computing Research Repository (CoRR), agruing that CoRR is both viable and suitably placed amid current online publishing alternatives.
Multi-dimensional selectivity estimation using compressed histogram information
Authors: Ju-Hong Lee, Deok-Hwan Kim, Chin-Wan Chung
Venue: ACM SIGMOD Record (1999)

The database query optimizer requires the estimation of the query selectivity to find the most efficient access plan. For queries referencing multiple attributes from the same relation, we need a multi-dimensional selectivity estimation technique when the attributes are dependent each other because the selectivity is determined by the joint data distribution of the attributes. Additionally, for multimedia databases, there are intrinsic requirements for the multi-dimensional selectivity estimation because feature vectors are stored in multi-dimensional indexing trees. In the 1-dimensional case, a histogram is practically the most preferable. In the multi-dimensional case, however, a histogram is not adequate because of high storage overhead and high error rates. In this paper, we propose a novel approach for the multi-dimensional selectivity estimation. Compressed information from a large number of small-sized histogram buckets is maintained using the discrete cosine transform. This enables low error rates and low storage overheads even in high dimensions. In addition, this approach has the advantage of supporting dynamic data updates by eliminating the overhead for periodical reconstructions of the compressed information. Extensive experimental results show advantages of the proposed approach.
Conditioning of Pseudospectral Matrices for Certain Domain Decompositions
Authors: Andreas Karageorghis, Marcin Paprzycki
Venue: Journal of Scientific Computing (1999)

In this paper we examine the conditioning of the matrices resulting from certain conforming pseudospectral approximations. In particular, we consider non-conforming domain decompositions in rectangular domains and the solution of fourth order problems. We investigate the way in which the poor conditioning of these matrices affects the performance, in terms of accuracy, of various direct methods of solution of the resulting systems. We also show how a simple iterative refinement procedure can improve the accuracy of the results obtained with a capacitance technique.
Green's Functions for Multiply Connected Domains via Conformal Mapping
Authors: Mark Embree, Lloyd N. Trefethen
Venue: SIAM Review (1999)

A method is described for the computation of the Green's function in the complex plane corresponding to a set of K symmetrically placed polygons along the real axis. An important special case is a set of K real intervals. The method is based on a Schwarz-Christoffel conformal map of the part of the upper half-plane exterior to the problem domain onto a semi-infinite strip whose end contains K-1 slits. From the Green's function one can obtain a great deal of information about polynomial approximations, with applications in digital filters and matrix iterations. By making the end of the strip jagged, the method can be generalized to weighted Green's functions and weighted approximations.
Simulating Project Work Processes and Organizations: Toward a Micro-Contingency Theory of Organizational Design
Authors: Raymond E. Levitt, Jan Thomsen, Tore R. Christiansen, John C. Kunz, Yan Jin, Clifford Nass
Venue: Management Science (1999)

The Virtual Design Team (VDT) extends and operationalizes Galbraith's (1973) information-processing view of organizations. VDT simulates the micro-level information processing, communication, and coordination behavior of participants in a project organization and predicts several measures of participant and project-level performance. VDT-1 (Cohen 1991) and VDT-2 (Christiansen 1993) modeled project organizations containing actors with perfectly congruent goals engaged in complex but routine engineering design work within static organization structures. VDT-3 extends the VDT-2 work process representation to include measures of activity flexibility, complexity, uncertainty, and interdependence strength. It explicitly models the effects of goal incongruency between agents on their information processing and communication behavior while executing more flexible tasks. These extensions allow VDT to model more flexible organizations executing less routine work processes. VDT thus bridges rigorously between cognitive and social psychological microorganization theory and sociological and economic macro-organization theory for project teams. VDT-3 has been used to model and simulate the design of two major subsystems of a complex satellite launch vehicle. This case study provides initial evidence that the microcontingency theory embodied in VDT-3 can be used to predict organizational breakdowns, and to evaluate alternative organizational changes to mitigate identified risks. VDT thus supports true "organizational engineering" for project teams.
Using atomic-level structure to probe protein function
Authors: Marvin Edelman, Vladimir Sobolev
Venue: ACM SIGBIO Newsletter (1999)

