ppxscal/embedding_network huggingface dataset:
Software engineering education: R&ocirc;les of formal specification and design calculi
Authors: Dines Bjørner, Jorge R. Cuéllar
Venue: Annals of Software Engineering (1999)

This paper analyses current principles of software development: from domains via requirements to design. On the basis of this analysis we outline a structure and contents of professional software engineering. From this we extract some requirements to a university graduate (M.Sc.) curriculum in software engineering. We summarise the four software engineering axes that we wish to emphasize in this paper: software engineering as a responsible profession, abstraction, linguistics and logic, methodology, formal specification and design calculi, domain, requirements and software design engineering. We view (i) engineering as &lsquo;walking the bridge between science and technology&rsquo; &ndash; with engineers using mathematics as and when appropriate, (ii) methods as &lsquo;sets of principles for analysing problems and for selecting and applying techniques and tools in order to efficiently construct an efficient artifact (here software),&rsquo; and (iii) software engineering as consisting of &lsquo;domain engineering, requirements engineering and software design (engineering)&rsquo; &ndash; with software development comprising all these stages and teams of engineers specially educated in sub&dash;branches of software engineering. Since software engineering produces and consumes descriptions and since professional engineers create varieties of abstractions we conclude that they make use of varieties of formal specification languages and design calculi &ndash; to represent abstract and concrete descriptions and to calculate over and between these. The paper may be incomplete in not covering aspects of AI and knowledge based engineering. It also does not deal with the dimensioning and performance evaluation of hardware and software systems. The paper, in its attempt at a comprehensive analysis and proposal, is long. Our analysis subsumes that of ACM and IEEE &lsqb;ACM/IEEE&dash;CS June 1991&rsqb; to which we add&excl;
The Cost of Achieving the Best Portfolio in Hindsight
Authors: Erik Ordentlich, Thomas M. Cover
Venue: Mathematics of Operations Research (1998)

For a market with m assets consider the minimum, over all possible sequences of asset prices through time n, of the ratio of the final wealth of a nonanticipating investment strategy to the wealth obtained by the best constant rebalanced portfolio computed in hindsight for that price sequence. We show that the maximum value of this ratio over all nonanticipating investment strategies is Vn[&#931;2-nH(n1/n,...,nm/n)(n1!...nm!))] -1 where H(.) is the Shannon entropy, and we specify a strategy achieving it. The optimal ratio Vn is shown to decrease only polynomially in n, indicating that the rate of return of the optimal strategy converges uniformly to that of the best constant rebalanced portfolio determined with full hindsight. We also relate this result to the pricing of a new derivative security which might be called the hindsight allocation option.
The Bas-Relief Ambiguity
Authors: Peter N. Belhumeur, David J. Kriegman, Alan L. Yuille
Venue: International Journal of Computer Vision (1999)

When an unknown object with Lambertian reflectance is viewed orthographically, there is an implicit ambiguity in determining its 3-d structure: we show that the object&lsquo;s visible surface f(x, y) is indistinguishable from a &ldquo;generalized bas-relief&rdquo; transformation of the object&lsquo;s geometry, \bar f (x, y) &equals; &lambda;f(x, y) + &mu;x + &nu;y, and a corresponding transformation on the object&lsquo;s albedo. For each image of the object illuminated by an arbitrary number of distant light sources, there exists an identical image of the transformed object illuminated by similarly transformed light sources. This result holds both for the illuminated regions of the object as well as those in cast and attached shadows. Furthermore, neither small motion of the object, nor of the viewer will resolve the ambiguity in determining the flattening (or scaling) &lambda; of the object&lsquo;s surface. Implications of this ambiguity on structure recovery and shape representation are discussed.
Toward Correctly Rounded Transcendentals
Authors: Vincent Lefèvre, Jean-Michel Muller, Arnaud Tisserand
Venue: IEEE Transactions on Computers (1998)

