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  • 2005-2009
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  • Articles  (6,585)
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  • 2005-2009
  • 1980-1984  (6,585)
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  • 1
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    Springer
    Mathematical programming 22 (1982), S. 71-81 
    ISSN: 1436-4646
    Keywords: Blocking ; Antiblocking ; Polarity ; Penumbra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract E. Johnson has recently shown that the concept of a penumbra leads to a simple geometric description of the blocker and antiblocker of a given set. Here we develop some basic results on penumbras which permit us to slightly generalize and simplify results on their relationship to blocking and antiblocking theory. In addition, motivated by the obvious symmetry of our results, we examine the effect of reversing the blocking and antiblocking operations.
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  • 2
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    Mathematical programming 22 (1982), S. 121-121 
    ISSN: 1436-4646
    Source: Springer Online Journal Archives 1860-2000
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  • 3
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    Mathematical programming 22 (1982), S. 148-162 
    ISSN: 1436-4646
    Keywords: Set Covering Problem ; Median Problem ; Location Problems ; Heuristics ; Worst Case Analysis ; Continuous Location Problem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract We describe in this paper polynomial heuristics for three important hard problems—the discrete fixed cost median problem (the plant location problem), the continuous fixed cost median problem in a Euclidean space, and the network fixed cost median problem with convex costs. The heuristics for all the three problems guarantee error ratios no worse than the logarithm of the number of customer points. The derivation of the heuristics is based on the presentation of all types of median problems discussed as a set covering problem.
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  • 4
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    Mathematical programming 22 (1982), S. 227-230 
    ISSN: 1436-4646
    Keywords: Minimax ; Nonconvex Optimization ; Stationary Points
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract We give a short proof that in a convex minimax optimization problem ink dimensions there exist a subset ofk + 1 functions such that a solution to the minimax problem with thosek + 1 functions is a solution to the minimax problem with all functions. We show that convexity is necessary, and prove a similar theorem for stationary points when the functions are not necessarily convex but the gradient exists for each function.
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  • 5
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    Mathematical programming 24 (1982), S. 257-268 
    ISSN: 1436-4646
    Keywords: Nondifferentiable Programming ; Convex Analysis ; Sensivity Analysis ; Duality Theory ; Second Order Derivative ; Second Order Methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract We study differential properties of the support function of the∈-subdifferential of a convex function; applications in algorithmics are also given.
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  • 6
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    Mathematical programming 22 (1982), S. 93-103 
    ISSN: 1436-4646
    Keywords: Linear Programming ; Relaxation Method ; Polynomiality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract A class of linear programs is given in which the relaxation method for inequalities, under the same operating rules as Khacian's method, is not polynomial in the length of the input. This result holds for any value of the relaxation parameter.
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  • 7
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    Mathematical programming 22 (1982), S. 117-120 
    ISSN: 1436-4646
    Keywords: Augmenting Path Algorithm ; Boolean Lattice ; Jordan-Hölder Theorem ; Matroid Intersection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract It is noted that the decomposition of a network presented by J.C. Picard and M. Queyranne through an algorithmic argument may be defined from a general lattice-theoretic result for more general problems for which the equalities of maximum-flow minimum-cut type hold.
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  • 8
    ISSN: 1436-4646
    Keywords: Geometric Programming ; Code Comparisons ; Numerical Testing ; Nonlinear Programming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract Ten codes or code variants were used to solve the five equivalent posynomial GP problem formulations. Four of these codes were general NLP codes; six were specialized GP codes. A total of forty-two test problems was solved with up to twenty randomly generated starting points per problem. The convex primal formulation is shown to be intrinsically easiest to solve. The general purpose GRG code called OPT appears to be the most efficient code for GP problem solution. The reputed superiority of the specialized GP codes GGP and GPKTC appears to be largely due to the fact that these codes solve the convex primal formulation. The dual approaches are only likely to be competitive for small degree of difficulty, tightly constrained problems.
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  • 9
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    Mathematical programming 22 (1982), S. 231-235 
    ISSN: 1436-4646
    Keywords: Integer Programming ; Covering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract LetA be a non-negative matrix with integer entries and no zero column. The integer round-up property holds forA if for every integral vectorw the optimum objective value of the generalized covering problem min{1y: yA ≥ w, y ≥ 0 integer} is obtained by rounding up to the nearest integer the optimum objective value of the corresponding linear program. A polynomial time algorithm is presented that does the following: given any generalized covering problem with constraint matrixA and right hand side vectorw, the algorithm either finds an optimum solution vector for the covering problem or else it reveals that matrixA does not have the integer round-up property.
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  • 10
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    Mathematical programming 22 (1982), S. 12-38 
    ISSN: 1436-4646
    Keywords: Graph ; Matching ; Branching ; Linear Programming ; Polyhedron
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract Matching forests generalize branchings in a directed graph and matchings in an undirected graph. We present an efficient algorithm, the PMF Algorithm, for the problem: given a mixed graphG and a real weight on each of its edges, find a perfect matching forest of maximum weight-sum. The PMF Algorithm proves the sufficiency of a linear system which definesP = (G) andP(G), the convex hull of incidence vectors of perfect matching forests and matching forests respectively ofG. The algorithm also provides a generalization of Tutte's theorem on the existence of perfect matchings in an undirected graph.
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  • 11
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    Mathematical programming 22 (1982), S. 122-123 
    ISSN: 1436-4646
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  • 12
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    Mathematical programming 22 (1982), S. 141-147 
    ISSN: 1436-4646
    Keywords: Integer Rounding ; Pluperfect Graphs ; Combinatorial Optimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract LetA be a nonnegative integral matrix with no zero columns. Theinteger round-up property holds forA if for each nonnegative integral vectorw, the solution value to the integer programming problem min{1 ⋅y: yA ≥ w, y ≥ 0, y integer} is obtained by rounding up to the nearest integer the solution value to the corresponding linear programming problem min{1 ⋅y: yA ≥ w, y ≥ 0}. Theinteger round-down property is similarly defined for a nonnegative integral matrixB with no zero rows by considering max{1 ⋅y: yB ≤ w, y ≥ 0, y integer} and its linear programming correspondent. It is shown that the integer round-up and round-down properties can be checked through a finite process. The method of proof motivates a new and elementary proof of Fulkerson's Pluperfect Graph Theorem.
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  • 13
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    Mathematical programming 22 (1982), S. 236-237 
    ISSN: 1436-4646
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  • 14
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    Mathematical programming 22 (1982), S. 304-315 
    ISSN: 1436-4646
    Keywords: Location Theory ; Tree Networks ; Rigid Circuit Graphs ; Polynomial Algorithms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract We discuss several forms of thep-center location problems on an undirected tree network. Our approach is based on utilizing results for rigid circuit graphs to obtain polynomial algorithms for solving the model. Duality theory on perfect graphs is used to define and solve the dual location model.
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  • 15
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    Mathematical programming 23 (1982), S. 111-116 
    ISSN: 1436-4646
    Keywords: Multicriteria Optimization ; Convex Analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract Existence and characterization theorems for the efficient (nondominated) set of decisions inR n are presented. The existence is proved when the set of decisions satisfies some compactness conditions. The efficient set is characterized in terms of the exposed efficient decisions when certain convexity and compactness conditions are satisfied.
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  • 16
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    Mathematical programming 23 (1982), S. 170-180 
    ISSN: 1436-4646
    Keywords: Set Covering ; Heuristic Algorithms ; Worst Case Analysis ; Bounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract In [2], Chvatal provided the tight worst case bound of the set covering greedy heuristic. We considered a general class of greedy type set covering heuristics. Their worst case bounds are dominated by that of the greedy heuristic.