Molecular docking is relevant to drug design. Our analytical approach and some issues involved in docking and structure analysis are described.
Flexible and Risk-Sharing Supply Contracts Under Price Uncertainty
Authors: Chung-Lun Li, Panos Kouvelis
Venue: Management Science (1999)

We study supply contracts for deterministic demand but in an environment of uncertain prices. We develop valuation methodologies for different types of supply contracts. A "time-inflexible contract" requires the firm to specify not only how many units it will purchase, but also the timing of the purchase. A "time-flexible contract" allows the firm to specify the purchase amount over a given period of time without specifying the exact time of purchase. Other than time flexibility, the suppliers may offer "quantity flexibility" to the firm as well, i.e., purchase quantities could be within a prespecified quantity window. Finally, "risk-sharing" features can be incorporated in the contract in terms of the purchase price that the firm eventually pays to a supplier. Within a prespecified price window the firm pays the realized price, but outside of it the firm shares, in an agreed way, added costs or benefits. Given the structure of a supply contract, we study the firm's decision when to purchase and how many units in each purchase such that the expected net present value of the purchase cost plus inventory holding cost is minimized. We discuss optimal purchasing strategies for both time-flexible and time-inflexible contracts with risk-sharing features. Other interesting results include the analysis of two-supplier sourcing environments and the exploitation of quantity flexibility in such contracts. Our discussion illustrates how time flexibility, quantity flexibility, supplier selection, and risk sharing, when carefully exercised can effectively reduce the sourcing cost in environments of price uncertainty.
Deriving Array Distributions by Optimization Techniques
Authors: Thomas Rauber, Gudula Rünger
Venue: The Journal of Supercomputing (2000)

The paper presents a new method to derive data distributions for parallel computers with distributed memory organization by a mathematical optimization technique. Prerequisites for this approach are a parameterized data distribution and a rigorous performance prediction technique that allows us to derive runtime formulas containing the parameters of the data distribution. A mathematical optimization technique can then be used to determine the parameters in such a way that the total runtime is minimized, thus also minimizing the communication overhead and the load imbalance penalty. The method is demonstrated by using it to determine a data distribution for the LU decomposition of a matrix.
Minimizing cost of local variables access for DSP-processors
Authors: Erik Eckstein, Andreas Krall
Venue: Proceedings of the ACM SIGPLAN 1999 workshop on Languages, compilers, and tools for embedded systems (1999)

Recent work on compilation for DSP-processors deals with optimizing access to local variables of functions. The common way is to use one or more address registers as pointers into the functions stack frame and modify it with post modify addressing modes (which are sometimes the only addressing modes). Additionally to previous work we present an algorithm which assigns frame pointer values over a whole procedure. Our algorithm also deals with basic blocks, which have no accesses to local variables. The algorithm works with a new data structure, the control flow line graph, which is derived from the control flow graph. In our experiments, the algorithm showed improvements to similar algorithms.
The Accuracy of the Fractional Step Method
Authors: John C. Strikwerda, Young S. Lee
Venue: SIAM Journal on Numerical Analysis (1999)

We analyze the accuracy of the fractional step method of Kim and Moin [J. Comput. Phys., 59 (1985), pp. 308--323] for the incompressible Navier--Stokes equations. We show that the boundary conditions cannot be exactly satisfied in the projection step and that this limits the accuracy of the method. We also show that the pressure in any projection method can be at best first-order accurate. Our analysis is simpler and more direct than the previous analyses of this method. We also show that there is no numerical boundary layer for velocity or pressure, but there is one for the auxiliary pressure variable.
Mining for Attribute Definitions in a DistributedTwo-Layered DB System
Authors: Zbigniew W. Ras, Jan M. Żytkow
Venue: Journal of Intelligent Information Systems (2000)

