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  • Articles  (6,347)
  • Springer  (6,347)
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  • 1995-1999  (6,347)
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  • 1999  (3,545)
  • 1996  (2,802)
  • Computer Science  (6,347)
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  • Articles  (6,347)
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  • 1
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    Mathematical programming 85 (1999), S. 135-156 
    ISSN: 1436-4646
    Keywords: Key words: bound constrained quadratic programming – Huber’s M–estimator – condition estimation – Newton iteration – factorization update
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: 1 , the smallest eigenvalue of a symmetric, positive definite matrix, and is solved by Newton iteration with line search. The paper describes the algorithm and its implementation including estimation of λ1, how to get a good starting point for the iteration, and up- and downdating of Cholesky factorization. Results of extensive testing and comparison with other methods for constrained QP are given.
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  • 2
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    Mathematical programming 85 (1999), S. 35-49 
    ISSN: 1436-4646
    Keywords: Key words: bimatrix game – quasi-strict equilibrium ; Mathematics Subject Classification (1991): 90D05
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
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  • 3
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    Mathematical programming 85 (1999), S. 107-134 
    ISSN: 1436-4646
    Keywords: Key words: equilibrium constraints – variational inequality problems – strong monotonicity – optimality conditions – global convergence ; Mathematics Subject Classification (1991): 90C30, 90C33, 65K05
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
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  • 4
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    Mathematical programming 85 (1999), S. 363-377 
    ISSN: 1436-4646
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: 1 ,...,Am are true, then at least ℓ of the propositions B1,...,Bn are true. The main result of the paper is that the procedure in fact provides a convex hull description.
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  • 5
    ISSN: 1436-4646
    Keywords: Key words: maximum-entropy sampling – branch and bound – nonlinear programming
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  • 6
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    Mathematical programming 85 (1999), S. 259-276 
    ISSN: 1436-4646
    Keywords: Key words: linear complementary problems – Q-matrices – polyhedral combinatorics – triangulations of point configurations – 0-1 polytopes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: T (Mx+q)=0, Mx+q≥0, x≥0 has a solution. We explain how one can use the polyhedral structure of the set of all triangulations of a finite point set to determine if an n×n matrix M is a Q-matrix. Our implementation of the algorithm is practical for deciding the Q-nature for all M with n≤8.
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  • 7
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    Mathematical programming 85 (1999), S. 593-616 
    ISSN: 1436-4646
    Keywords: Key words: concave optimization – conical algorithms –ω-subdivisions Mathematics Subject Classification (1991): 90C26, 65K05
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. In this paper the problem of finding the global optimum of a concave function over a polytope is considered. A well-known class of algorithms for this problem is the class of conical algorithms. In particular, the conical algorithm based on the so called ω-subdivision strategy is considered. It is proved that, for any given accuracy ε〉0, this algorithm stops in a finite time by returning an ε-optimal solution for the problem, while it is convergent for ε=0.
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  • 8
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    Mathematical programming 85 (1999), S. 439-467 
    ISSN: 1436-4646
    Keywords: Mathematics Subject Classification (1991): 90C11
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. We investigate strong inequalities for mixed 0-1 integer programs derived from flow cover inequalities. Flow cover inequalities are usually not facet defining and need to be lifted to obtain stronger inequalities. However, because of the sequential nature of the standard lifting techniques and the complexity of the optimization problems that have to be solved to obtain lifting coefficients, lifting of flow cover inequalities is computationally very demanding. We present a computationally efficient way to lift flow cover inequalities based on sequence independent lifting techniques and give computational results that show the effectiveness of our lifting procedures.
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  • 9
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    Mathematical programming 85 (1999), S. 525-540 
    ISSN: 1436-4646
    Keywords: Key words: semidefinite programming – perturbation theory – Kantorovi theory – condition number Mathematics Subject Classification (1991): 90C31, 90C25, 90C05
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: theory. This approach also quantifies the size of permissible perturbations. We include a discussion of these results for block diagonal semidefinite programs, of which linear programming is a special case.
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  • 10
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    Mathematical programming 86 (1999), S. 219-223 
    ISSN: 1436-4646
    Keywords: Key words: linear programming – computational complexity – complexity measure Mathematics Subject Classification (1991): 90C05, 90C60, 68Q25
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. Given an m×n integer matrix A of full row rank, we consider the problem of computing the maximum of ∥B -1 A∥2 where B varies over all bases of A. This quantity appears in various places in the mathematical programming literature. More recently, logarithm of this number was the determining factor in the complexity bound of Vavasis and Ye’s primal-dual interior-point algorithm. We prove that the problem of approximating this maximum norm, even within an exponential (in the dimension of A) factor, is NP-hard. Our proof is based on a closely related result of L. Khachiyan [1].
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  • 11
    ISSN: 1436-4646
    Keywords: Key words: non-interior point method – complementarity problem – smoothing function – homotopy method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. We propose a class of non-interior point algorithms for solving the complementarity problems(CP): Find a nonnegative pair (x,y)∈ℝ 2n satisfying y=f(x) and x i y i =0 for every i∈{1,2,...,n}, where f is a continuous mapping from ℝ n to ℝ n . The algorithms are based on the Chen-Harker-Kanzow-Smale smoothing functions for the CP, and have the following features; (a) it traces a trajectory in ℝ 3n which consists of solutions of a family of systems of equations with a parameter, (b) it can be started from an arbitrary (not necessarily positive) point in ℝ 2n in contrast to most of interior-point methods, and (c) its global convergence is ensured for a class of problems including (not strongly) monotone complementarity problems having a feasible interior point. To construct the algorithms, we give a homotopy and show the existence of a trajectory leading to a solution under a relatively mild condition, and propose a class of algorithms involving suitable neighborhoods of the trajectory. We also give a sufficient condition on the neighborhoods for global convergence and two examples satisfying it.
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  • 12
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    Mathematical programming 86 (1999), S. 41-50 
    ISSN: 1436-4646
    Keywords: Key words: resolvent method – proximal point method – bundle method – bundle-trust region method – subgradient Mathematics Subject Classification (1991): 90C25, 49M45
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. This paper establishes a linear convergence rate for a class of epsilon-subgradient descent methods for minimizing certain convex functions on ℝ n . Currently prominent methods belonging to this class include the resolvent (proximal point) method and the bundle method in proximal form (considered as a sequence of serious steps). Other methods, such as a variant of the proximal point method given by Correa and Lemaréchal, can also fit within this framework, depending on how they are implemented. The convex functions covered by the analysis are those whose conjugates have subdifferentials that are locally upper Lipschitzian at the origin, a property generalizing classical regularity conditions.
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  • 13
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    Mathematical programming 86 (1999), S. 387-415 
    ISSN: 1436-4646
    Keywords: Key words: semi-infinite optimization – reduction approach – stationary point – strong stability – extended Mangasarian-Fromovitz constraint qualification Mathematics Subject Classification (1991): 90C30, 90C31, 90C34, 49M39
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. The paper deals with semi-infinite optimization problems which are defined by finitely many equality constraints and infinitely many inequality constraints. We generalize the concept of strongly stable stationary points which was introduced by Kojima for finite problems; it refers to the local existence and uniqueness of a stationary point for each sufficiently small perturbed problem, where perturbations up to second order are allowed. Under the extended Mangasarian-Fromovitz constraint qualification we present equivalent conditions for the strong stability of a considered stationary point in terms of first and second derivatives of the involved functions. In particular, we discuss the case where the reduction approach is not satisfied.
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  • 14
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    Mathematical programming 86 (1999), S. 313-334 
    ISSN: 1436-4646
    Keywords: Key words: linear programming – potential functions – infeasible-interior-point methods – homogeneity – self-dual
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
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  • 15
    ISSN: 1436-4646
    Keywords: Key words: basis recovery – partition – principal pivot transforms – Balinski-Tucker tableaus – quadratic programming – linear complementarity problems – interior point methods – sufficient matrices – crossover – Criss-Cross method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. Optimal solutions of interior point algorithms for linear and quadratic programming and linear complementarity problems provide maximally complementary solutions. Maximally complementary solutions can be characterized by optimal partitions. On the other hand, the solutions provided by simplex–based pivot algorithms are given in terms of complementary bases. A basis identification algorithm is an algorithm which generates a complementary basis, starting from any complementary solution. A partition identification algorithm is an algorithm which generates a maximally complementary solution (and its corresponding partition), starting from any complementary solution. In linear programming such algorithms were respectively proposed by Megiddo in 1991 and Balinski and Tucker in 1969. In this paper we will present identification algorithms for quadratic programming and linear complementarity problems with sufficient matrices. The presented algorithms are based on the principal pivot transform and the orthogonality property of basis tableaus.
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  • 16
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    Mathematical programming 86 (1999), S. 417-431 
    ISSN: 1436-4646
    Keywords: Mathematics Subject Classification (1991): 90A11, 90B50, 90C90, 90D65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. We study the following decision-making scenario: A linear program is solved by a set of agents arranged hierarchically in a tree, where each agent decides the level of certain variables, and has a distinct objective function, known to all agents. Authority is reflected in two ways: Agents higher in the tree set their variables first; and agents that are siblings in the tree resolve their game by focusing on the Nash equilibrium that is optimum for the agent above them. We give a necessary and sufficient condition for such a hierarchy to be efficient (i.e., to have perfect coordination, to ultimately optimize the objective of the firm). We study problems related to designing a hierarchy (assigning decision makers to positions in the tree) in order to achieve efficiency or otherwise optimize coordination.