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  • 17
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    Mathematical programming 23 (1982), S. 216-226 
    ISSN: 1436-4646
    Keywords: Nonsmooth Optimization ; Subgradient ; Subdifferential ; Bundle Type Method ; Deletion Rule ; Resetting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract A numerical method for the unconstrained minimization of a convex nonsmooth function of several variables is presented. It is closely related to the ‘bundle type’ approach and to the conjugate subgradient method. A way is suggested to reduce the amount of information to be stored during the computational procedure. Global convergence of the method to the minimum is proved.
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  • 18
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    Mathematical programming 23 (1982), S. 326-340 
    ISSN: 1436-4646
    Keywords: Optimization ; Quasi-Newton ; Conjugate Gradient
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract In this paper we study conjugate gradient algorithms for large optimization problems. These methods accelerate (or precondition) the conjugate gradient method by means of quasi-Newton matrices, and are designed to utilize a variable amount of storage, depending on how much information is retained in the quasi-Newton matrices. We are concerned with the behaviour of such methods on the underlying quadratic model, and in particular, with finite termination properties.
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  • 19
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    Mathematical programming 23 (1982), S. 357-360 
    ISSN: 1436-4646
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  • 20
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    Mathematical programming 23 (1982), S. 1-19 
    ISSN: 1436-4646
    Keywords: Ellipsoid Algorithm ; Linear Programming ; Polynomial Boundedness ; Khachian's Method ; Linear Inequalities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract We give some modifications of the ellipsoid algorithm for linear programming and describe a numerically stable implementation. We are concerned with practical problems where user-supplied bounds can usually be provided. Our implementation allows constraint dropping and updates bounds on the optimal value, and should be able to terminate with an indication of infeasibility or with a provably good feasible solution in a moderate number of iterations.
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  • 21
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    Mathematical programming 23 (1982), S. 75-86 
    ISSN: 1436-4646
    Keywords: Constrained Optimization ; Global Convergence ; Nonlinear Programming ; Penalty Function ; Quasi-Newton Method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract The recently proposed quasi-Newton method for constrained optimization has very attractive local convergence properties. To force global convergnce of the method, a descent method which uses Zangwill's penalty function and an exact line search has been proposed by Han. In this paper a new method which adopts a differentiable penalty function and an approximate line is presented. The proposed penalty function has the form of the augmented Lagrangian function. An algorithm for updating parameters which appear in the penalty function is described. Global convergence of the given method is proved.
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  • 22
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    Mathematical programming 23 (1982), S. 193-205 
    ISSN: 1436-4646
    Keywords: Quasi-convexity ; Pseudo-Convexity ; Criteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract A first order criterion for pseudo-convexity and second order criteria for quasi-convexity and pseudo-convexity are given for twice differentiable functions on open convex sets. The relationships between these second order criteria and other known criteria are also analysed. Finally, the numbers of operations required to verify these criteria are calculated and compared.
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  • 23
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    Mathematical programming 23 (1982), S. 233-235 
    ISSN: 1436-4646
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  • 24
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    Mathematical programming 23 (1982), S. 236-236 
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  • 25
    ISSN: 1436-4646
    Keywords: Step-Length Selection ; Linesearch ; Non-Derivative Methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract A step-length algorithm is an essential part of many descent methods for unconstrained and constrained optimization. In this note we present a criterion that defines an acceptable step length when only function values are available at trial step lengths.
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  • 26
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    Mathematical programming 24 (1982), S. 326-345 
    ISSN: 1436-4646
    Keywords: Mathematical Programming ; Convex Functions ; Quasi-concave Functions ; Lagrangian ; Saddle-Points
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract A saddle-point duality is proposed for the quasi-concave non-differentiable case of the maximization of the minimum between a finite number of functions. This class of problems contains quasi-concave (convex) programs that are known to be irreducible to convex ones. With the aid of the saddle-point duality involving conjugate-like operators, a Lagrangian is presented, the saddle-points of which give the exact global solutions. A few particular cases are discussed, among them the Von Neumann economic model and discrete rational approximation.
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  • 27
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    Mathematical programming 24 (1982), S. 353-355 
    ISSN: 1436-4646
    Keywords: Global Minimization ; Linear Constraints ; Quadratic Concave Function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract A method is presented for the construction of test problems for which the global minimum point is known. Given a bounded convex polyhedron inR n , and a selected vertex, a concave quadratic function is constructed which attains its global minimum at the selected vertex. In general, this function will also have many other local minima.
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  • 28
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    Mathematical programming 22 (1982), S. 1-11 
    ISSN: 1436-4646
    Keywords: Graph ; Matching ; Branching ; Linear Programming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract We introduce the concept of matching forests as a generalization of branchings in a directed graph and matchings in an undirected graph. Given special weights on the edges of a mixed graph, we present an efficient algorithm for finding an optimum weight-sum matching forest. The algorithm is a careful application of known branching and matching algorithms. The maximum cardinality matching forest problem is solved as a special case.
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  • 29
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    Mathematical programming 22 (1982), S. 52-70 
    ISSN: 1436-4646
    Keywords: Duality ; Graph ; Matching ; Polytope
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract The matching polytope is the convex hull of the incidence vectors of all (not necessarily perfect) matchings of a graphG. We consider here the problem of computing the dimension of the face of this polytope which contains the maximum cardinality matchings ofG and give a good characterization of this quantity, in terms of the cyclomatic number of the graph and families of odd subsets of the nodes which are always nearly perfectly matched by every maximum matching. This is equivalent to finding a maximum number of linearly independent representative vectors of maximum matchings ofG; the size of such a set is called thematching rank ofG. We also give in the last section a way of computing that rank independently of those parameters. Note that this gives us a good lower bound on the number of those matchings.
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  • 30
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    Mathematical programming 22 (1982), S. 288-303 
    ISSN: 1436-4646
    Keywords: TheLDL T Factorization ; Symmetric Indefinite Matrices ; Symmetric Additions of Rows and Columns ; Partial Pivoting Strategies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract In an earlier paper [6] it is shown how the use of symmetric additions of rows and columns enables a stableLDL T factorization of symmetric indefinite matrices. In this paper we describe partial pivoting strategies. These strategies are faster than the complete pivoting strategies that were introduced in the first paper. Numerical experiments are included. The results show that some of the new strategies share the stable behaviour of complete pivoting while running almost as fast as the well-known Cholesky decomposition.
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    Mathematical programming 23 (1982), S. 87-110 
    ISSN: 1436-4646
    Keywords: Path Following ; PL Methods ; Predictor—Corrector Algorithms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract We consider path following methods designed to trace the zeroes of a continuous or differentiable mapF:R n+1 →R n . These methods are applicable e.g. in the numerical study of nonlinear eigenvalue and bifurcation problems. Traditionally a simplicial algorithm is based on a fixed triangulationT ofR n+1 and a corresponding piecewise linear approximationF T :R n+1 →R n .4 A fixed triangulation algorithm then traces the zeroes ofF T via a complementary pivoting procedure. We present two kinds of hybrid algorithms that have the structure of a predictor—corrector method using simplicial methods to carry out the corrector steps. Numerical experience is reported showing the improvement in efficiency as compared to the fixed triangulation algorithm.
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  • 32
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    Mathematical programming 22 (1982), S. 350-357 
    ISSN: 1436-4646
    Keywords: 0–1 Programming ; Nonlinear Integer Programming ; Cutting Planes ; Heuristics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract The purpose of this note is to present an accelerated algorithm for solving 0–1 positive polynomial (PP) problems. Like our covering relaxation algorithm (Management Science 1979), the accelerated algorithm is a cutting plane method, which uses the linear set covering problem as a relaxation for PP. However, a unique and novel feature of the accelerated algorithm is that it attempts to generate cutting planes from heuristic solutions to the set covering problem whenever possible. Computational results reveal that this strategy of generating cutting planes has led to a significant reduction in the computational time required to solve a PP problem.