The Table Maker's Dilemma is the problem of always getting correctly rounded results when computing the elementary functions. After a brief presentation of this problem, we present new developments that have helped us to solve this problem for the double-precision exponential function in a small domain. These new results show that this problem can be solved, at least for the double-precision format, for the most usual functions.
Future Polynomial Regularization of Ill-Posed Volterra Equations
Authors: Aaron C. Cinzori, Patricia K. Lamm
Venue: SIAM Journal on Numerical Analysis (2000)

We examine a new discrete method for regularizing ill-posed Volterra problems. Unlike many classical regularization techniques (such as Tikhonov regularization), this method preserves the Volterra (causal) nature of the problem allowing the regularized solution to be produced sequentially in near real time as data arrives. We analyze the method and, for an important class of Volterra problems, prove that regularized solutions converge to the true solution at the best possible rate with respect to error in the data.In fact, the future polynomial regularization method discussed here may be applied to quite general operator equations provided that the operator may be discretized by a lower-triangular matrix of Toeplitz type. This enlarges the class of operator equations that may be approximated using the method, but it also introduces degenerate situations in which the future polynomial method is no more regularizing than an ordinary discretization method. We characterize these degenerate cases and argue that we are unlikely to see them for the problems of interest here. In particular, such degeneracies cannot occur for the class of Volterra problems for which we are able to prove the future polynomial method converges.Finally we present numerical evidence that this method works well in the recovery of sharp and discontinuous features in the true solution, features that can be oversmoothed by classical regularization techniques.
Nonlinear Decision Weights in Choice Under Uncertainty
Authors: George Wu, Richard Gonzalez
Venue: Management Science (1999)

In most real-world decisions, consequences are tied explicitly to the outcome of events. Previous studies of decision making under uncertainty have indicated that the psychological weight attached to an event, called a decision weight, usually differs from the probability of that event. We investigate two sources of nonlinearity of decision weights: subadditivity of probability judgments, and the overweighting of small probabilities and underweighting of medium and large probabilities. These two sources of nonli nearity are combined into a two-stage model of choice under uncertainty. In the first stage, events are taken into subjective probability judgments, and the second stage takes probability judgments into decision weights. We then characterize the curvature of the decision weights by extending a condition employed by Wu and Gonzalez (1996) in the domain of risk to the domain of uncertainty and show that the nonlinearity of decision weights can be decomposed into subadditivity of probability judgments and the curvature of the probability weighting function. Empirical tests support the proposed two-stage model and indicate that decision weights are concave then convex. More specifically, our results lend support for a new property of subjective probability ju dgments, interior additivity (subadditive at the boundaries, but additive away from the boundaries), and show that the probability weighting function is inverse S-shaped as in Wu and Gonzalez (1996).
Organizational Form and Efficiency: the Coexistence of Stock and Mutual Property-Liability Insurers
Authors: J. David Cummins, Mary A. Weiss, Hongmin Zi
Venue: Management Science (1999)

This article introduces a new approach, cross-frontier analysis, for estimating the relative efficiency of alternative organizational forms in an industry. The technique is illustrated by analyzing a sample of stock and mutual property-liability insurers using nonparametric frontier efficiency methods. Cross-frontier analysis measures the relative efficiency of each organizational form by computing the efficiency of each stock (mutual) firm relative to a reference set consisting of all mutual (stock) firms. We test agency-theoretic hypotheses about organizational form, including the managerial discretion and expense preference hypotheses. The results indicate that stocks and mutuals are operating on separate production and cost frontiers and thus represent distinct technologies. Consistent with the managerial discretion hypothesis, the stock technology dominates the mutual technology for producing stock outputs and the mutual technology dominates the stock technology for producing mutual outputs. However, consistent with the expense preference hypothesis, the stock cost frontier dominates the mutual cost frontier. Our findings thus suggest a richer interpretation of organizational form than provided by previous researchers.
Influence of Circuit Imperfections on the Performance of DACs
Authors: J. Jacob Wikner, Nianxiong Tan
Venue: Analog Integrated Circuits and Signal Processing (1999)