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  • 17
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    Mathematical programming 86 (1999), S. 533-563 
    ISSN: 1436-4646
    Keywords: Key words: generalized linear complementarity problem – non-interior continuation method – Newton method – Q-quadratical convergence Mathematics Subject Classification (1991): 90C33
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. In this paper, we propose a non-interior continuation method for solving generalized linear complementarity problems (GLCP) introduced by Cottle and Dantzig. The method is based on a smoothing function derived from the exponential penalty function first introduced by Kort and Bertsekas for constrained minimization. This smoothing function can also be viewed as a natural extension of Chen-Mangasarian’s neural network smooth function. By using the smoothing function, we approximate GLCP as a family of parameterized smooth equations. An algorithm is presented to follow the smoothing path. Under suitable assumptions, it is shown that the algorithm is globally convergent and local Q-quadratically convergent. Few preliminary numerical results are also reported.
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  • 18
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    Mathematical programming 86 (1999), S. 463-473 
    ISSN: 1436-4646
    Keywords: Key words: semidefinite relaxations – quadratic programming Mathematics Subject Classification (1991): 20E28, 20G40, 20C20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. We demonstrate that if A 1,...,A m are symmetric positive semidefinite n×n matrices with positive definite sum and A is an arbitrary symmetric n×n matrix, then the relative accuracy, in terms of the optimal value, of the semidefinite relaxation $$\max_X\{\Tr(AX)\mid\, \Tr(A_iX)\le1,\,\,i=1,...,m;\,X\succeq0\} \eqno{\hbox{(SDP)}}$$ of the optimization program $$x^TAx\to\max\mid\, x^TA_ix\le 1,\,\,i=1,...,m \eqno{\hbox{(P)}}$$ is not worse than $$1-\frac{1}{{2\ln(2m^2)}}$$ . It is shown that this bound is sharp in order, as far as the dependence on m is concerned, and that a~feasible solution x to (P) with $$x^TAx\ge \frac{{\Opt(\hbox{{\rm SDP}})}}{{2\ln(2m^2)}} \eqno{(*)}$$ can be found efficiently. This somehow improves one of the results of Nesterov [4] where bound similar to (*) is established for the case when all Ai are of rank 1.
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  • 19
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    Mathematical programming 86 (1999), S. 161-185 
    ISSN: 1436-4646
    Keywords: Mathematics Subject Classification (1991): 90C10
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. This paper considers the precedence constrained knapsack problem. More specifically, we are interested in classes of valid inequalities which are facet-defining for the precedence constrained knapsack polytope. We study the complexity of obtaining these facets using the standard sequential lifting procedure. Applying this procedure requires solving a combinatorial problem. For valid inequalities arising from minimal induced covers, we identify a class of lifting coefficients for which this problem can be solved in polynomial time, by using a supermodular function, and for which the values of the lifting coefficients have a combinatorial interpretation. For the remaining lifting coefficients it is shown that this optimization problem is strongly NP-hard. The same lifting procedure can be applied to (1,k)-configurations, although in this case, the same combinatorial interpretation no longer applies. We also consider K-covers, to which the same procedure need not apply in general. We show that facets of the polytope can still be generated using a similar lifting technique. For tree knapsack problems, we observe that all lifting coefficients can be obtained in polynomial time. Computational experiments indicate that these facets significantly strengthen the LP-relaxation.
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  • 20
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    Computing 56 (1996), S. 29-46 
    ISSN: 1436-5057
    Keywords: 94A15 ; Optimal and heuristic encoding ; shortest paths ; textual substitution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Es werden Text-Komprimierungsprobleme behandelt, bei denen Teilworte durch Codeworte ersetzt werden, sodaß der ursprüngliche Text durch eine kürzere Codesequenz repräsentiert wird. Das geschieht mit Hilfe eines statischen Wörterbuchs. Wir führen eine neue effiziente on-line Heuristik ein, welche die lokale Komprimierungsrate maximiert. Von diesem fractional greedy Verfahren wird das Verhalten im schlechtesten Fall für verschiedene Typen von Wörterbüchern untersucht.
    Notes: Abstract Text-compression problems are considered where substrings are substitued by code-words according to a static dictionary such that the original text is encoded by a shorter code sequence. We introduce a new efficient on-line heuristic which locally maximizes the compaction ratio. The worst-case behaviour of this fractional greedy heuristic is investigated for several types of dictionaries.
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  • 21
    ISSN: 1436-5057
    Keywords: 65 L 05 ; Rosenbrock-type methods ; quasilinear-implicit differential equations ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Bei der Lösung quasilinear-impliziter ODEs mittels Rosenbrock-Typ-Methoden können trotz guter Stabilitätseigenschaften (A- bzw. L-Stabilität) des Grundverfahrens Stabilitätsprobleme auftreten. Diese Schwierigkeiten sind auf Ungenauigkeiten bei der Berechnung künstlich eingeführter Komponenten (Überführung in DAEs) zurückzuführen. Die Arbeit untersucht die Ursachen für diese Effekte und zeigt Möglichkeiten, diese zu überwinden.
    Notes: Abstract The solution of quasilinear-implicit ODEs using Rosenbrock type methods may suffer from stability problems despite stability properties such as A-stability or L-stability, respectively. These problems are caused by inexact computation of artificial introduced components (transformation to DAE system). The paper investigates the source of the numerical difficulties and shows modifications to overcome them.
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  • 22
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    Computing 56 (1996), S. 61-85 
    ISSN: 1436-5057
    Keywords: 65N55 ; 65N38 ; Boundary integral equations ; domain decomposition ; Schwarz methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Es werden zwei Gebietszerlegungsalgorithmen für die numerische Behandlung von Randintegralgleichungen der ersten Art untersucht. Die Verfahren beruhen auf derh-Version der Galerkinmethode für Randelemente, auf die die multiplikative und die additive Schwarz-Methode angewandt werden. Für zweidimensionale Probleme wird gezeigt, daß die Konvergenzraten beider Methoden unabhängig von der Anzahl der Unbekannten sind. Numerische Resultate für einfache zweidimensionale und dreidimensionale Modellprobleme, die von der Laplace-Gleichung mit Dirichlet oder Neumann-Randbedingungen stammen, werden diskutiert. Eine Gebietszerlegungsstrategie für den Fall vieler Teilgebiete wird anhand eines dreidimensionalen Schirmproblems demonstriert.
    Notes: Abstract This paper investigates two domain decomposition algorithms for the numerical solution of boundary integral equations of the first kind. The schemes are based on theh-type boundary element Galerkin method to which the multiplicative and the additive Schwarz methods are applied. As for twodimensional problems, the rates of convergence of both methods are shown to be independent of the number of unknowns. Numerical results for standard model problems arising from Laplaces' equation with Dirichlet or Neumann boundary conditions in both two and three dimensions are discussed. A multidomain decomposition strategy is indicated by means of a screen problem in three dimensions, so as to obtain satisfactory experimental convergence rates.
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    Computing 56 (1996), S. 1-27 
    ISSN: 1436-5057
    Keywords: 65F10 ; 65H10 ; 65N22 ; 65N30 ; 65N55 ; Semiconductor device ; drift-diffusion equations ; finite element methods ; Gummel's method ; preconditioned conjugate gradient methods ; Schur complement ; domain decomposition massively parallel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Diese Arbeit enthält die Beschreibung, Analyse und Implementierung eines parallelen iterativen Verfahrens zur Lösung der stationären Drift-Diffusions-Gleichung für ein zweidimensionales Halbleitermodell. Die Unbekannten unseres Modells sind das elektrostatische Potential und die Quasi-Fermi-Potentiale der Elektronen und Löcher. Unsere Diskretisierung verwendet die Finite-Element-Methode mit ‘mass limping’ für das elektrostatische Potential und hybride Elemente mit lokaler Stromerhaltung für die Kontinuitätsgleichung. Zur Lösung der entsprechenden nichtlinearen Gleichungen wird eine Version des Gummel-Algorithmus verwendet, der lediglich die Lösung positiv definiter, symmetrischer linearer Gleichungssysteme erfordert. Wir zeigen, daß diese Methode eine Konvergenzrate besitzt, die nur logarithmisch von der Schrittweite abhängt. Die (inneren) nichtlinearen Löser der elektrostatischen Potentialgleichung konvergieren gitterunabhängig quadratisch. Wir beschreiben auch eine Implementierung auf einem MasPar MP-1-Parallelrechner, wobei die auftretenden linearen Systeme mit einem vorkonditionierten cg-Verfahren approximiert werden. Gebietszerlegungsmethoden werden eingesetzt, um die notwendige Matrix-Vektor-Multiplikation zu parallelisieren und Vorkonditionierer dieser schlechtkonditionierten Systeme zu erstellen. Die vorkonditionierten linearen Löser haben ebenfalls eine Konvergenzrate, die logarithmisch vom Verhältnis Teilgebietsgröße zu Schrittweite abhängt und welche robust ist bezüglich stark variierenden Koeffizientenfunktionen des zugrundeliegenden elliptischen Operators. Experimente auf einem Parallelrechner werden diskutiert.