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  • 33
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    Computing 29 (1982), S. 263-276 
    ISSN: 1436-5057
    Keywords: Fast Fourier transform ; FORTRAN radix 8 FFT ; recursive generation of trigonometric functions ; signal processing ; Schnelle Fouriertransformation ; FORTRAN Radix 8 FFT ; Generierung von trigonometrischen Funktionen ; Signalverarbeitung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Es werden neue, sich für FFT Algorithmen eignende rekursive Formeln zur Generierung von trigonometrischen Funktionen angegeben. Die Berechnung von einem trigonometrischen Koeffizientenpaar erfordert nur 2 Multiplikationen und 2 Additionen. Die Rechengeschwindigkeiten von verschiedenen Radix-2-,-4- und-8-FFT-FORTRAN-Realisierungen werden verglichen. Ein zeitsparendes, auf dem Radix-8-Algorithmus mit rekursiv generierten trigonometrischen Koeffizienten basiertes FORTRAN IV Programm wird geliefert.
    Notes: Abstract New recursive formulae for trigonometric functions generation suitable for FFT algorithms are given. Evaluation of one pair of trigonometric coefficients thus requires 2 multiplications and 2 additions only. Speed comparisons of various radices 2, 4 and 8 FFT FORTRAN realizations were performed. An efficient FORTRAN IV program for one-dimensional complex FFT based on radix 8 algorithm with recursively generated trigonometric coefficients is supplied.
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    Computing 29 (1982), S. 241-262 
    ISSN: 1436-5057
    Keywords: 5.32 ; 5.41 ; 8.3 ; Adjacent set ; branch-and-bound structure ; combinatorial programming ; depthfirst search ; discrete optimization ; essential block ; expansion tree ; optimal network partitioning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Diese Arbeit befaßt sich mit dem Problem der Zerlegung eines endlichen, zusammenhängenden, schlichten Graphen (Netz genannt) mit gewichteten Knoten und Kanten unter der Randbedingung, daß die Summe der Knotengewichte jedes einzelnen Teilgraphen eine vorgegebene Schranke nicht überschreitet. Gesucht ist die Menge der disjunkten Teilgraphen, welche ein minimales Gesamtgewicht der Kanten zwischen den Teilgraphen besitzt und die Randbedingung erfüllt. Ein neues Rechenverfahren zur Lösung dieses Problems wird vorgestellt, das in der Lage ist, mit vertrebarem Rechenaufwand große Netze optimal zu zerlegen. Auf dem Konzept „Teile und herrsche” beruhend, wird das Problem in mehrere Teilprobleme zerlegt, die nacheinander mittels „depth-first search” und „branch-and-bound” gelöst werden. Die wesentlichen Rechenschritte bestehen aus Additionen, Vergleichen, und logischen Verknüpfungen von booleschen Vektoren.
    Notes: Abstract The problem considered is to partition an edge-valued, node-weighted, finite, connected, simple graph (called a network) into disjoint subgraphs, each of which has a total node weight that does not exceed a weight constraint, and so that the total value of edges interconnecting the subgraphs is minimized. This paper presents a new approach which is effective in solving the problem, and fast enough to be practical in finding optimal partitions of large networks. It uses the concept of “divide and conquer” to partition the problem into several subproblems, which can be efficiently solved one after the other by using depth-first search and branch-and-bound principle. The operations required under the algorithms are additions, comparisons, and logical operations on binary vectors.
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    Computing 29 (1982), S. 277-287 
    ISSN: 1436-5057
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Abstract The mathematical background of some recently proposed cryptographic systems is investigated. The analysis of the mathematics behind these systems, leads to extensions and shows how to avoid insecurity.
    Notes: Zusammenfassung Der mathematische Hintergrund einiger Chiffrierverfahren, die neuerdings vorgeschlagen werden, wird untersucht. Die genaue Analyse der benutzten mathematischen Aussagen führt zu Erweiterungen der Verfahren und zeigt, welche Vorkehrungen nötig sind, um Sicherheit vor unbefugter Entschlüsselung zu erreichen.
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    Computing 29 (1982), S. 309-326 
    ISSN: 1436-5057
    Keywords: Nonlinear regression ; Gauss-Newton-Method ; homotopy method ; stepsize control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Abstract For adequate models of nonlinear regression the homotopy method is shown to enlarge the region of convergence of the ordinary Gauss-Newton-Method theoretically as well as practically. Two methods to control the stepsize are proposed: the first one is in analogy to the empirically based „doubling-/bisecting-” damping strategy for the relaxed Newton Method and the other one is based upon more local information of the function. Both methods are shown to be effective with practical problems and improve the old method of a constant stepsize; in addition the second method can follow the homotopy path and can even detect it's singularities. In case of a system of nonlinear equations both methods reduce to a stepsize control for the embedded Newton method.
    Notes: Zusammenfassung Für adäquate nichtlineare Ausgleichsprobleme wird gezeigt, daß die Homotopiemethode den Konvergenzbereich des gewöhnlichen Gauß-Newton-Verfahrens sowohl theoretisch wie praktisch beträchtlich vergrößern kann. Für die Steuerung der Homotopieschrittweite werden zwei Methoden vorgeschlagen: die erste ist analog zur „Verdopplungs-/Halbierungs-” Strategie beim gedämpften Newtonverfahren, während die zweite zum Teil lokale Informationen über die betrachtete Funktion miteinbezieht und damit dem Homotopiepfad folgen und auftauchende Singularitäten entdecken kann. Für praktische Probleme stellen beide Methoden eine Verbesserung gegenüber der Methode der konstanten Schrittweiten dar und beide reduzieren sich bei nichtlinearen Gleichungssystemen auf eine Schrittweitensteuerung für das „eingebettete” Newtonverfahren.
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    Computing 29 (1982), S. 289-307 
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    Description / Table of Contents: Zusammenfassung In dieser Arbeit wird ein Algorithmus zur Minimierung einer nichtlinearen Funktion unter nichtlinearen Ungleichungsnebenbedingungen diskutiert. Ausgangspunkt der Betrachtungen ist die in diesem Journal erschienene Arbeit von Best/Bräuninger/Ritter/Robinson. Die dort vorgeschlagene Kombination einer Strafmethode mit dem Robinsonverfahren kann verallgemeinert werden, indem man das Prinzip der Kopplung auf eine ganze Klasse lokal konvergenter Verfahren überträgt. Als Beispiel wird eine diskretisierte Version des Wilsonverfahrens angeführt, welche sich dahingehend als vorteilhaft erweist, daß dabei lineare Gleichungssysteme als Teilprobleme auftreten. Diese sind bei ausreichend fortgeschrittener Iteration eindeutig lösbar. Die in der Startphase notwendige Minimierung von Straffunktionen erfolgt asymptotisch exakt. Insgesamt ist damit die Implementierbarkeit des Verfahrens gesichert. Die angegebenen Konvergenzaussagen werden in der Hauptsache unter Benutzung des Banachschen Fixpunktsatzes verifiziert und stimmen im wesentlichen mit den Ergebnissen in der oben erwähnten Arbeit überein. Es zeigt sich, daß die Voraussetzungen für die Konvergenz des Verfahrens abgeschwächt werden können. Für die speziellen Verfahren, die durch die Verwendung der einzelnen konsistenten Approximationen der Hesse-Matrix der Lagrange-Funktion entstehen, ergeben sich die aus der Behandlung nichtlinearer Gleichungen bekannten Abschätzungen derR-Ordnung.