Empirical equations are an important class of regularities that can be discovered in databases. We concentrate on the role of equations as definitions of attribute values. Such definitions can be used in many ways in a single database and for transfer of knowledge between databases. We present a quest for equations that can be used as definitions of an attribute in a given database. That quest triggers a discovery mechanism that specializes in searching recursively a system of databases and returns a set of partial definitions. We introduce the notion of shared operational semantics. It is founded on an equation-based system of partial definitions and it gives necessary foundations for designing local query answering systems in a distributed two-layered information system (D^2LIS). The knowledge exchange between two sites of D^2LIS may only improve an equation-based system of partial definitions at each of these sites. At the same time the shared operational semantics will better interpret user queries. Operational semantics augments the earlier developed semantics for rules used as attribute definitions. To put the shared operational semantics on a firm theoretical foundation we give a formal interpretation of queries which justifies empirical equations in their definitional role.
Finite Difference Methods for the Wide-Angle "Parabolic" Equation
Authors: Georgios Akrivis
Venue: SIAM Journal on Numerical Analysis (1998)

We consider a model initial and boundary value problem for the wide-angle "parabolic" equation Lur=icu of underwater acoustics, where L is a second-order differential operator in the depth variable z with depth- and range-dependent coefficients. We discretize the problem by the Crank--Nicolson finite difference scheme and also by the forward Euler method using nonuniform partitions both in depth and in range. Assuming that the problem admits a smooth solution, and L is invertible for all r under the posed boundary and interface conditions, we show stability of both schemes and derive error estimates.
The Kreiss Matrix Theorem on a General Complex Domain
Authors: Kim-Chuan Toh, Lloyd N. Trefethen
Venue: SIAM Journal on Matrix Analysis and Applications (1999)

Let A be a bounded linear operator in a Hilbert space $\H$ with spectrum $\Lam(A)$. The Kreiss matrix theorem gives bounds based on the resolvent norm $\norm{(zI-A)^{-1}}$ for $\norm{A^n}$ if $\Lam(A)$ is in the unit disk or for $\norm{e^{tA}}$ if $\Lam(A)$ is in the left half-plane. We generalize these results to a complex domain $\Ome$, giving bounds for $\norm{F_n(A)}$ if $\Lam(A) \subset \Ome$, where Fn denotes the nth Faber polynomial associated with $\Ome$. One of our bounds takes the form \til{\K}(\Ome) \; \leq \; 2\,\sup_{n} \, \norm{F_n(A)}, \qquad \norm{F_n(A)} \; \leq \; 2\,e \, (n+1) \, \til{\K}(\Ome), where $\til{\K}(\Ome)$ is the "Kreiss constant" defined by \til{\K}(\Ome) & = & \inf \left\{\, C \, : \, \norm{(zI-A)^{-1}} \; \leq \; C/\dist(z,\Ome) \ \forall \ z \not\in \Ome \right\}. By means of an inequality due originally to Bernstein, the second inequality can be extended to general polynomials pn. In the case where $\H$ is finite-dimensional, say, ${\rm dim}(\H) = N$, analogous results are also established in which ||Fn(A)|| is bounded in terms of N instead of n when the boundary of $\Ome$ is twice continuously differentiable.
Software performance estimation strategies in a system-level design tool
Authors: Jwahar R. Bammi, Wido Kruijtzer, Luciano Lavagno, Edwin Harcourt, Mihai T. Lazarescu
Venue: Proceedings of the eighth international workshop on Hardware/software codesign (2000)