    Notes: Abstract In this paper we describe, analyse and implement a parallel iterative method for the solution of the steady-state drift diffusion equations governing the behaviour of a semiconductor device in two space dimensions. The unknowns in our model are the electrostatic potential and the electron and hole quasi-Fermi potentials. Our discretisation consists of a finite element method with mass lumping for the electrostatic potential equation and a hybrid finite element with local current conservation properties for the continuity equations. A version of Gummel's decoupling algorithm which only requires the solution of positive definite symmetric linear systems is used to solve the resulting nonlinear equations. We show that this method has an overall rate of convergence which only degrades logarithmically as the mesh is refined. Indeed the (inner) nonlinear solves of the electrostatic potential equation converge quadratically, with a mesh independent asymptotic constant. We also describe an implementation on a MasPar MP-1 data parallel machine, where the required linear systems are solved by the preconditioned conjugate gradient method. Domain decomposition methods are used to parallelise the required matrix-vector multiplications and to build preconditioners for these very poorly-conditioned systems. Our preconditioned linear solves also have a rate of convergence which degrades logarithmically as the grid is refined relative to subdomain size, and their performance is resilient to the severe layers which arise in the coefficients of the underlying elliptic operators. Parallel experiments are given.
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    Computing 56 (1996), S. 87-93 
    ISSN: 1436-5057
    Keywords: 41A15 ; 65D30 ; Integration formulas ; iterated cubic splines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Wir erarbeiten eine Anwendung iterativer kubischer Splines auf die numerische Integrationsformeln. Wir geben einige numerische Beispiele, um den Nutzen unserer Methoden zu illustrieren.
    Notes: Abstract We consider an application of iterated cubic splines to numerical integration formulas. Some numerical examples are given to illustrate usefulness of our methods.
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  • 25
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    Computing 56 (1996), S. 95-104 
    ISSN: 1436-5057
    Keywords: 68M20 ; Probabilistic algorithm ; online scheduling ; interval ; busy time
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Wir betrachten das Problem der Zuteilung von Aufgaben bestimmter Rechenzeit auf einem Rechner, um so seine Auslastung zu maximieren. Die Aufgabe besteht darin, einen probabilistischen Online-Algorithmus mit vernünftigem worst-case Performance-Verhältnis zu finden. Wir geben die Antwort auf ein offenes Problem von Lipton und Tompkins, das das bestmögliche Verhältnis betrifft. Weiter verallgemeinern wir ihre Ergebnisse auf einm-Maschinen-Analogon. Schließlich wird eine Variante des Problems analysiert, in dem der Rechner mit einem Zwischenspeicher für einen Job versehen ist.
    Notes: Abstract We consider the problem of scheduling tasks requiring certain processing times on one machine so that the busy time of the machine is maximized. The problem is to find a probabilistic online algorithm with reasonable worst case performance ratio. We answer an open problem of Lipton and Tompkins concerning the best possible ratio that can be achieved. Furthermore, we extend their results to anm-machine analogue. Finally, a variant of the problem is analyzed, in which the machine is provided with a buffer to store one job.
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    Computing 56 (1996), S. 105-116 
    ISSN: 1436-5057
    Keywords: 65C10 ; 62M99 ; 62F03 ; Pseudo-random number generators ; statistical evaluation ; tests ; error of type II ; renewal process
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung In einem früheren Artikel, vgl. [7], hat die erste Autorin Bewertungsmethoden von Pseudozufallsgeneratoren entwickelt, die auf Ideen der Computer-Simulation basieren. Dabei werden die Pseudozufallszahlen des getesteten Generators zur Modellierung gewisser Verteilungen herangezogen. Diese kann man mit theoretischen Verteilungen oder mit Verteilungen, die mittels wohlbekannter kanonischer Generatoren modelliert werden, vergleichen. Obige Methode kann aber versagen, falls wesentlich verschiedene Generatoren die Simulationen ausführen, welche mit Hilfe unserer einfachen Tests nicht auseinandergehalten werden können. In diesem Artikel werden Typen von kritischen Verteilungen konstruiert, die geometrisch bzw. arithmetisch gennant werden und durch bestimmte Bedingungen dargestellt werden. Es wird darauf hingewiesen, wie die Teilintervall-Methode, welche von den in [7] eingeführten Tests hergeleitet wird, zur Aufdeckung der kritischen Verteilungstype angewendet werden kann. In zusätczlichen Bemerkungen werden noch weitere Anwendungsaspekte unserer Bewertungsmethode betrachtet.
    Notes: Abstract In an earlier paper, cf. [7], the first author developed methods for evaluation of pseudo-random number generators based on ideas of computer simulation. More precisely, pseudo-random numbers of the tested generator are used to model certain distributions which can be compared with theoretical ones or with distributions modeled by means of well-known canonical generators. But this method can fail if essentially different generators produce simulations that cannot be distinguished by means of simple statistical tests developed in [7]. In the present paper two critical types of distributions, named geometric and arthmetic, are constructed that illustrate the circumstances above. Also it is shown how the subinterval method derived from the tests in [7] can serve to detect the described critical types of distributions. Additional aspects of old and new methods are shortly discussed.
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    Computing 56 (1996), S. 117-139 
    ISSN: 1436-5057
    Keywords: 65N22 ; 65N50 ; Local defect correction ; fast adaptive composite grid method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Wir analysieren einen Spezialfall der lokalen Defektkorrektur-Methode (LDC) die in [4] eingeführt wurde. Wir beschränken uns auf Finite-Differenzen-Diskretisierungen elliptischer Randwertprobleme. Die lokale Defektkorrektur-Methode verwendet Diskretisierungen auf einem globalen uniformen groben Gitter und einem oder mehreren lokalen uniformen feinen Gittern zur Approximation der stetigen Lösung. Wir beweisen, daß diese LDC-Methode als iterative Methode zur Lösung einer zugehörigen Diskretisierung auf dem zusammengesetzten Gitter betrachtet werden kann. Dieses Resultat ermöglicht es, wichtige Eigenschaften der LDC-Methode zu erklären, z.B. in Bezug auf die Größenordnung des Diskretisierungsfehlers. Außerdem ermöglicht die Formulierung der LDC-Methode als iterativer Solver für ein gegebenes Problem auf dem zusammengesetzten Gitter den Beweis eines engen Zusammenhangs zwischen LDC und der “Fast adaptive grid (FAC)”-Methode aus [8–10].
    Notes: Abstract We analyze a special case of the Local Defect Correction (LDC) method introduced in [4]. We restrict ourselves to finite difference discretizations of elliptic boundary value problems. The LDC method uses the discretization on a uniform global coarse grid and on one or more uniform local fine grids for approximating the continuous solution. We prove that this LDC method can be seen as an iterative method for solving an underlying composite grid discretization. This result makes it possible to explain important properties of the LDC method, e.g. concerning the size of the discretization error. Furthermore, the formulation of LDC as an iterative solver for a given composite grid problem makes it possible to prove a close correspondence between LDC and the Fast Adaptive Composite grid (FAC) method from [8–10].
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    Computing 56 (1996), S. 165-172 
    ISSN: 1436-5057
    Keywords: 90B35 ; 90C27 ; Combinatorial problems ; bin packing ; online algorithm ; worst-case analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Wir analysieren den von Kinnersley und Langston [5] vorgeschlagenen FFH-Algorithmus. Wir zeigen, daß der FFH Algorithmus eine scharfe Worst-Case Schranke von 1.7 hat und beantworten damit eine Frage in [5]. Variable Bingrößen werden ebenfalls betrachtet.
    Notes: Abstract We investigate and analyze the FFH algorithm proposed by Kinnersley and Langston [5]. We prove that the tight worst-case performance bound of FFH algorithm is 1.7, thereby answering a question in [5]. The case that bin sizes can be chosen is also considered.
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    Computing 56 (1996), S. 237-258 
    ISSN: 1436-5057
    Keywords: 65N55 ; 65N30 ; 65N22 ; 65N38 ; 78A30 ; Nonlinear partial differential equations ; domain decomposition ; boundary element methods ; finite element methods ; coupling ; magnetic field calculations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung In der vorliegenden Arbeit wird ein effizienter paralleler Algorithmus zur Lösung linearer und nichtlinearer Außenraumprobleme, wie sie z.B. in der Magnetostatik auftreten, beschrieben. Er basiert auf der Kopplung der Finite Elemente Methode mit der Galerkin-Randelementmethode mit Hilfe von Gebietszerlegungstechniken über eine einheitliche Variationsformulierung. Auf diese Weise können z.B. Magnetfeldprobleme mit der Sommerfeldschen Abstrahlbedingung vollständig modelliert werden. Die durch die Galerkin-Randelementmethode entstehende nichtsymmetrische Matrix wird in eine symmetrische indefinite Matrix transformiert, um Bramble/Pasciak's CG-Verfahren für indefinite Systeme anzuwenden. Zur Vorkonditionierung werden die neuesten Resultate auf dem Gebiet der Gebietszerlegungsmethoden genutzt. Numerische Resultate, die für zwei praktisch interessante Probleme, darunter ein nichtlineares, auf einem Mehrprozessorsystem erhalten wurden, werden diskutiert.
    Notes: Abstract An efficient parallel algorithm for solving linear and nonlinear exterior boundary value problems arising, e.g., in magnetostatics is presented. It is based upon the domaindecomposition-(DD)-coupling of Finite Element and Galerkin Boundary Element Methods which results in a unified variational formulation. In this way, e.g., magnetic field problems in an unbounded domain with Sommerfeld's radiation condition can be modelled correctly. The problem of a nonsymmetric system matrix due to Galerkin-BEM is overcome by transforming it into a symmetric but indefinite matrix and applying Bramble/Pasciak's CG for indefinite systems. For preconditioning, the main ideas of recent DD research are being applied. Test computations on a multiprocessor system were performed for two problems of practical interest including a nonlinear example.