    Notes: Abstract This paper discusses an algorithm for the minimization of a nonlinear objective function subject to nonlinear inequality constraints. The considerations are influenced by a paper of Best/Bräuninger/Ritter/Robinson (published in this journal). Their idea of combining a penalty-method with Robinson's method can be generalized by extending the principle of coupling to a whole class of locally convergent algorithms. An example is given by using a discretized version of Wilson's method, advantageously in the following sense: During the second phase, only linear equations occur in the subproblems. After a sufficiently large number of iterations, these systems are uniquely solvable. The minimization of penalty functions, necessary in the first phase, is asymptotically exact. Altogether, the implementability of the method can be guaranteed. The given convergence results are verified by using Banach's fixed-point theorem mainly. On the whole, they correspond with the paper mentioned above. The assumptions for proving global convergence are permitted to be weaken. By using different consistent approximations of the Hessian of the Lagrange function several methods arise, which have estimates of theR-order well-known from the treatment of nonlinear equations.
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    Computing 29 (1982), S. 327-336 
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    Keywords: 65T05 ; 42B05 (Primary) ; 65D07 (Secondary) ; Fourier coefficients ; natural spline functions ; interpolation
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    Description / Table of Contents: Zusammenfassung Betrachtet wird die numerische Berechnung von komplexen Fourier-Koeffizienten für nichtperiodische und reelle Funktionenf(x)(x∈[a, b], −∞〈a〈b〈∞). Die Methode beruht auf einer Approximation vonf(x) mit Hilfe von natürlichen Spline-Funktionens (mit beliebigen Knotenpunkten und der Grad 2q−1;q≥1), welchef in den Knotenpunkten vons interpolieren. Berechnet werden die genauen Fourier-Koeffizienten vons, und diese dienen als Approximation für die genauen Werte der Fourier-Koeffizienten vonf.
    Notes: Abstract This paper deals with numerical evaluation of complex Fourier coefficients of the nonperiodic and real-valued functionf(x)(x∈[a, b], −∞〈a〈b∞). Our method consists in approximatingf(x) by the natural spline functions (with arbitrary knots and degree 2q−1;q≥1) interpolatingf at the knots ofs. The exact Fourier coefficients ofs are derived and they serve as approximations for the exact values of the Fourier coefficients off.
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    Computing 29 (1982), S. 361-364 
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    Description / Table of Contents: Zusammenfassung Für eine Folge von Netzen auf [0, 1] werden hinreichende Bedingungen angegeben, so daß die kubischen Interpolationssplines für stetige Funktionen gleichmäßig konvergieren. Diese Bedingungen erweisen sich auch als hinreichend für die gleichmäßige Konvergenz der dritten Ableitungen der kubischen Interpolationssplines für Funktionen ausC 3 [0, 1].
    Notes: Abstract For a sequence of meshes on [0, 1] sufficient conditions are given to obtain uniform convergence of cubic spline interpolants for continous functions respectively for the third derivatives of cubic spline interpolants for functions fromC 3 [0, 1].
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    Computing 29 (1982), S. 355-359 
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    Description / Table of Contents: Zusammenfassung Eine Bemerkung zur Methode von King über die Berechnung einer Nullstelle mit Vorzeichenwechsel, die in einem Intervall eingeschlossen ist. Die hier vorgeschlagene Modifikation besteht darin, den Sekantenschnitt und die Snyder-Hilfsschritte der Methode von King durch Bisektionsschritte zu ersetzen. Tests haben ergeben, daß diese Modifikation effektiver ist als die ursprüngliche Methode von King.
    Notes: Abstract In this paper a modification of the King's methodF for finding a bracketed root is presented in which the first-secant step and the auxiliary Snyder's steps are replaced by bisection steps. It is shown that modified algorithm is more effective than King's procedure. Two FORTRANIV subroutines are included.
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    Computing 29 (1982), S. 337-354 
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    Keywords: Primary 65D30 ; Cauchy principal value integrals ; poles ; quadrature rules ; convergence ; algorithms
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    Description / Table of Contents: Zusammenfassung In dieser Arbeit untersuchen wir die numerische Integration (d. h. die Bestimmung des Hauptwertes im Sinne von Cauchy) von Funktionen mit mehreren reellen Polen erster Ordnung. Wir beschreiben Quadraturformeln vom interpolatorischen Typus, die von Delves, Hunter, Elliott-Paget und anderen Autoren gegeben sind: einige einfache Verallgemeinerungen werden vorgeschlagen und berechnungstechnische Fragen werden diskutiert. Endlich geben wir einen alternativen Algorithmus zum Ausrechnen von Integralen der Form
    Notes: Abstract In this paper we examine the numerical integration (in the Cauchy principal value sense) of functions having (several) first order real poles. We give a survey of results concerning some quadrature formulas of interpolatory type proposed by Delves, Hunter, Elliott and Paget, and several other authors; along with the description we present some minor generalizations and make comments on the computational aspects. Finally, we propose an alternative algorithm for the numerical evaluation of integrals of the form
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    Computing 29 (1982), S. 365-371 
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    Description / Table of Contents: Zusammenfassung Ein einfacher Algorithmus zur gleichzeitigen Berechnung der Werte und der Ableitungen höherer Ordnung eiňerB-Spline-Reihe wird untersucht.
    Notes: Abstract A simple algorithm is presented for computing the value together with all derivatives up to a specified order of aB-spline series.
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    Computing 29 (1982), S. 373-380 
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    Keywords: 68C25 ; 68C20 ; Analysis of algorithms ; computational complexity ; cost complexity ; Ruffini-Horner method ; polynomial evaluation ; polynomial translation ; computer algebra ; unlimited precision arithmetic
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    Description / Table of Contents: Zusammenfassung Die Verminderung der Zahl der Multiplikationen bei der Berechnung eines Polynoms und seinen Ableitungen bringt nicht unbedingt eine entsprechende Verminderung der gesamten Berechnungskosten. In dieser Arbeit werden Kosten-Analysen einer Algorithmen-Familie vorgestellt, die alle Ableitungen eines Polynoms mit 3n−2 Multiplikationen oder Divisionen berechnet. Dies repräsentiert eine Verbesserung im Vergleich mit den klassischen Methoden, die 1/2n(n+1) Multiplikationen benötigen. Jedoch offenbart die Analyse die Gegenwart eines Ausgleichs zwischen den Kosten der Multiplikationen bzw. Divivionen und den übrigen Kosten. Dadurch bleibt die Komplexität für alle AlgorithmenO(ξ2 n 3), wie stark auch immer die Verminderung der Zahl der arithmetischen Operationen ist.
    Notes: Abstract Reducing the number of multiplications for the evaluation of a polynomial and its derivatives does not necessarily mean that one should expect a commensurate reduction of the total cost of computation. In this paper we present a cost analysis for a family of algorithms, which computes all derivatives of a polynomial in 3n−2 multiplications or divisions. This represents an improvement over the classical methods, which require 1/2n(n+1) multiplications. The analysis, however, reveals the presence of a multiplications-divisions cost trade-off due to which the cost complexity remainsO(ξ2 n 3) for all algorithms irrespective of any reduction in the number of arithmetic operations.
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    Computing 28 (1982), S. 1-16 
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    Keywords: 65 F 15 ; Eigenvalues ; symmetric matrices ; parallelisation
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    Description / Table of Contents: Zusammenfassung Ein “alternierend sequentiell-paralleles” System (ASP) und dessen Vorteile gegenüber anderen Systemen werden diskutiert. Die Algorithmen von Jacobi, Givens und Householder werden so modifiziert, daß man sie auf diesem System ablaufen lassen kann. Für diese Methoden werden Wirkungsgrade berechnet. Es ergeben sich beachtliche Beschleunigungen.
    Notes: Abstract An “alternating sequential-parallel” system (ASP) is introduced, and its advantages over other models are discussed. Algorithms of Jacobi, Givens and Householder are modified for execution on this system. Efficiencies are computed for all methods and prove that the proposed methods achieve considerable speedups.