Digital-to-analog converters are crucial building blocks for telecommunication applications. For this kind of applications, the traditional static performance requirements do not apply. The dynamic performance is of the greatest importance. This paper discusses the aspects of the performance of CMOS digital-to-analog converters and models the influence of non-idealities of circuit components (such as output impedance, mismatch, circuit noise, etc.) on the frequency-domain performance. Both deterministic and stochastic effects are modeled. The purpose of this modeling is to provide an insightful design guide for high dynamic performance CMOS digital-to-analog converters.
Structured Total Least Norm for Nonlinear Problems
Authors: J. B. Rosen, Haesun Park, John Glick
Venue: SIAM Journal on Matrix Analysis and Applications (1999)

An extension of the recently developed structured total least norm (STLN) problem formulation is described for solving a class of nonlinear parameter estimation problems. STLN is a problem formulation for obtaining an approximate solution to the overdetermined linear system $Ax \approx b$ preserving the given affine structure in A or [A | b], where errors can occur in both the vector b and the matrixA. The approximate solution can be obtained to minimize the error in the Lp norm, where p = 1, 2, \mbox{ or } \infty$. In the extension of STLN to nonlinear problems, the elements of A may be differentiable nonlinear functions of a parameter vector, whose value needs to be approximated. We call this extension structured nonlinear total least norm (SNTLN). The SNTLN problem is formulated and its solution by a modified STLN algorithm is described. Optimality conditions and convergence for the 2-norm case are presented. Computational tests were carried out on an overdetermined system with Vandermonde structure and on two nonlinear parameter estimation problems. In these problems, both the coefficients and the unknown parameters were to be determined. The computational results demonstrate that the SNTLN algorithm recovers good approximations to the correct values of both the coefficients and parameters, in the presence of noise in the data and poor initial estimates of the parameters. It is also shown that the SNTLN algorithm with the 1-norm minimization is robust with respect to outliers in the data.
The associative-skew clock routing problem
Authors: Yu Chen, Andrew B. Kahng, Gang Qu, Alexander Zelikovsky
Venue: Proceedings of the 1999 IEEE/ACM international conference on Computer-aided design (1999)

We introduce the associative skew clock routing problem, which seeks a clock routing tree such that zero skew is preserved only within identified groups of sinks. The associative skew problem is easier to address within current EDA frameworks than useful-skew (skew-scheduling) approaches, and defines an interesting tradeoff between the traditional zero-skew clock routing problem (one sink group) and the Steiner minimum tree problem (n sink groups). We present a set of heuristic building blocks, including an efficient and optimal method of merging two zero-skew trees such that zero skew is preserved within the sink sets of each tree. Finally, we list a number of open issues for research and practical application.
A case for dynamic sender-based reservations in the Internet
Authors: Paul Patrick White, Jon Crowcroft
Venue: Journal of High Speed Networks (1998)

In this paper we discuss the need for resource reservation in the Internet and examine some of the strengths and weaknesses of RSVP, which is currently the most popular of Internet reservation protocols that have been developed. We also discuss some alternative reservation protocols for packet networks, in particular the ATM Block Transfer (ABT) reservation protocol that has been designed for use in Asynchronous Transfer Mode (ATM) networks and which uses in-line control packets to modify reservations on the fly to achieve very efficient bandwidth utilisation. Finally, we present a proposal for a new reservation protocol, known as DRP (Dynamic Reservation Protocol) which combines many of the strengths of RSVP and ABT with few of the weaknesses to achieve a highly bandwidth-efficient reservation mechanism with excellent scalability with regards to round trip time, data rate and number of hosts.
An Estimation of Complexity and Computational Costs for Vertical Block-Cyclic Distributed Parallel LU Factorization
Authors: Toshiyuki Imamura
Venue: The Journal of Supercomputing (2000)

The Vertical Block&ndash;cyclic Distributed Parallel LU Factorization Method (VBPLU) is effectively processed on a distributed memory parallel computer. VBPLU is based on the two techniques, the block algorithm and the aggregation of communications. Since startup time dominates the data communication and the aggregation reduces communication isssues, the total performance has been much improved. Furthermore this method uses long vectors so that it is also advantageous on vector processors. In this paper, we have constructed a modeling of VBPLU using a simplified LogGP model with analytical formulae, and estimated accurately the computational cost taking into account load distributions caused by data layout and process mapping. Some knowledge for optimization of block algorithm has been obtained. Our estimations have been verified through numerical experiments on three different distributed memory parallel computers.
Finite-state code generation
Authors: Christopher W. Fraser, Todd A. Proebsting
Venue: ACM SIGPLAN Notices (1999)