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    Computing 56 (1996), S. 303-322 
    ISSN: 1436-5057
    Keywords: 65N20 ; 65N30 ; 65N55 ; Multigrid ; elliptic problems ; anisotropy ; convection-dominated
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Wir betrachten eine Zweigittermethode, die auf der Approximation des Schurkomplements basiert. Wir untersuchen die Abhängigkeit der Zweigitter-Konvergenzrate von bestimmten Parametern des Problems. Als Testprobleme wählen wir die rotierte anisotrope Diffusionsgleichung und die Konvektions-Diffusions-Gleichung. Mittels Fourieranalyse zeigen wir, daß die Zweigittermethode robust bezüglich Variationen in den relevanten Parametern des Problems ist. Als Mehrgittermethode verwenden wir einen üblichenW-Zyklus auf groben Gittern. Diese Mehrgittermethode hat dann dieselbe algorithmische Struktur wie eine Standard-Mehrgittermethode und ist effizient. Weiters erhalten wir bei Anwendung auf die zwei Testprobleme ebenso wie für die Zweigittermethode starke Robustheit bezüglich Variation der Problemparameter.
    Notes: Abstract We consider a two-grid method based on approximation of the Schur complement. We study the dependence of the two-grid convergence rate on certain problem parameters. As test problems we take the rotated anisotropic diffusion equation and the convection-diffusion equation. Using Fourier analysis we show that for both test problems the two-grid method is robust w.r.t. variation in the relevant problem parameters. For the multigrid method we use a standardW-cycle on coarse grids. This multigrid method then has the same algorithmic structure as a standard multigrid method and is fairly efficient. Moreover, when applied to the two test problems then, as in the two-grid method, we have a strong robustness w.r.t. variation of the problem parameters.
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    Computing 56 (1996), S. 259-301 
    ISSN: 1436-5057
    Keywords: 15A12 ; 35Q30 ; 65N30 ; 41A17 ; 41A63 ; Saddle point problems ; LBB condition ; multiresolution analysis ; wavelets ; time dependent problems ; Schur complements ; preconditioning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung In dieser Arbeit werden Galerkin-Verfahren für das Stokes-Problem untersucht, die auf speziell angepaßten Multiresolution-Ansätzen beruhen. Insbesondere wird gezeigt, daß gewisse Konstruktionsprinzipien für Wavelets auf gleichförmigen Gittern für jede Raumdimension und beliebige gewünschte Exaktheitsordnung auf Parre von Ansatzräumen führen, die die Ladyšenskaja-Babuška-Brezzi-Bedingung erfüllen. Darüber hinaus ergeben sich auch im instationären Fall aus den entsprechenden stabilen Multiskalenzerlegungen effiziente Vorkonditionierer für die Schurkomplemente entsprechenden systemmatrizen. Die Ergebnisse werden anhand einiger konkreter Realisierungen und numerischer Tests illustriert.
    Notes: Abstract The purpose of this paper is to investigate Galerkin schemes for the Stokes equations based on a suitably adapted multiresolution analysis. In particular, it will be shown that techniques developed in connection with shift-invariant refinable spaces give rise to trial spaces of any desired degree of accuracy satisfying the Ladyšenskaja-Babuška-Brezzi condition for any spatial dimension. Moreover, in the time dependent case efficient preconditioners for the Schur complements of the discrete systems of equations can be based on corresponding stable multiscale decompositions. The results are illustrated by some concrete examples of adapted wavelets and corresponding numerical experiments.
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    Computing 56 (1996), S. 323-341 
    ISSN: 1436-5057
    Keywords: 65D05 ; 65D07 ; 65D10 ; Piece wise Hermite interpolation ; shape preserving
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Ein lokaler Ansatz zur stückweisenC 1-Hermite-Interpolation wird vorgestellt. Die Interpolierende besteht aus zusammengesetzten kubischen und quadratischen Segmenten; sie erhält die Monotonie und/oder die Konvexität der Daten. Unter geeigneten Voraussetzungen approximier sie von vierter Ordnung.
    Notes: Abstract A local scheme for piecewiseC 1-Hermite interpolation is presented. The interpolant is obtained patching together cubic with quadratic polynomial segments; it is co-monotone and/or co-convex with the data. Under appropriate assumptions the method is fourth-order accurate.
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    Computing 56 (1996), S. 371-383 
    ISSN: 1436-5057
    Keywords: 65M10 ; Stability ; MacCormack scheme ; advection equation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Wir betrachten die zweidimensionale skalare Advektionsgleichung $$\frac{{\partial u}}{{\partial t}} = \hat a\frac{{\partial u}}{{\partial x}} + \hat b\frac{{\partial u}}{{\partial y}}$$ und zeigen, daß der Stabilitätsbereich des MacCormack-Schemasgenau durch $$\left( {\hat a\frac{{\Delta _t }}{{\Delta _x }}} \right)^{2/3} + \left( {\hat b\frac{{\Delta _t }}{{\Delta _x }}} \right)^{2/3} \leqslant 1$$ gegeben ist, wo Δ t , Δ x and δ y die Gitterabstände sind. Interessanterweise ist dieser Stabilitätsbereich identisch mit dem von Turkel für das Lax-Wendroff-Schema bestimmten Stabilitätsbereich.
    Notes: Abstract Let the two dimensional scalar advection equation be given by $$\frac{{\partial u}}{{\partial t}} = \hat a\frac{{\partial u}}{{\partial x}} + \hat b\frac{{\partial u}}{{\partial y}}.$$ We prove that the stability region of the MacCormack scheme for this equation isexactly given by $$\left( {\hat a\frac{{\Delta _t }}{{\Delta _x }}} \right)^{2/3} + \left( {\hat b\frac{{\Delta _t }}{{\Delta _x }}} \right)^{2/3} \leqslant 1$$ where Δ t , Δ x and Δ y are the grid distances. It is interesting to note that the stability region is identical to the one for Lax-Wendroff scheme proved by Turkel.
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    Computing 56 (1996), S. 385-395 
    ISSN: 1436-5057
    Keywords: 65F05 ; 15A23 ; nCUBE/2E multiprocessors ; matrix perturbation ; parallel algorithm ; performance ; ring network ; tridiagonal Toeplitz linear systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Wir betrachten die Lösung einer Klasse von speziellen tridiagonalen Gleichungssystemen, die schiefsymmetrische und Töplitz-Systeme einschließt, und geben einen schnellen, parallelen, Algorithmus dafür an. Bei Vorliegen von Diagonal-Dominanz benötigt unser paralleler Solver nur Kommunikation zwischen benachbarten Prozessoren auf einem Ring-Netzwerk. Eine Fehleranalyse wird angegeben. Einige experimentelle Resultate, die auf einem nCUBE/2E Gerät gewonnen wurden, zeigen das gute Verhalten unseres stabilen, parallelen Solvers.
    Notes: Abstract The solution of special linear, circulant-tridiagonal systems is considered. In this paper, a fast parallel algorithm for solving the special tridiagonal systems, which includes the skew-symmetric and tridiagonal-Toeplitz systems, is presented. Employing the diagonally dominant property, our parallel solver does need only local communications between adjacent processors on a ring network. An error analysis is also given. On the nCUBE/2E multiprocessors, some experimental results demonstrate the good performance of our stable parallel solver.
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    AI & society 10 (1996), S. 107-108 
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    AI & society 10 (1996), S. 109-126 
    ISSN: 1435-5655
    Keywords: Humann-centredness ; Human-machine symbiosis ; Information society ; Social innovation ; Rule-following ; Causality ; Human-purpose ; Subsidiarity ; Communitarianism ; Diversity
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    Topics: Computer Science
    Notes: Abstract The cornerstone of the British human-centred tradition lies in the two notions, human machine symbiosis and socially useful technology. The contemporary tradition has its roots in the LUCAS PLAN of the 1970s and has recently been shaped by a number of European social and technological movements in Scandianvia, Germany, France, Ireland and Italy. The emergence of the information society places the human-centred debate in wider socio-economic and cultural contexts. The paper explores the shaping of the European dimension of the human-centred tradition and proposes a research agenda for social innovation for inclusive information society.
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    AI & society 10 (1996), S. 219-225 
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    AI & society 10 (1996), S. 199-217 
    ISSN: 1435-5655
    Keywords: Design ; Design science ; Human-centred systems ; Social shaping of technology ; Design education
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    Topics: Computer Science
    Notes: Abstract Design of information systems, on the one hand, is often dominated by pure technical considerations of performance, correctness or reliability. On the other hand, sociological analysis of the social impact of information technology is not transfered to operationalised design criteria and to practice. The paper discusses this contradiction and tries to overcome the gap between computer science and social sciences in design by analysing the history of design in architecture and fine arts as well as the approaches of contemporary design-oriented disciplines. Based on this analysis and on the broad discussion about human-centredness, foundations of a new Design Science are outlined. Consequences for the education of computer scientists and software designers are discussed.