High-level cost and performance estimation, coupled with a fast hardware/software co-simulation framework, is a key enabler to a fast embedded system design cycle. Unfortunately, the problem of deriving such estimates without a detailed implementation available is difficult.In this paper we describe two approaches to solve software cost and performance estimation problem, and how they are used in an embedded system design environment. A source-based approach uses compilation onto a virtual instruction set, and allows one to quickly obtain estimates without the need for a compiler for the target processor. An object-based approach translates the assembler generated by the target compiler to &ldquo;assembler-level,&rdquo; functionally equivalent t C. In both cases the code is annotated with timing and other execution related information (e.g., estimated memory accesses) and is used as a precise, yet fast, software simulation model. We contrast the precision and speed of these two techniques comparing them with those obtainable by a state-of-the-art cycle-based processor model.
Computer simulation for the evaluation of static and dynamic priority schemes in an ATM multiplexer with multimedia traffic
Authors: Saud Andrew Al-Barrak Adnan Andrew Nouh Saad Haj Bakry
Venue: International Journal of Network Management (1999)

This paper is concerned with the evaluation of static and dynamic priority schemes for ATM multiplexers using digital computer simulation and has three main parts. The first provides a basic computer simulation model of an ATM multiplexer with multimedia traffic streams that enables investigation of static and dynamic priority schemes. The second part uses the simulation model to study such schemes. The third part investigates combined dynamic space and dynamic time priorities to provide better performance for ATM multiplexers in comparison to using dynamic time priority only. Copyright &copy; 1999 John Wiley Sons, Ltd.
Implementing interface attachments based on surface representations
Authors: Dan R. Olsen,  Jr., Scott E. Hudson, Thom Verratti, Jeremy M. Heiner, Matt Phelps
Venue: Proceedings of the SIGCHI conference on Human factors in computing systems: the CHI is the limit (1999)

This paper describes an architecture for supporting interface attuchments - small interactive programs which are designed to augment the functionality of other applications. This architecture is designed to work with a diverse set of conventional applications, but require only a minimal set of hooks into those applications. In order to achieve this, the work described here concentrates on what we will call observational attachments, a subclass of attachments that operate primarily by observing and manipulating the surface representations of applications - that is the visual information that applications would normally display on the screen or print. These attachments can be thought of as looking over the shoulder of the user to assist with various tasks. By requiring very little modification to, or help from, the applications they augment, this approach supports the creation of a set of uniform services that can be applied across a more diverse set of applications than traditional approaches.
Computational aspects of resilient data extraction from semistructured sources (extended abstract)
Authors: Hasan Davulcu, Guizhen Yang, Michael Kifer, I. V. Ramakrishnan
Venue: Proceedings of the nineteenth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems (2000)

Automatic data extraction from semistructured sources such as HTML pages is rapidly growing into a problem of significant importance, spurred by the growing popularity of the so called &ldquo;shopbots&rdquo; that enable end users to compare prices of goods and other services at various web sites without having to manually browse and fill out forms at each one of these sites.The main problem one has to contend with when designing data extraction techniques is that the contents of a web page changes frequently, either because its data is generated dynamically, in response to filling out a form, or because of changes to its presentation format. This makes the problem of data extraction particularly challenging, since a desirable requirement of any data extraction technique is that it be &ldquo;resilient&rdquo;, i.e., using it we should always be able to locate the object of interest in a page (such as a form or an element in a table generated by a form fill-out) in spite of changes to the page's ntent and layout.In this paper we propose a formal computation model for developing resilient data extraction techniques from semistructured sources. Specifically we formalize the problem of data extraction as one of generating unambiguous extraction expressions, which are regular expressions with some additional structure. The problem of resilience is then formalized as one of generating a maximal extraction expression of this kind. We present characterization theorems for maximal extraction expressions, complexity results for testing them, and algorithms for synthesizing them.
Computer Simulation for the Evaluation of the IBM-SNA Congestion Management Method on GULFNET
Authors: Hamad V. Al-Sulaiym, Mohammed A. Al-Turaigi, Abdullah A. Al-Dhalaan, Saad Haj Bakry
Venue: International Journal of Network Management (1996)

The work presented in this article aims at using an available computer simulation package for the evaluation of the operation of the IBM-SNA-VRPC congestion management method on the present state of GULFNET, and a future design of the network that includes more nodes and provides higher reliability.