This paper describes GBURG, which generates tiny, fast code generators based on finite-state machine pattern matching. The code generators translate postfix intermediate code into machine instructions in one pass (except, of course, for backpatching addresses). A stack-based virtual machine---known as the Lean Virtual Machine (LVM)---tuned for fast code generation is also described. GBURG translates the two-page LVM-to-x86 specification into a code generator that fits entirely in an 8 KB I-cache and that emits x86 code at 3.6 MB/set on a 266-MHz P6. Our just-in-time code generator translates and executes small benchmarks at speeds within a factor of two of executables derived from the conventional compile-time code generator on which it is based.
Accurate Computation of the Product-Induced Singular Value Decomposition with Applications
Authors: Zlatko Drmac
Venue: SIAM Journal on Numerical Analysis (1998)

We present a new algorithm for floating-point computation of the singular value decomposition (SVD) of the product $B^{\tau}C$, where $B$ and $C$ are full row rank matrices. The algorithm replaces the pair $(B,C)$ with an equivalent pair $(B',C')$ and then it uses the Jacobi SVD algorithm to compute the SVD of the explicitly computed matrix $B'^{\tau}C'$. In this way, each nonzero singular value $\sigma$ is approximated with some $\sigma+\delta\sigma$, where the relative error $|\delta\sigma|/\sigma$ is, up to a factor of the dimensions, of order \boldmath${\varepsilon}$\unboldmath $\{\min_{\Delta\in{\cal D}}\kappa_2(\Delta B)+ \min_{\Delta\in{\cal D}} \kappa_2(\Delta C)\}$, where ${\cal D}$ denotes the set of diagonal nonsingular matrices, $\kappa_2(\cdot)$ denotes the spectral condition number, and \boldmath${\varepsilon}$\unboldmath\ is the roundoff unit of floating-point arithmetic. The new algorithm is applied to the eigenvalue problem $HM x = \lambda x$ with symmetric positive definite $H$ and $M$. It is shown that each eigenvalue $\lambda$ is computed with high relative accuracy and that the relative error $|\delta\lambda|/\lambda$ of the computed approximation $\lambda+\delta\lambda$ is, up to a factor of the dimension, of order \boldmath${\varepsilon}$\unboldmath$\{\min_{\Delta\in{\cal D}}\kappa_2(\Delta H\Delta) + \min_{\Delta\in{\cal D}}\kappa_2(\Delta M\Delta)\}$. The new algorithm can also be used for accurate SVD computation of a single matrix $G$ that admits an accurate factorization $G=B^{\tau}C$.
Working with Cisco access lists
Authors: Gilbert A. Held
Venue: International Journal of Network Management (1999)

The first line of defense of a network is accomplished through the creation of a router access list. This paper examines the creation and application of Cisco access lists and explains why they must be applied to an interface to go into effect. Copyright &copy; 1999 John Wiley Sons, Ltd.
The Web as a graph
Authors: Ravi Kumar, Prabhakar Raghavan Sridhar Rajagopalan D. Sivakumar Andrew Tompkins Eli Upfal
Venue: Proceedings of the nineteenth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems (2000)

The pages and hyperlinks of the World-Wide Web may be viewed as nodes and edges in a directed graph. This graph has about a billion nodes today, several billion links, and appears to grow exponentially with time. There are many reasons&mdash;mathematical, sociological, and commercial&mdash;for studying the evolution of this graph. We first review a set of algorithms that operate on the Web graph, addressing problems from Web search, automatic community discovery, and classification. We then recall a number of measurements and properties of the Web graph. Noting that traditional random graph models do not explain these observations, we propose a new family of random graph models.
Tradeoffs and design of an ultra low power UHF transceiver integrated in a standard digital CMOS process
Authors: Alain-Serge Porret, Thierry Melly, E. A. Vittoz, C. C. Enz
Venue: Proceedings of the 2000 international symposium on Low power electronics and design (2000)