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    AI & society 10 (1996), S. 259-272 
    ISSN: 1435-5655
    Keywords: Body movement ; Intellectual disability ; Verbo-tonal system ; Vibrotactile stimulation
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    Topics: Computer Science
    Notes: Abstract Although this study does not directly prove the effects of vibrotactile stimulation and body movements, it does try to exhibit some observable effects on production of connected speech among three intellectually disabled subjects. Analysis of the subjects' utterances seems to show a certain improvement in prosodic features such as rhythmic structures and Fo (fundamental frequency) movement. On the other hand, segmental features like articulation of vowels and consonants remained relatively unchanged.
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    AI & society 10 (1996), S. 273-288 
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    Keywords: Cognitive ability ; Cognitive prosthetics ; Planning processes ; Pragmatics ; Relevance
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    Notes: Abstract Do AI programs just make it quicker and easier for humans to do what they can do already, or can the range of do-able things be extended? This paper suggests that cognitively-oriented technology can make it possible for humans to construct and carry out mental operations, which were previously impossible. Probable constraints upon possible human mental operations are identified and the impact of cognitive technology upon them is evaluated. It is argued that information technology functions as a cognitive prosthetic enhancing human intelligence and planning capabilities. Boundaries and constraints which Kant, Whorf, and many post-modernist theorists have seen as intrinsic to human cognition now cease to apply.
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    AI & society 10 (1996), S. 309-314 
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    Notes: Abstract This paper considers the potentially important role played by non-verbal communication in constraining pragmatic processing. Attention is paid to claims about the role of emotion in memory encoding and recall, its role in the formulation of plans and goals, and the creation of a shared emotional sense through various interpersonal processes. It is argued that ignoring these factors can lead to pragmatic theories which overestimate the processing demands facing the conversationalist, and that this overestimation will be problematic for any systems which seek to build on these theories in the future.
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    AI & society 10 (1996), S. 315-332 
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    Keywords: Communication ; Design ; Dialogism ; Human-Computer Interaction ; Pragmatics ; Reference
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    Topics: Computer Science
    Notes: Abstract Erroneously attributing propositional attitudes (desires, beliefs...) to computational artefacts has become internationally commonplace in the public arena, especially amongst the new generation of non-initiated users. Technology for rendering machines “user-friendly” is often inspired by interpersonal human communication. This calls forth designers to conceptualise a major component of human intelligence: the sense ofcommunicability, and its logical consequences. The inherentincommunicability of machines subsequently causes a shift in design strategy. Though cataloguing components of bouts between person and machine with Speech Act Theory has been popular, I will endeavour to present thesine qua non for their insertion into a larger unit of discourse — their societal embodiment. I shall argue that the so-called “intelligence” of the artificial should to be seenas a purposeful act that is socially generated, because it comes of Man,for Man. Designership will provide the forum for evolving user requirements and interface renewal.
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    AI & society 13 (1999), S. 1-3 
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    AI & society 13 (1999), S. 44-51 
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    Keywords: Assessment ; Ethics ; Prognosis ; Research and development ; Side effects
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    Notes: Abstract As societies become increasingly technologised, the need for careful and critical assessment rises. However, attempts to assess or normatively evaluate technological development invariably meet with an antinomy: both structurally and historically, technologies display multistable possibilities regarding uses, effects, side effects and other outcomes. Philosophers, usually expected to play applied ethics roles, often come to the scene after these effects are known. But others who participate at the research and development stages find even more difficulties with prognosis. Recent work on ‘revenge’ effects (Tenner) and negative side effects (Kevles) are examined, as well as several cases of philosophers in ‘R&D’ roles. After sketching the antinomy,I outline a heuristic pragmatics of prognosis that addresses this quandary.
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    AI & society 13 (1999), S. 63-68 
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    Keywords: Expert ; Japan ; Megascience ; Non-expert ; SSC
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    Notes: Abstract This article explores the relationship between experts and non-experts by examining of the SSC issue. The SSC, or Superconducting Supers Collider, was a large particle accelerator proposed in the early 1980s in the USA and cancelled in 1993. The SSC is generally talked about as a quintessential big science or megascience project. These big science projects inevitably need to be supported not only by government and industries but also by researchers who belong to other research fields or disciplines. High-energy physicists are experts within high-energy physics, but they are non-experts in other disciplines. The Japanese decision-making process of the SSC project clearly represents these interactions between experts and non-experts.
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    AI & society 13 (1999), S. 107-123 
    ISSN: 1435-5655
    Keywords: Globalisation ; Gender ; Place ; Industrialisation ; Malaysia
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    Notes: Abstract Current processes linking different parts of the world together economically and culturally are referred to asglobalisation. Though this term has gained immense popularity within a short time, critics have argued that it is hard to find empirical evidence that the world is becoming ‘one’. A crucial question is thenhow to look for such evidence. In many studies of globalisation, the general view taken is that of ‘global’, meaning that one searches for a global overview, or outlook, which is situated at no specific place. The present paper argues for a shift of focus, reasoning that to understand what is global we have to start with the local. The experiences of the global take place in particular local places, and to study such processes of change we need to situate our study in such a way that we can study the relationships between the local and the global. The particular place where our study takes place is rural Malaysia. Changes related to industrialisation are often spoken of in rather deterministic terms, in the sense that the local population are ‘victims’ of a global shift, whereas we argue for an alternative approach, analysing women workers as agents of change within their local community. Globalisation also mainly refers to external forces imposed on local actors, whereas we find the local to be imperative for the strategies of industrialists, as well as for the present processes of change.
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    AI & society 13 (1999), S. 135-155 
    ISSN: 1435-5655
    Keywords: Artificial markets ; Augmented capitalism ; Environment ; Technology
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    Notes: Abstract Notwithstanding the notion of progress, the social and environmental record of our age poses serious doubts for the present and the future. Technology, being the mainspring of progress, may be seen, accordingly, as the master of history more than the servant of society. In line with this view, a case can be made to strengthen the value of technology and to weaken the deterministic character of history. To do so, the paper canvasses the use of artificial markets designed to improve compliance of technology with environmental or social standards. The emerging interest in following this path poses a radical departure from the traditional policy approach to technology assessment. The traditional approach may be described asex ante, relying on cost-benefit analysis to anticipate the welfare effects of technology, combining this analysis with bureaucratic management based on command and control. Cost-benefit analysis, however, is piecemeal and shortsighted and, in a dynamic and synergistic world, can be considered of limited value to ensure longer-term goals. On the other hand, artificial markets operateex post and on the basis of ambient standards. As such, they constitute an artificial device that does not require discretion and a predictive capacity that social science cannot offer. Nonetheless, and given political will, this new approach offers the potential to ensure efficient and sustainable outcomes under conditions of uncertainty.
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    AI & society 13 (1999), S. 176-192 
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    Keywords: Computing professionals ; Conceptions of the future ; Culture of the computing field ; Visions of future technology
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    Notes: Abstract In this article we look at the conceptions computing professionals have of the future. We studied these conceptions by analysing 31 essays on the future published in theCommunications of the ACM. We found the future was envisioned from three different perspectives: in addition to a technology centred perspective the authors also used human centred and society centred perspectives, but region centred and organisation centred perspectives were missing. I assume the visions of these individuals of future technology represent the culture of the computing field as they are published in one of the top computer science journals.
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    AI & society 13 (1999), S. 210-213 
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    AI & society 13 (1999), S. 215-217 
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    AI & society 13 (1999), S. 247-262 
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    Keywords: China ; Development ; East Asia ; Globalisation ; Information and communication technology ; Science and technology policy
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    Notes: Abstract Science and technology development is increasingly driven by the requirements of a globalising world economy. Information and communication technologies both support this globalisation process, and provide opportunities to participate in it. However, the process of development is not uniform. Within nation states and within regions there is considerable inequity in the scale and pace of development. Successful science and technology policies require an understanding of location within a global production network and of local capabilities. This paper explores the prospects for such policies in the context of North East Asia.
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    AI & society 13 (1999), S. 218-234 
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    Keywords: Culture ; Knowledge transfer ; Mediation ; Negotiation ; Propositional knowledge ; Tacit knowledge
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    Topics: Computer Science
    Notes: Abstract In man-machine communication, there is a relationship between what may be described as tacit (human) and explicit (machine) knowledge. The tacit lies in practice and the explicit in the formulation of the processes and content of this practice. However, when a human communicates with another human face to face, we may describe them as communicating aspects of the tacit and explicit dimension of their knowledge, i.e. the expression and its background of meaning for the particular situation. When this is unsuccessful in being communicated, some mediator (not necessarily a third person) is needed to provide the bridge for the particular discrepant aspects of the tacit and explicit dimensions to meet. This is achieved by making the tacit nature of the discrepancy in the communication explicit to both participants such that they both understand the background to their discrepancy. Once they become aware, it is possible for them to begin to resolve it. In considering what has been termed here the ‘cultural interface’, i.e. communication across cultures, the paper will explore the nature of discrepancies in communication and the means by which we can accommodate to each other's differences, either via third party help or between ourselves. The interaction of each person's tacit (background of practices) and their interpretation, set against this background, of the explicit (the utterance, silence, gesture) needs to find some mutual ground, involving their cultural self. The operation of mediation and negotiation will be considered in this context.