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    Computing 28 (1982), S. 43-51 
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    Keywords: spurious solutions ; discretizations ; nonlinear eigenvalue problems ; superlinear functions ; 34B15 ; 65H10 ; 65L10
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    Description / Table of Contents: Zusammenfassung Es werden endlich dimensionale, nichtlineare Eigenwertprobleme der FormAu=λFu mit einer MatrixA und einem Feld(Fu) i =f(u i ),i=1, ...,m betrachtet. Diese können als Diskretisierung eines entsprechenden Randwertproblems angesehen werden. Wir zeigen, daß diese diskreten Gleichungen dann zusätzliche, positive Lösungszweige (welche in [1,7] beobachtet wurden) aufweisen, wennf hinreichend stark wächst undA −1 mindestens zwei positive Spalten von einem bestimmten Typ besitzt. Ausführlicher, werden die Fällef(u)=e u undf(u)=u α behandelt, für die auch diskrete Verzweigungsdiagramme angegeben werden.
    Notes: Abstract We consider finite dimensional nonlinear eigenvalue problems of the typeAu=λFu whereA is a matrix and(Fu) i =f(u i ),i=1, ...,m. These may be thought of as discretizations of a corresponding boundary value problem. We show that positive, spurious solution branches of the discrete equations (which have been observed in some cases in [1, 7]) typically arise iff increases sufficiently strong and ifA −1 has at least two positive columns of a certain type. We treat in more detail the casesf(u)=e u andf(u)=u α where also discrete bifurcation diagrams are given.
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    Computing 28 (1982), S. 65-68 
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    Description / Table of Contents: Zusammenfassung Die formale Integration der Differential-Gl. zu einer Integral-Gl. ermöglicht die iterative Berechnung einer Klasse von kernspezifischen „Grund”-Funktionen, aus denen sich die Lösung des Randwertproblems linear aufbauen läßt.
    Notes: Abstract The formal integration of the differential eq. to an integral equation allows the iterative construction of a class of “basic” functions which, characterized by the kernel, are suitable for developing the solution to the boundary value problem.
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    Computing 28 (1982), S. 17-30 
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    Description / Table of Contents: Zusammenfassung Für reelle Intervallfunktionen wurde die zentrierte Form von R. E. Moore in seinem BuchInterval Analysis eingeführt [6]. Aufgrund numerischer Experimente vermutete er für die zentrierte Form quadratische Konvergenz auf den Wertebereich. Diese Vermutung wurde zuerst von Hansen [4] und später in allgemeinerer Form von Miller [5] bewiesen. In dieser Arbeit definieren wir eine zentrierte Form für komplexe Kreisintervallpolynome (siehe [3]). Wir zeigen, daß die zentrierte Form anders als im reellen Fall immer eine Verbesserung gegenüber dem Ausgangspolynom mit sich bringt. Ferner beweisen wir die quadratische Konvergenz, auf den komplexen Kreisintervall des Wertebereichs und schließlich legen wir einige numerische Beispiele vor.
    Notes: Abstract The centered form for real interval functions was first defined by R. E. Moore in his bookInterval Analysis [6]. Based on numerical experiments he conjectured that the centered form converges quadratically on the width of the range interval. The conjecture was first proved by Hansen [4] and later in a more general form by Miller [5]. In this paper a centered form is developed for circular complex interval polynomials (see [3]). This form is shown to always be an improvement on the power sum evaluation in contrast to the real case. The quadratic convergence of this form on the radius of the circular complex range interval is proved and some numerical examples are presented.
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    Computing 28 (1982), S. 289-303 
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    Keywords: 60K25 ; Fiducial intervals for the waiting time ; error estimates for the fiducial intervals ; batch system withn CPU's and Round-Robin algorithm ; Erlang- versus exponential distribution
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    Description / Table of Contents: Zusammenfassung Die vorliegende Arbeit befaßt sich mit Fehlerabschätzungen für Fiduzialintervalle ([0,a] heißt Fiduzial-Intervall zu (1-K) 100% Wahrscheinlichkeit fürW, fallsP {W〉a}=K) für die Wartezeit bei Schwankungen der mittleren CPU-Zeit und der Intensität. Dies wird für ein Batch-System mitn CPU's durchgeführt. Weiters werden für den Round-Robin-Algorithmus die Fiduzialintervalle für die bedingte ErwartungW(x)=E (Wartezeit‖CPU-Zeit=x) untersucht. Hierbei wird die Abhängigkeit der Fiduzial-Intervalle fürW(x) von der Verteilung der CPU-Zeiten analysiert (Erlangverteilung versus Exponentialverteilung). In allen Fällen werden Gleichungen oder Ungleichungen hergeleitet, die eine konkrete Berechnung gestatten.
    Notes: Abstract In this paper error-estimates for fiducial intervals for the waiting time are analyzed, the intensity and the mean CPU-time being submitted to variations; this is done for a batch-system withn CPU's. Moreover we consider fiducial intervals for the conditional exspectationW(x)=E(waiting time‖CPU-time=x) in the case of the Round-Robin algorithm. Especially we focus on the dependence of the fiducial intervals forW(x) upon the distribution of the CPU-time (Erlang- versus exponential distribution). The results are derived as equations or inequalities including the possibility of numerical computation.
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    Computing 28 (1982), S. 345-361 
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    Keywords: 65H10 ; 65N20 ; Coordinate relaxation ; global convergence ; diagonal dominance ; discrete obstacle problems ; quasilinear elliptic equations
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    Description / Table of Contents: Zusammenfassung Es werden einige neue Konvergenzsätze für eine allgemeine Klasse von Koordinatenrelaxationen zur Lösung nichtlinearer Gleichungssysteme bewiesen. Dabei wird die Existenz einer Skalierung der abhängigen oder unabhängigen Variablen vorausgesetzt, so daß die entstehende Funktionalmatrix spalten- bzw. zeilendiagonaldominant ist. Einer dieser Sätze wird übertragen auf die „Koordinatenrelaxation mit Projektion” zur Lösung diskretisierter Hindernisprobleme. Schließlich werden Beispiele zur Anwendbarkeit gegeben.
    Notes: Abstract We prove some new theorems on global convergence for a general class of coordinate relaxation schemes to solve systems of nonlinear equations. Those systems are assumed to admit a scaling of the dependent or independent variables such that the arising Jacobian is column or row diagonally dominant, resp. We extend one of these theorems to the case of coordinate relaxation with projection to solve discrete obstacle problems, and give examples for the application.
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    Mathematical programming 22 (1982), S. 82-92 
    ISSN: 1436-4646
    Keywords: Generic Programming ; Optimality Conditions ; Nonlinear Programming
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    Topics: Computer Science , Mathematics
    Notes: Abstract Optimality conditions for families of nonlinear programming problems inR n are studied from a generic point of view. The objective function and some of the constraints are assumed to depend on a parameter, while others are held fixed. Techniques of differential topology are used to show that under suitable conditions, certain strong second-order conditions are necessary for optimality except possibly for parameter values lying in a negligible set.
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    Mathematical programming 22 (1982), S. 261-287 
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    Keywords: Computational Efficiency ; Markovian Property ; Reduced Problem ; Reduced Gradient Method ; Conjugate Directions ; Quasi-Newton Method ; Quadratic Programming ; Storage Limitation ; Accuracy
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    Notes: Abstract This paper introduces the use of stochastic models for the evaluation of relative computational efficiency of algorithms. Such an approach is used for the comparison of computational efficiency of three algorithms for quadratic programming.
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    Mathematical programming 22 (1982), S. 316-331 
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    Keywords: Decomposition Algorithms ; Minimal Cut ; Flow Networks ; Lower Bounds
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    Notes: Abstract This paper provides decomposition algorithms for locating minimal cuts in a large directed network. The main theorem provides several cases for the algorithms. In the worst case, it is shown that the efficiency of one of the proposed algorithms is of the same order as a no-decomposition algorithm. As in linear programming, the obvious advantage of the proposed decomposition procedure is its ability to potentially handle larger problems than a no-decomposition algorithm.