A broad range of high-volume consumer applications require low-power, battery operated, wireless microsystems and sensors. These systems should conciliate a sufficient battery lifetime with reduced dimensions, low cost and versatility. The design of such systems highlights many tradeoffs between performances, lifetime, cost and power consumption. Also, special circuit and design techniques are needed to comply with the reduced supply voltage (down to 1V).These considerations are illustrated by design examples taken from a transceiver chip realized in a standard 0.5&mgr;m digital CMOS process. The chip is dedicated to a distributed sensors network and is based on a direct-conversion architecture. The circuit prototype operates in the 434 MHz ISM band and consumes only 1mW in receive mode. It achieves a -95dBm sensitivity for a data rate of 24kbit/s. The transmitter section is designed for 0dBm output power under the minimum 1V supply, with a global efficiency higher than 15%.
Cluster reserves: a mechanism for resource management in cluster-based network servers
Authors: Mohit Aron, Peter Druschel, Willy Zwaenepoel
Venue: ACM SIGMETRICS Performance Evaluation Review (2000)

In network (e.g., Web) servers, it is often desirable to isolate the performance of different classes of requests from each other. That is, one seeks to achieve that a certain minimal proportion of server resources are available for a class of requests, independent of the load imposed by other requests. Recent work demonstrates how to achieve this performance isolation in servers consisting of a single, centralized node; however, achieving performance isolation in a distributed, cluster based server remains a problem.This paper introduces a new abstraction, the cluster reserve, which represents a resource principal in a cluster based network server. We present a design and evaluate a prototype implementation that extends existing techniques for performance isolation on a single node server to cluster based servers.In our design, the dynamic cluster-wide resource management problem is formulated as a constrained optimization problem, with the resource allocations on individual machines as independent variables, and the desired cluster-wide resource allocations as constraints. Periodically collected resource usages serve as further inputs to the problem.Experimental results show that cluster reserves are effective in providing performance isolation in cluster based servers. We demonstrate that, in a number of different scenarios, cluster reserves are effective in ensuring performance isolation while enabling high utilization of the server resources.
A new family of authentication protocols
Authors: Ross Anderson, Francesco Bergadano, Bruno Crispo, Jong-Hyeon Lee, Charalampos Manifavas, Roger Needham
Venue: ACM SIGOPS Operating Systems Review (1998)

We present a related family of authentication and digital signature protocols based on symmetric cryptographic primitives which perform substantially better than previous constructions. Previously, one-time digital signatures based on hash functions involved hundreds of hash function computations for each signature; we show that given online access to a timestamping service, we can sign messages using only two computations of a hash function. Previously, techniques to sign infinite streams involved one such one-time signature for each message block; we show that in many realistic scenarios a small number of hash function computations is sufficient. Previously, the Diffie Hellman protocol enabled two principals to create a confidentiality key from scratch: we provide an equivalent protocol for integrity, which enables two people who do not share a secret to set up a securely serialised channel into which attackers cannot subsequently intrude. In addition to being of potential use in real applications, our constructions also raise interesting questions about the definition of a digital signature, and the relationship between integrity and authenticity.
Modeling Emergency Supply Flexibility in a Two-Echelon Inventory System
Authors: Patrik Alfredsson, Jos Verrijdt
Venue: Management Science (1999)

We consider a two-echelon inventory system for service parts. To obtain high service levels at a low cost we allow not only for normal supply of parts but also for emergency supply options in terms of lateral transshipments and direct deliveries. After presenting the strategy we use for satisfying customer demand, we construct an analytical model that we use to calculate relevant performance measures. Simulation shows that our model produces accurate estimates, and that the performance of the inventory system is insensitive to the lead-time distribution. After introducing a cost structure we show that the strategy we propose can result in considerable savings when compared to using only normal supply. Comparison of the results of our model with the results of other models indicates that the combined use of lateral transshipments and direct deliveries can lead to significant cost savings.