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    AI & society 13 (1999), S. 322-328 
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    AI & society 13 (1999), S. 329-340 
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    AI & society 13 (1999), S. 312-321 
    ISSN: 1435-5655
    Keywords: Artificial intelligence ; Free time ; Human-centred education ; Human-machine boundary ; Human nature ; Work
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract This paper considers the impact of the AI R&D programme on human society and the individual human being on the assumption that a full realisation of the engineering objective of AI, namely, construction of human-level, domain-independent intelligent entities, is possible. Our assumption is essentially identical tothe maximum progress scenario of the Office of Technology Assessment, US Congress. Specifically, the first section introduces some of the significant issues on the relational nexus among work, education and the human-machine boundary. In particular, based on a Russellian conception of rationality I briefly argue that we need to change our related conceptions of work, employment and free time, through a new human-centred education. On the human-machine boundary problem, I make a couple of tentative suggestions and put forward some crucial open questions. Section two discusses the impact of the emerging machine intelligence on human nature both as modification of its self-image, keeping human nature itself unchanged, and its potential for altering human nature itself. I briefly argue that: (i) in a certain context, the question of the supremacy or uniqueness of human intelligence loses much, if not all, of its ‘weight’; and (ii) appearance of Robot-X species would immortalise the human spirit.
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    AI & society 13 (1999), S. 357-376 
    ISSN: 1435-5655
    Keywords: Context ; CSCW ; Culture ; Design ; Interface ; Japan ; Work
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract The past decade has seen the development of a perspective holding that technology is socially constructed. This paper examines the social construction of one group of technologies: systems for computer-supported cooperative work (CSCW). It describes the design of CSCW in Japan, with particular attention to the influence of culture on the design process. Two case studies are presented to illustrate the argument that culture is an important factor in technology design, despite commonly held assumptions about the neutrality and objectivity of science and technology. The paper further argues that, by looking at CSCW systems as texts which reflect the context of their production and the society from which they come, we may be better able to understand the transformations that operate when these texts are ‘read’ in the contexts of their implementation.
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    AI & society 13 (1999), S. 377-388 
    ISSN: 1435-5655
    Keywords: Communication ; Culture ; Ethics ; Indigenous ; Information systems ; Participative development ; Postcolonial ; Postmodern
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract This article discusses ways to operationalise the concept of culturally appropriate computer-mediated communication, utilising information systems (IS) development methodologies and adopting a postmodern and postcolonial perspective. By way of illustration, it describes progress on the participative development of the Ieramugadu Cultural Information System. This project is designed to develop and evaluate innovative procedures for elicitation, analysis, storage and communication of indigenous cultural heritage information. It is investigating culturally appropriate IS design techniques, multimedia approaches and ways to ensure protection of secret/sacred information. Ethical issues are foregrounded.
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    AI & society 13 (1999), S. 435-445 
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    AI & society 13 (1999), S. 421-434 
    ISSN: 1435-5655
    Keywords: Deconstruction ; Internet theory ; Jacques Derrida ; Media philosophy ; Philosophy of time ; Pragmatism ; Richard Rorty ; Transcultural communication ; Virtual communities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract My considerations are organised into four sections. The first section provides a survey of some significant developments that determine contemporary philosophical discussion on the subject of ‘time’. In the second section, I show how the question of time and the issue of media are linked with one another in the views of two influential contemporary philosophers: Jacques Derrida and Richard Rorty. Finally, in the third section, the temporal implications of cultural practices which are developing in the new medium of the Internet are analysed and, in the fourth section, related to the central theses of Derrida and Rorty.
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    AI & society 13 (1999), S. 402-420 
    ISSN: 1435-5655
    Keywords: Computers ; Constructivism ; Cultural ; Education ; Interpretation ; Social ; Technology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract The Social Construction of Technology (SCOT) theory offers a useful conceptual framework for examining the social and cultural factors that may contribute to or detract from the successful integration of computer technology into educational environments. This theory, which grew out of studies in the history of technology and the sociology of science, suggests methods for studying the phenomenon of technological development, such as identifying the relevant social groups involved in the development process and the factors that either leave the technology in a state of interpretive flexibility or bring the interpretation of the technology to closure. This paper uses a SCOT approach to explore how personal and institutional beliefs can shape the ways in which technologies are used by teachers and students, and to identify the social, epistemological, cognitive and motivational factors that need to be considered as computer technology becomes an integral part of the educational experience.
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    AI & society 10 (1996), S. 164-180 
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    Keywords: Human-centredness ; Scandinavian school ; Computer theory ; Research paradigms ; Complexity ; Communication ; Interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Currently there is a clear trend towards questioning the traditional sovereign human self which for two hundred years has had an undisputed central status within European culture and philosophy. This challenges the tradition of anthropocentrism which in a Scandinavian computer science context has had two theoretical foundations: the workoriented design theory represented by the Scandinavian participatory design philosophy, and the idea of the computer to a rather passive medium for human communication. The process, reducing the computer to a rather passive medium for human communication. The paper firstly examines these two theoretical anthropocentric positions. Secondly it outlines the trend towards challenging the status of the human self within different research contexts. This trend represents a challenge for Human-centred systems design. Finally, it discusses the new demands for conceptualising basic IT research phenomena created by this development, with particular focus on the issue of human-centredness as a systems design strategy.
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    AI & society 10 (1996), S. 181-198 
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    Keywords: Human-centred ; Information society ; Social cohesion ; Tripartite collaboration ; Democratic participation ; Community telecottages ; Community Teleservice Centres (CTSC)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract The paper argues that the human-centred approach should be considered as an alternative to the techno-economic model of the EC information society. This alternative approach should be based on the principles of democratic participation of citizens and social cohesion. Using a community development based approach the paper introduces concepts of partnership, tripartite collaboration and universal participation. Having evaluated a human-centred approach to the information society this is then applied to the results of four case studies of Danish and Swedish community teleservice centres (CTSCs), and the subsequent lessons drawn.
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    AI & society 13 (1999), S. 156-163 
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    Keywords: Scientific rationality ; SSK ; Strong programme
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    Topics: Computer Science
    Notes: Abstract This is a programmatic proposal about a better use of the notion ofscientific rationality in the sociology of scientific knowledge (SSK). Strangely enough, some relativistic authors in the SSK literature allow room for scientific rationality in their analyses of scientific practice. I interpret their arguments as follows: since science is essentially a collective activity, any rationality developed and sustained in science should have someinstitutional basis analysable in sociological terms. I advocate that sociologists should explain such scientific rationality, especially the asymmetry between science and nonscience, in sociological terms. In some sense, my programme is ‘even stronger’ than Bloor's ‘strong programme’.
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    AI & society 13 (1999), S. 193-199 
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    AI & society 13 (1999), S. 164-175 
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    Keywords: Environmental conditions ; Fundamental human needs ; Humanistic nature of technology ; Nursing theory ; People's health and welfare ; Promotion of adaptation
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    Topics: Computer Science
    Notes: Abstract The current viewpoint on technology seems to derive from the optimistic idea of the existence of pre-established harmony that any technological progress leads to people's health, and welfare. But history has shown us that this is not always the case, and that we must select the proper direction which leads to health and welfare. For that purpose, this article presents the viewpoint of technology as a kind of human care service, along with the lessons from nursing theories. Five leading nursing theories are introduced as well as their implications for technology. ‘The nursing model of technology’ is then presented.
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    AI & society 13 (1999), S. 200-209 
    ISSN: 1435-5655
    Keywords: Network organisation ; Virtual office ; Virtual organisation ; Virtual team ; Web enterprise
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    Topics: Computer Science
    Notes: Abstract This paper deals with the different meanings given to the concept of virtual organisation. A typology developed by Campbell, consisting of four forms of virtual organisation, is presented. We illustrate this categorisation with practical examples. We will explain why we use the term virtual organising rather than virtual organisation. Our conclusion is that organisations planning to go virtual have to make technological and organisational decisions that are intertwined at a strategic level, resulting in a specific sociotechnical configuration of virtual organising.
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    AI & society 13 (1999), S. 235-246 
    ISSN: 1435-5655
    Keywords: Business media ; China and Japan ; Economic and technological change ; Metaphors ; Stereotypes
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    Topics: Computer Science
    Notes: Abstract In this paper some aspects of the stereotyping of China and Japan are explored by using a sample of articles from a Swedish business magazine. The main objective is to show how stereotypes are adapted to capture new developments in economy and technology. During the years of high hopes for the largest Asian economies, stereotypes proved to be far from timeless and unchanging. Also a large number of metaphors were used to express perceived similarities between East and West, further undermining tradi-tional Western understanding of Asia as inert and eternally different. The recent decline of Japan put an end to this, creating a return to a vocabulary of cultural characterisations and explanations.
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    Keywords: East Asia ; Knowledge ; Phenomenological approach ; Social relationship ; Structural approach ; Technology
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    Notes: Abstract The objective of this work is to analyse technology and social relationships using the concept of knowledge. Therefore technology is not only a means to produce and social relationships a means to interact, but also the result of a whole of elements. The concept of knowledge aims to analyse these elements both from a structural point of view, highlighting their characteristics, and from a dynamic point of view, which considers how subjects interpret and make sense of them. In this framework technologies and social relationships are reinterpreted according to knowledge that characterises each context, suggesting some clues to design technologies, information technologies and social policies.