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    Mathematical programming 23 (1982), S. 34-49 
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    Keywords: Linear Programming ; Variable Upper Bounds ; Degeneracy ; Triangular Factorization
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    Notes: Abstract Special methods for dealing with constraints of the formx j ≤ x k , called variable upper bounds, were introduced by Schrage. Here we describe a method that circumvents the massive degeneracy inherent in these constraints and show how it can be implemented using triangular basis factorizations.
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    Mathematical programming 23 (1982), S. 117-137 
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    Keywords: Polyhedral Combinatorics ; Polarity ; Blocking and Anti-blocking
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    Notes: Abstract LetX andY be finite dimensional vector spaces over the real numbers. LetΩ be a binary relation betweenX andY given by a bilinear inequality. TheΩ-polar of a subsetP ofX is the set of all elements ofY which are related byΩ to all elements ofP. TheΩ-polar of a subset ofY is defined similarly. TheΩ-polar of theΩ-polar ofP is called theΩ-closure ofP andP is calledΩ-closed ifP equals itsΩ-closure. We describe theΩ-polar of any finitely generated setP as the solution set of a finite system of linear inequalities and describe theΩ-closure ofP as a finitely generated set. TheΩ-closed polyhedra are characterized in terms of defining systems of linear inequalities and also in terms of the relationship of the polyhedronP with its recessional cone and with certain subsets ofX andY determined by the relationΩ. Six classes of bilinear inequalities are distinguished in the characterization ofΩ-closed polyhedra.
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    Mathematical programming 23 (1982), S. 181-192 
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    Keywords: Linear Complementarity Problem ; Stability ; Classes of Matrices
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    Notes: Abstract It has been shown previously that the Linear Complementarity Problem is stable when the defining matrix is positive semidefinite and when (locally) the set of solutions is nonempty and bounded. We enlarge the class of matrices for which this is true and also demonstrate how the boundedness condition leads to other stability type questions.
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    Mathematical programming 23 (1982), S. 227-232 
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    Keywords: Quadratic Bottleneck Assignment Problem ; Probabilistic Error Bounds
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    Notes: Abstract The relative error between best and worst solution of quadratic bottleneck assignment problems with cost coefficientsd ijpq =a ip b jq is considered, wherea ip is either arbitrarily given or corresponds to a distance in the plane. It is shown that the relative error is bounded by a function∈(m), tending to zero, with probability tending to one asm → ∞, provided the data are uniformly distributed. This implies that any algorithm for the above mentioned problems yields asymptotically an arbitrarily small relative error with probability tending to one.
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    Mathematical programming 23 (1982), S. 274-313 
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    Keywords: Large-Scale Optimization ; Linear Programming ; Staircase Linear Programs ; Simplex Method
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    Notes: Abstract This and a companion paper consider how current implementations of the simplex method may be adapted to better solve linear programs that have a staged, or ‘staircase’, structure. The present paper looks at ‘inversion’ routines within the simplex method, particularly those for sparse triangular factorization of a basis by Gaussian elimination and for solution of triangular linear systems. The succeeding paper examines ‘pricing’ routines. Both papers describe extensive (though preliminary) computational experience, and can point to some quite promising results.
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    Mathematical programming 24 (1982), S. 107-112 
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    Keywords: Lagrangian Subproblem ; Lagrangian Duality ; Non-linear Discrete Programming ; Separable Objective Function
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    Notes: Abstract This note presents an efficient method for the routine solution of the subproblem associated with the Lagrangian dual of discrete programming problems having separable non-linear objective function and linear constraints. An additional advantage for subgradient methods is described.
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    Mathematical programming 24 (1982), S. 113-116 
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    Mathematical programming 24 (1982), S. 117-121 
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    Mathematical programming 24 (1982), S. 137-161 
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    Keywords: Nonlinear Programming ; Exact Penalty Methods ; Successive Quadratic Programming
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    Notes: Abstract In this paper we motivate and describe an algorithm to solve the nonlinear programming problem. The method is based on an exact penalty function and possesses both global and superlinear convergence properties. We establish the global qualities here (the superlinear nature is proven in [7]). The numerical implementation techniques are briefly discussed and preliminary numerical results are given.
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    Mathematical programming 24 (1982), S. 236-240 
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    Mathematical programming 24 (1982), S. 284-313 
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    Keywords: Variational Inequality ; Complementarity ; Iterative Methods ; Convergence ; Traffic Equilibria
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    Notes: Abstract In this paper, we study both the local and global convergence of various iterative methods for solving the variational inequality and the nonlinear complementarity problems. Included among such methods are the Newton and several successive overrelaxation algorithms. For the most part, the study is concerned with the family of linear approximation methods. These are iterative methods in which a sequence of vectors is generated by solving certain linearized subproblems. Convergence to a solution of the given variational or complementarity problem is established by using three different yet related approaches. The paper also studies a special class of variational inequality problems arising from such applications as computing traffic and economic spatial equilibria. Finally, several convergence results are obtained for some nonlinear approximation methods.
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    Mathematical programming 24 (1982), S. 346-352 
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    Keywords: Least Absolute Values ; Chebychev Norm ; Regression ; Minimax ; Advanced Start ; Least Squares
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    Topics: Computer Science , Mathematics
    Notes: Abstract In exploratory data analysis and curve fitting in particular, it is often desirable to observe residual values obtained with different estimation criteria. The goal with most linear model curve-fitting procedures is to minimize, in some sense, the vector of residuals. Perhaps three of the most common estimation criteria require minimizing: the sum of the absolute residuals (least absolute value or L1 norm); the sum of the squared residuals (least squares or L2 norm); and the maximum residual (Chebychev or L∞ norm). This paper demonstrates that utilizing the least squares residuals to provide an advanced start for the least absolute value and Chebychev procedures results in a significant reduction in computational effort. Computational results are provided.
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    Computing 29 (1982), S. 1-9 
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    Description / Table of Contents: Zusammenfassung BezeichnetD G die Menge der Ableitungsbäume einer kontextfreien GrammatikG und $$T(\mathfrak{A})$$ die Menge der von einem endlichen Baumautomaten $$\mathfrak{A}$$ akzeptierten Bäume, dann gilt: Zu jeder kontextfreien GrammatikG und jedem Baumautomaten $$\mathfrak{A}$$ existiert eine strikte InterpretationG′ vonG und eine Yield-erhaltende Projektion π′ der Bäume über dem Alphabet vonG′ in die Menge der Bäume über dem Alphabet vonG derart, daß $$\pi '(D_{G'} ) = D_G \cap T(\mathfrak{A})$$ . Dies verallgemeinert ein bekanntes Resultat über Baumtransduktoren. Weiter wird gezeigt, daß im Falle einer eindeutigen GrammatikG zusätzlich gilt: (a) FürG′ kann ebenfalls eine eindeutige Grammatik gewählt werden, und (b) es existiert eine strikte InterpretationG″ vonG mitL(G″)=L(G)−L(G′).
    Notes: Abstract The following generalization of a well-known result in tree acceptors is established. For each context-free grammarG and tree acceptor $$\mathfrak{A}$$ there exists a strict interpretationG′ ofG and a yield-preserving projection π′ from the trees over the alphabet ofG′ into the trees over the alphabet ofG such that $$\pi '(D_{G'} ) = D_G \cap T(\mathfrak{A})$$ ,D G andD G′ being the derivation trees ofG′ andG respectively and $$T(\mathfrak{A})$$ the trees accepted by $$\mathfrak{A}$$ . Moreover, ifG is unambiguous, then (a)G′ can be chosen unambiguous, and (b) there is an unambiguous strict interpretationG″ ofG such thatL(G″)=L(G)−L(G′).
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    Computing 29 (1982), S. 11-29 
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    Keywords: 68C25 ; 68E99 ; Binary search trees ; height-balanced trees ; AVL trees ; weight-balanced trees
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Eine Methode, die von Yao formuliert und von Brown angewendet wurde, gestattet es, schranken für den Anteil von Knoten mit bestimmten Eigenschaften in Bäumen anzugeben, die durch eine Folge von zufälligen Einfügungen entstehen. Für den Fall von AVL-Bäumen (höhenbalanziert) zeigen wird, daß solche Methoden nicht erweitert werden können, um bessere Schranken als die bisher bekannten zu berechnen. Dann wenden wir diese Methode auf gewichtsbalanzierte Bäume und auf eine Art von “schwach balanzierten” Bäumen an und bestimmen die Verteilung der gewichtsbalanzierten Faktoren der inneren Knoten in einem Zufallsbaum, der durch binäre Suche und Einfügen entsteht; ferner zeigen wir, daß in einem solchen Baum ungefähr 72% der inneren Knoten gewichtsbalanzierte Faktoren zwischen $$1 - \sqrt 2 /2$$ und $$\sqrt 2 /2$$ haben.
    Notes: Abstract A method formulated by Yao and used by Brown has yielded bounds on the fraction of nodes with specified properties in trees bult by a sequence of random internal nodes in a random tree built by binary search and insertion, and show that in such a tree about bounds better than those now known. We then apply these methods to weight-balanced trees and to a type of “weakly balanced” trees. We determine the distribution of the weight-balance factors of the internal nodes in a random tree built by binary search and insertion and show that in such a tree about 72% of all internal nodes have weight balance factors lying between $$1 - \sqrt 2 /2$$ and $$\sqrt 2 /2$$ .
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    Computing 29 (1982), S. 51-61 
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    Keywords: 65L65 ; CR:5.17 ; Initial-value problems ; collocation methods ; A-stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Abstract The collocation methods treated by the author in [3] produce spline approximations for the solutions of initial value problems for ordinary differential equations. Some general results on A-stability given by Wanner, Hairer and Nørsett [6] are formulated for these methods in the case where they are equivalent to certain implicit Runge-Kutta-methods. Hereby the dependence of A-stability on the nodes and their their multiplicities becomes apparent.
    Notes: Zusammenfassung Die Kollokationsmethoden, die vom Autor in [3] untersucht werden, liefern Spline-Approximationen für die Lösungen von Anfangswertproblemen bei gewöhnlichen Differentialgleichungen. Einige allgemeine Resultate über A-Stabilität von Wanner, Hairer und Nørsett [6] werden für diese Methoden in dem Fall formuliert, wo sie mit gewissen impliziten Runge-Kutta-Methoden äquivalent sind. Hierbei wird die Abhängigkeit der A-Stabilität von den Knoten und ihren Vielfachheiten offensichtlich.
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    Computing 29 (1982), S. 31-49 
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    Description / Table of Contents: Zusammenfassung Wir geben parallele Algorithmen an, die in einem gerichteten, bewerteten Graphen die kürzesten Wege von einem Knoten (der Quelle) zu allen anderen Knoten liefern. Die Algorithmen sind für verschiedene Maschinentypen entworfen, die von Feldrechnern (Array-Prozessoren) über Vielfach-Befehle, Vielfach-Daten-Strom-Maschinen (MIMD) bis zu einem speziellen Netz von Prozessoren reichen Die Algorithmen sind durch “Paralleiisierung” von zwei klassischen sequentiellen Algorithmen entstanden — dem von Dijkstra (1959) und dem von Moore (1957). Unser Interesse besteht nicht nur in der Konstruktion schnell laufender paralleler Versionen. Wir untersuchen auch die Entwurfsprinzipien, die Gemeinsamkeiten der Korrektheitsbeweise in den verschiedenen Versionen und die subjektive Komplexität, die verschiedenen Fassungen zu verstehen und zu erklären.
    Notes: Abstract We present several parallel algorithms for the problem of finding shortest paths from a specified vertex (called the source) to all others in a weighted directed graph. The algorithms are for machines ranging from array processors, multipleinstruction multiple-data stream machines to a special network of processors. These algorithms have been designed by “parallelizing” two classic sequential algorithms — one due to Dijkstra (1959), the other due to Moore (1957). Our interest is not only in obtaining speeded-up parallel versions of the algorithms but also in exploring the design principles, the commonality of correctness proofs of the different versions, and the subjective complexity of explaining and understanding these versions.
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    Computing 29 (1982), S. 73-81 
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    Description / Table of Contents: Zusammenfassung Die Bestimmung der R-Ordnung τ von Folgen {x n, i ∼, die über ein System (3) von Ungleichungen miteinander verkoppelt sind, wird wie in der vorangegangenen Arbeit [3] auf die nichtnegative Lösbarkeit des Systems (4) von linearen Ungleichungen zurückgeführt. Weiterhin wird gezeigt, daß die beste R-Ordnung τ, welche sich aus (3) herleiten läßt, gleich dem Spektralradius einer bestimmten Matrix ist, welche aus in (3) auftretenden Exponenten gebildet wird.
    Notes: Abstract As in the preceding paper [3], the question whether some of the sequences {x n, i } coupled by a system (3) of inequalities converge at least with a certain R-order τ is reduced to the nonnegative solvability of the system (4) of linear inequalities. Further, the optimal R-order τ implied by (3) is characterized as the spectral radius of a certain matrix composed of exponents appearing in (3).
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    Computing 29 (1982), S. 63-72 
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    Keywords: 65G10 ; 65F05 ; Interval analysis ; interval inverse ; factorable function
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    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Für zweimal differenzierbare faktorisierbare Funktionen liefert ein neuer Algorithmus die Hessesche Matrix als Summe äußere Produkte von Vektoren und ein Hessesches Intervall als Summe von äußeren Produkten von Intervallvektoren. Eine praktische Methode zur Invertierung eines Hesseschen Intervalles einer faktorisierbaren Funktion, die diese Sonderstruktur ausnützt, wird hier vorgestellt. Über rechnerische Erfahrungen mit dieser Methode und andere Invertierungstechniken wird berichtet.
    Notes: Abstract For twice-differentiable factorable functions, a new computer code provides the Hessian matrix as the sum of outer products of vectors and an interval Hessian as the sum of outer products of interval vectors. A practical method for inverting an interval Hessian of a factorable function which exploits this special structure is presented. Computational experience with this method and other inversion techniques is reported.
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    Computing 29 (1982), S. 83-88 
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    Keywords: 65D30 (primary) ; 33A65 (secondary) ; Positive quadrature formulas
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    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Wir definieren mitS m die Menge der Werte (α, β), für welche die Interpolationsquadraturformel basierend auf den Nullstellen vonP m (α, β) (t) positive Gewichte besitzt. Im Gegensatz zu den Resultaten von Lether, Wilhelmsen und Frazier [5] zeigen wir, daßS m sich sehr regelmäßig verhält. Zu diesem Zweck ist es notwendig, die Fällem gerade undm ungerade zu unterscheiden. Weiters erhalten wir Informationen über die exakte Anzahl der negativen Gewichte außerhalb vonS m .
    Notes: Abstract This note is dedicated to the study ofS m , the set of (α,β) for which the interpolatory quadrature formula based on the zeroes ofP m (α,β)(t) has positive weights. In contract to the results published by Lether, Wilhelmsen and Frazier [5], we show thatS m behaves very regularly. The point is that the casesm odd andm even must be distinguished. Furthermore, informations on the exact number of negative weights for values outside ofS m are obtained.
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    Computing 29 (1982), S. 113-133 
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    Description / Table of Contents: Zusammenfassung Wir betrachten zwei verschiedene Ansätze für Gruppenflüsse in einem regulären MatroidM=(E,C). Indem wir zeigen, daß diese beiden Ansätze äquivalent sind, erhalten wir eine Zerlegungstheorie für Matroidflüsse in regulären Matroiden und leiten daraus zwei Algorithmen zur Zerlegung von Matroidflüssen ab. Der zweite Algorithmus findet eine sogenannte positive Zerlegung, eine Tatsache, die für Anwendungen sehr wichtig ist. Durch Spezialisierung der Resultate auf graphische und cographische Matroide verallgemeinern wir einige bekannte Resultate der reellwertigen Netzwerkflußtheorie auf Gruppen-Netzwerkflüsse und erhalten neue Resultate für Spannungsprobleme.