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    AI & society 13 (1999), S. 301-311 
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    AI & society 13 (1999), S. 282-300 
    ISSN: 1435-5655
    Keywords: China ; Competition ; Computerisation ; Culture ; Identity ; Japan ; Metaphor ; Mobile phone ; Nordic countries ; Trust
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    Topics: Computer Science
    Notes: Abstract This article is based on the writer's participant observations of multidisciplinary Nordic-Japanese discussions in August 1997 and October 1998 concerning the cultural acceptance of the new information and communication technologies (NICT) in Japan, China and the Nordic countries. Concepts and theoretical ideas from the sociology of technology and science are applied. The main question is how to frame sociologically a study on the local differences in attitudes toward and the adoption of NICT. The main results are: (1) NICT products are carriers of metaphoric meanings of society and the individual; (2) the image of the information society attached to the computer is less attractive than the metaphoric contents carried by the mobile phone; (3) the mobile phone is more persuasively independent from cultural differences, because of its independence from the cultural differences, the mobile phone is more attractive to the majority of consumers. Its metaphoric reference unlike the computers, is non-verbal and therefore unanalysable and for the same reason also more capable of being freely constructed locally and individually.
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    Engineering with computers 12 (1996), S. 46-61 
    ISSN: 1435-5663
    Keywords: Active structural control ; Calculus of communicating systems (CCS) ; Concurrency workbench ; Modechart ; Real-time systems ; Simulation ; Temporal CCS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract In this paper we describe complementary approaches that can be used to ensure the reliability of real-time systems, such as those used in active structural control systems. These approaches include both model-checking and simulation, and are based on a temporal process algebra. We combine these formal methods with a high-level, graphical modeling technique, Modechart, to specify an active structural control system consisting of several processors. Timing requirements on the system are specified and verified with a combination of process algebraic models and modal logic, and various simulation concepts are described for debugging models and for gaining insight into system behavior.
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    Keywords: Adaptive mesh refinement ; Finite element method ; Mesh generation
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    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Use of quadrilateral elements for finite element mesh refinement can lead either to so-called ‘irregular’ meshes or the necessity of adjustments between finer and coarser parts of the mesh necessary. In the case of ‘irregular’ meshes, constraints have to be introduced in order to maintain continuity of the displacements. Introduction of finite elements based on blending function interpolation shape functions using piecewise boundary interpolation avoids these problems. This paper introduces an adaptive refinement procedure for these types of elements. The refinement is anh-method. Error estimation is performed using the Zienkiewicz-Zhu method. The refinement is controlled by a switching function representation. The method is applied to the plane stress problem. Numerical examples are given to show the efficiency of the methodology.
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    Engineering with computers 12 (1996), S. 94-106 
    ISSN: 1435-5663
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract This paper discusses the development of an automatic mesh generation technique designed to operate effectively on multiple instruction multiple data (MIMD) parallel computers. The meshing approach is hierarchical, that is, model entities are meshed after their boundaries have been meshed. Focus is on the region meshing step. An octree is constructed to serve as a localization tool and for efficiency. The tree is also key to the efficient parallelization of the meshing process since it supports the distribution of load to processors. The parallel mesh generation procedure repartitions the domain to be meshed and applies on processor face removals until all face removals with local data have been performed. The portion of the domain to be meshed remaining is dynamically repartitioned at the octant level using an Inertial Recursive Bisection method and local face removals are reperformed. Migration of a terminal octant involves migration of the octant data and the octant's mesh faces and/or mesh regions. Results show relatively good speed-ups for parallel face removals on small numbers of processors. Once the three-dimensional mesh has been generated, mesh regions may be scattered across processors. Therefore, a final dynamic repartitioning step is applied at the region level to produce a partition ready for finite element analysis.
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    Engineering with computers 12 (1996), S. 120-141 
    ISSN: 1435-5663
    Keywords: Discontinuous Galerkin ; Error estimation adaptivity ; Postprocessing ; Superconvergence
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    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The paper discusses error estimation and h-adaptive finite element procedures for elasticity and plasticity problems. For the spatial discretization error, an enhanced Superconvergent Patch Recovery (SPR) technique which improves the error estimation by including fulfillment of equilibrium and boundary conditions in the smoothing procedure is discussed. It is known that an accurate error estimation on an early stage of analysis results in a more rapid and optimal adaptive process. It is shown that node patches and element patches give similar quality of the postprocessed solution. For dynamic problems, a postprocessed type of error estimate and an adaptive procedure for the semidiscrete finite element method are discussed. It is shown that the procedure is able to update the spatial mesh and the time step size so that both spatial and time discretization errors are controlled within specified tolerances. A time-discontinuous Galerkin method for solving the second-order ordinary differential equations in structural dynamics is also presented. Many advantages of the new approach such as high order accuracy, possibility to filter effects of spurious modes and convenience to apply adaptive analysis are observed. For plasticity problems, some recent work that improved plastic strains and plastic localization is discussed.
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    Engineering with computers 12 (1996), S. 144-154 
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    Keywords: Automatic mesh generation ; Mesh control ; Mapped meshing
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    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract This paper presents generated enhancements for robust ‘two and three-quarter dimensional meshing’, including: (1) automated interval assignment by integer programming for submapped surfaces and volumes, (2) surface submapping, and (3) volume submapping. An introduction to the simplex method, an optimization technique of integer programming, is presented. Simplification of complex geometry is required for the formulation of the integer programming problem. A method of ‘i-j unfolding’ is defined which explains how irregular geometry can be realigned into a simplified form that is suitable for submap interval assignment solutions. Also presented is the processes by which submapping eliminates the decomposition of surface geometry, through a pseudodecomposition process, producing suitable mapped meshes. The process of submapping involves the creation of ‘interpolated virtual edges’, user defined ‘vertex types’ and ‘i-j-k space’ traversals. The creation of ‘interpolated virtual edges’ is the method by which submapping automatically subdivides surface geometry. The ‘interpolated virtual edge’ is formulated according to an interpolation scheme using the node discretization of curves on the surface. User defined ‘vertex types’ allow direct user control of surface decomposition and interval assignment by modifying ‘i-j-k space’ traversals. Volume submapping takes the geometry decomposition to a higher level by using ‘mapped virtual surfaces’ to eliminate decomposition of complex volumes.
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    Engineering with computers 12 (1996), S. 178-185 
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    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract HEXAR, a new software product developed at Cray Research, Inc., automatically generates good quality meshes directly from surface data produced by computeraided design (CAD) packages. The HEXAR automatic mesh generator is based on a proprietary and parallel algorithm that relies on pattern recognition, local mesh refinement and coarsening, and variational mesh smoothing techniques to create all-hexahedral volume meshes. HEXAR generates grids two to three orders of magnitude faster than current manual approaches. Although approximate by design, the resulting meshes have qualities acceptable by many commercial structural and CFD (computational fluid dynamics) software. HEXAR turns mesh generation into an automatic process for most commercial engineering applications.
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    Engineering with computers 12 (1996), S. 186-210 
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    Keywords: Finite elements ; Grid generation ; Tetrahedra ; Unstructured grids
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    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract We describe recent extensions and improvements to the advancing front grid generation technique. These improvements target a range of applicability, speed and user friendliness. The range of applicability is enlarged by the ability to produce volumetric grids around thin surfaces (such as shells, membranes, fabrics or surfaces with cusps), the generation of high aspect ratio grids for Navier-Stokes applications, the generation of higher order triangular and tetrahedral elements, and the generation of quadrilateral and hexahedral elements. Speed improvements are the result of reduced search overheads, as well as vectorization and parallelization. User friendliness is enhanced by the ability to grid directly discrete data and simpler ways of specifying the desired element size and shape in space. Numerous examples are included that demonstrate the versatility and maturity that advancing front grid generators have achieved.
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    Mathematical programming 84 (1999), S. 137-160 
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    Keywords: Key words: convex inequalities – global error bound – asymptotic constraint qualification – bounded excess condition
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    Keywords: Key words: nonlinear programming – successive quadratic programming – trust regions – augmented Lagrangians – Lipschitz conditions
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    Notes: The strategy for obtaining global convergence is based on the trust region approach. The merit function is a type of augmented Lagrangian. A new updating scheme is introduced for the penalty parameter, by means of which monotone increase is not necessary. Global convergence results are proved and numerical experiments are presented.
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    Mathematical programming 84 (1999), S. 219-226 
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    Keywords: Key words: quadratic programming – global maximizer – approximation algorithm ; Mathematics Subject Classification (1991): 90C20, 90C26, 90C27
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    Mathematical programming 84 (1999), S. 421-434 
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    Keywords: Key words: Legendre condition – second-order optimality condition – envelope – inequality state constraint – weak minimal solution
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    Notes: , they differ from the Legendre-Clebsch condition. They give information about the Hesse matrix of the integrand at not only inactive points but also active points. On the other hand, since the inequality state constraints can be regarded as an infinite number of inequality constraints, they sometimes form an envelope. According to a general theory [9], one has to take the envelope into consideration when one consider second-order necessary optimality conditions for an abstract optimization problem with a generalized inequality constraint. However, we show that we do not need to take it into account when we consider Legendre-type conditions. Finally, we show that any inequality state constraint forms envelopes except two trivial cases. We prove it by presenting an envelope in a visible form.
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    Mathematical programming 84 (1999), S. 283-312 
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    Keywords: Key words: statistical disclosure control – cell suppression – branch-and-cut ; Mathematics Subject Classification (1991): 90C10, 90B10, 68R10
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    Mathematical programming 84 (1999), S. 375-399 
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    Keywords: Key words: monotone complementarity problem – homogeneous and self-dual – infeasible-starting algorithm ; Mathematics Subject Classification (1991): 90C25, 90C33
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    Mathematical programming 84 (1999), S. 467-481 
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    Mathematical programming 84 (1999), S. 565-576 
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    Keywords: Mathematics Subject Classification (1991): 05C70, 90C27
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    Notes: In order to unify these approaches, here we describe a two-phase greedy algorithm working on a slight extension of lattice polyhedra. This framework includes the rooted node-connectivity augmentation problem, as well, and hence the resulting algorithm, when appropriately specialized, finds a minimum cost of new edges whose addition to a digraph increases its rooted connectivity by one. The only known algorithm for this problem used submodular flows. Actually, the specialized algorithm solves an extension of the rooted edge-connectivity and node-connectivity augmentation problem.
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    Mathematical programming 84 (1999), S. 595-640 
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    Keywords: Key words: graph augmentation – edge connectivity – hypergraphs – randomized algorithms – parallel algorithms – combinatorial optimization
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    Notes: 1 ,E2,..., such that ⋃i≤τEi optmially increases the connectivity by τ, for any integer τ. The main result of the paper is that this sequence of edge sets can be divided into O(n) groups such that within one group, all Ei are basically the same. Using this result, we improve on the running time of edge connectivity augmentation, as well as we give the first parallel (RNC) augmentation algorithm. We also present new efficient subroutines for finding the so-called extreme sets and the cactus representation of min-cuts required in our algorithms. Augmenting the connectivity of hypergraphs with ordinary edges is known to be structurally harder than that of ordinary graphs. In a weaker version when one exceptional hyperedge is allowed in the augmenting edge set, we derive similar results as for ordinary graphs.
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    Mathematical programming 85 (1999), S. 193-206 
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    Keywords: Key words: quadratic programming problem – Karush-Kuhn-Tucker point set – upper semicontinuity – lower semicontinuity –R0-matrix
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    Mathematical programming 85 (1999), S. 181-192 
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    Keywords: Key words: stability analysis – perturbation theory – degenerate optimization – error estimation – quadratic program stability – merit functions ; Mathematics Subject Classification (1991): 90C31, 90C30, 65G
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    Mathematical programming 86 (1999), S. 649-659 
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    Keywords: Key words: parametric optimization – singularities – jumps – regularity Mathematics Subject Classification (1991): 90C30, 90C31
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    Topics: Computer Science , Mathematics
    Notes: Abstract. The paper presents an interior embedding of nonlinear optimization problems. This embedding satisfies a sufficient condition for the success of pathfollowing algorithms with jumps being applied to one-parametric optimization problems.¶The one-parametric problem obtained by the embedding is supposed to be regular in the sense of Jongen, Jonker and Twilt. This asumption is analyzed, and its genericity is proved in the space of the original optimization problems.
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  • 90
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    Mathematical programming 85 (1999), S. 617-642 
    ISSN: 1436-4646
    Keywords: Key words: fixed-charge continuous knapsack problem – convex maximization – generalized fixed-cost function – greedy solution – pseudogreedy solution – sensitivity analysis
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  • 91
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    Mathematical programming 85 (1999), S. 397-406 
    ISSN: 1436-4646
    Keywords: Key words: parameterized nonlinear complementarity problems – solution stability – B-derivatives – Lipschitz continuity – local upper Lipschitz continuity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: n such that x≥0,  F(x,u)-v≥0 , and F(x,u)-v T·x=0 where these are vector inequalities. We characterize the local upper Lipschitz continuity of the (possibly set-valued) solution mapping which assigns solutions x to each parameter pair (v,u). We also characterize when this solution mapping is locally a single-valued Lipschitzian mapping (so solutions exist, are unique, and depend Lipschitz continuously on the parameters). These characterizations are automatically sufficient conditions for the more general (and usual) case where v=0. Finally, we study the differentiability properties of the solution mapping in both the single-valued and set-valued cases, in particular obtaining a new characterization of B-differentiability in the single-valued case, along with a formula for the B-derivative. Though these results cover a broad range of stability properties, they are all derived from similar fundamental principles of variational analysis.
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  • 92
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    Mathematical programming 85 (1999), S. 573-592 
    ISSN: 1436-4646
    Keywords: Key words: disjoint bilinear problem – linear maxmin problem – branch and bound algorithm – global optimization
    Source: Springer Online Journal Archives 1860-2000
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  • 93
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    Mathematical programming 85 (1999), S. 469-490 
    ISSN: 1436-4646
    Keywords: Key words: convex nondifferentiable minimization – projection method – acute cone – obtuse cone
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  • 94
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    Mathematical programming 86 (1999), S. 51-63 
    ISSN: 1436-4646
    Keywords: Key words: stochastic program – upper bound – recourse problem – Gaussian Mathematics Subject Classification (1991): Primary 90C15; secondary 90C05, 90C25, 90C35
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. We present a construction which gives deterministic upper bounds for stochastic programs in which the randomness appears on the right–hand–side and has a multivariate Gaussian distribution. Computation of these bounds requires the solution of only as many linear programs as the problem has variables.
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  • 95
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    Mathematical programming 86 (1999), S. 17-39 
    ISSN: 1436-4646
    Keywords: Key words: mixed-integer programming – branch-and-cut – computing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. We present a branch-and-cut algorithm to solve capacitated network design problems. Given a capacitated network and point-to-point traffic demands, the objective is to install more capacity on the edges of the network and route traffic simultaneously, so that the overall cost is minimized. We study a mixed-integer programming formulation of the problem and identify some new facet defining inequalities. These inequalities, together with other known combinatorial and mixed-integer rounding inequalities, are used as cutting planes. To choose the branching variable, we use a new rule called “knapsack branching”. We also report on our computational experience using real-life data.
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  • 96
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    Keywords: Key words: angle – asymptotic constraint qualification – basic constraint qualification – bounded linear regularity – CHIP – conical hull intersection property – convex feasibility problem – convex inequalities – constrained best approximation – error bound – Friedrichs angle – Hoffman’s error bound – linear inequalities – linear regularity – orthogonal projection – property (G) Mathematics Subject Classification (1991): Primary 90C25; Secondary 15A39, 41A29, 46A40, 46C05, 90C31
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. The strong conical hull intersection property and bounded linear regularity are properties of a collection of finitely many closed convex intersecting sets in Euclidean space. These fundamental notions occur in various branches of convex optimization (constrained approximation, convex feasibility problems, linear inequalities, for instance). It is shown that the standard constraint qualification from convex analysis implies bounded linear regularity, which in turn yields the strong conical hull intersection property. Jameson’s duality for two cones, which relates bounded linear regularity to property (G), is re-derived and refined. For polyhedral cones, a statement dual to Hoffman’s error bound result is obtained. A sharpening of a result on error bounds for convex inequalities by Auslender and Crouzeix is presented. Finally, for two subspaces, property (G) is quantified by the angle between the subspaces.
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  • 97
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    Mathematical programming 86 (1999), S. 187-197 
    ISSN: 1436-4646
    Keywords: Key words: quadratic forms – convex combination – matrix perturbation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. We extend an interesting theorem of Yuan [12] for two quadratic forms to three matrices. Let C 1, C 2, C 3 be three symmetric matrices in ℜ n×n , if max{x T C 1 x,x T C 2 x,x T C 3 x}≥0 for all x∈ℜ n , it is proved that there exist t i ≥0 (i=1,2,3) such that ∑ i=1 3 t i =1 and ∑ i=1 3 t i C i has at most one negative eigenvalue.
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  • 98
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    Mathematical programming 86 (1999), S. 367-386 
    ISSN: 1436-4646
    Keywords: Key words: variational inequality problem – D-gap function – Newton’s method – unconstrained optimization – global convergence – quadratic convergence ; Mathematics Subject Classification (1991): 90C99
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. The variational inequality problem (VIP) can be reformulated as an unconstrained minimization problem through the D-gap function. It is proved that the D-gap function has bounded level sets for the strongly monotone VIP. A hybrid Newton-type method is proposed for minimizing the D-gap function. Under some conditions, it is shown that the algorithm is globally convergent and locally quadratically convergent.
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  • 99
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    Mathematical programming 86 (1999), S. 433-438 
    ISSN: 1436-4646
    Keywords: Key words: variational inequalities – coercivity – pseudomonotonicity ; Mathematics Subject Classification (1991): 49J40
    Source: Springer Online Journal Archives 1860-2000
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  • 100
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    Mathematical programming 86 (1999), S. 283-312 
    ISSN: 1436-4646
    Keywords: Key words: convex programming – Lagrangean duality – Lagrangean relaxation – subgradient optimization – ergodic convergence – primal convergence – traffic equilibrium assignment – road pricing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. Lagrangean dualization and subgradient optimization techniques are frequently used within the field of computational optimization for finding approximate solutions to large, structured optimization problems. The dual subgradient scheme does not automatically produce primal feasible solutions; there is an abundance of techniques for computing such solutions (via penalty functions, tangential approximation schemes, or the solution of auxiliary primal programs), all of which require a fair amount of computational effort. We consider a subgradient optimization scheme applied to a Lagrangean dual formulation of a convex program, and construct, at minor cost, an ergodic sequence of subproblem solutions which converges to the primal solution set. Numerical experiments performed on a traffic equilibrium assignment problem under road pricing show that the computation of the ergodic sequence results in a considerable improvement in the quality of the primal solutions obtained, compared to those generated in the basic subgradient scheme.
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