    Notes: Abstract In a regular matroidM=(E,C) we discuss two different approaches to group matroid flows. By showing that these two approaches are equivalent we set up a decomposition theory for group matroid flows and derive two algorithms for decomposing group matroid flows. The second one finds so-called positive decomposition, a fact which is highly important in applications. By specializing the results to graphic and co-graphic matroids we generalize some well known results of real-valued network flow theory to group network flows and derive some new results for tensions.
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    Computing 29 (1982), S. 89-112 
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    Keywords: 68F05 ; Graph ; graph grammars ; embedding tranformation ; sequential replacement ; parallel replacement ; generative power
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Programmierte Graph-Grammatiken werden formal definiert und bezüglich ihrer generativen Mächtigkeit untersucht. Programmierte Graph-Grammatiken unterscheiden sich von anderen Graph-Grammatik-Ansätzen durch das sogenannte Kontrolldiagramm, welches die Reihenfolge steuert, in der Produktionen angewendet werden. Durch Einschränkung der Gestalt der Produktionen erhält man verschiedene Klassen von Graph-Sprachen. Diese werden untereinander sowie mit der von Nagl [18] eingeführten Hierarchie verglichen. Im Falle von uneingeschränkten und monotonen Produktionen fallen einander entsprechende Klassen von Graph-Sprachen zusammen, während die Klasse der kontextfreien programmierten Graph-Sprachen echt enthalten ist in der Klasse der kontextfreien Graph-Sprachen nach [18].
    Notes: Abstract Programmed graph grammars are formally introduced and their generative power is investigated. Programmed graph grammars differ from other approaches to graph grammars in the so-called control diagram which controls the application order of productions. Restricting the form of the productions of a programmed graph grammar we get several classes of graph languages. These are compared mutually as well as with the hierarchy introduced by Nagl [18]. For unrestricted and monotone productions corresponding classes of graph languages coincide, while the class of context free programmed graph languages is properly contained in the class of context free graph languages in the sense of [18].
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  • 74
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    Keywords: 65L05 ; CR: 5.17 ; Numer. Analysis ; verallgemeinerte Runge-Kutta-Methoden ; steife Probleme
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Abstract Adaptive Runge-Kutta-methods are considered. Investigations of stability for these linear implicit methods are studied. For the application a LS-stable method of order four with an adaptive stepsize control is proposed. Test results for 25 stiff initial value problems for different tolerances are discussed.
    Notes: Zusammenfassung Es werden adaptive Runge-Kutta-Verfahren betrachtet und Stabilitätsuntersuchungen für diese linear impliziten Methoden durchgeführt. Für die Anwendung wird ein LS-stabiles Verfahren vierter Ordnung mit einer angepaßten Schrittweitenkontrolle vorgeschlagen. Testergebnisse von 25 stiff Anfangswertproblemen für verschiedenen Toleranzen werden diskutiert.
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    Computing 29 (1982), S. 135-152 
    ISSN: 1436-5057
    Keywords: Primary: 33A20 ; secondary: 30A04, 3A22, 41A20, 41A21, 65D20, 65G05 ; Gaussian error function ; continued fraction expansion ; truncation error
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Der Abbruchfehler für eine Kettenbruchentwicklung zum Gaußschen Fehlerintegral wird beidseitig abgeschätzt. Die Güte der Abschätzungen wird durch Vergleich mit den exakten Werten geprüft. Die zugehörige erreichbare Genauigkeit sowie die Anzahl der benötigten Iterationen werden in verschiedener Weise diskutiert.
    Notes: Abstract The truncation error for a continued fraction to the Gaussian error function is estimated. The precision of the obtained bounds is verified by comparison with the exact values. The related precision as well as the number of needed iterations are discussed in several ways.
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    Computing 29 (1982), S. 167-173 
    ISSN: 1436-5057
    Keywords: Primary 65F10 ; secondary 65N10 ; Jacobi iterative method ; preconditioning parameter ; generalized Dirichlet problem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Die Arbeit behandelt die Anwendung von Vorkonditionierungstechniken auf das bekannte Iterationsverfahren von Jacobi zur Lösung der Differenzengleichungen, die bei der Diskretisierung selbstadjungierter elliptischer partieller Differentialgleichungen entstehen. Die Konvergenzeigenschaften dieses einparametrigen Vorkonditionnierungsverfahrens werden untersucht, die Werte des optimalen Parameters und das Verhalten der Methode werden für verschiedene Standardprobleme bestimmt.
    Notes: Abstract This paper is concerned with the application of preconditioning techniques to the well known Jacobi iterative method for solving the finite difference equations derived from the discretization of self-adjoint elliptic partial differential equations. The convergence properties of this one parameter preconditioned method are analyzed and the value of the optimum preconditioning parameter and the performance of the method determined for a variety of standard problems.
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    Computing 29 (1982), S. 175-181 
    ISSN: 1436-5057
    Keywords: 62J05 ; 62H30 ; 65F20 ; 65D10 ; Cluster analysis ; linear regression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Für einen früher publizierten Algorithmus [5] wird eine schnelle Implementation angegeben.
    Notes: Abstract A fast implementation of a formerly [5] published algorithm is given.
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    Computing 29 (1982), S. 183-200 
    ISSN: 1436-5057
    Keywords: 65H10 ; 65G05 ; 65D99 ; Automatic verification ; existence ; uniqueness ; inclusion ; rounding error ; condition number ; residue
    Source: Springer Online Journal Archives 1860-2000
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    Description / Table of Contents: Zusammenfassung Im folgenden wird ein Algorithmus zur Konstruktion einer Einschließung einer Lösung eines nichtlinearen Gleichungssystems angegeben. Im Gegensatz zu bekannten Methoden benötigt der Algorithmus keine schwierig verifizierbaren Voraussetzungen wie etwa die Nichtsingularität einer Matrix. Tatsächlich wird diese Eigenschaft vom Algorithmus automatisch verifiziert. Die Ergebnisse des Algorithmus zeichnen sich durch hohe Genauigkeit aus. Diese wird durch Residuen (eventuell höherer Ordnung) erreicht.
    Notes: Abstract We give an algorithm for constructing an inclusion of the solution of a system of nonlinear equations. In contrast to existing methods, the algorithm does not require properties which are difficult to verify such as the non-singularity of a matrix. In fact this latter property is demonstrated by the algorithm itself. The highly accurate computational results are obtained in terms of a residue of first or higher order of the system.
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    Computing 29 (1982), S. 201-226 
    ISSN: 1436-5057
    Keywords: 65H10 ; 73H05 ; Turning points ; algorithms ; experimental comparison
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung In vielen Gleichgewichtsproblemen ist die Bestimmung der Lage von Umkehrpunkten von Bedeutung, wo möglicherweise ein Stabilitätsverlust eintreten kann. Eine Anzahl von Algorithmen für die Berechnung solcher Punkte ist bekannt. Diese Arbeit enthält experimentelle Vergleichsresultate für insgesamt sechzehn Variationen von zehn solchen Methoden. Hierfür wurden sieben Versuchsprobleme verschiedener Dimension mit 27 Umkehrpunkten benutzt. Die Resultate deuten auf eine Reihe von Schlüssen über den relativen praktischen Wert dieser Methoden.
    Notes: Abstract In the study of many equilibrium problems it is important to determine the location of turning points which may signify a loss of stability. A number of algorithms is known for the computation of such points. In this paper experimental comparisons are presented of a total of sixteen variations of ten such methods. For this a set of seven test problems of varying dimension with a total of 27 turning points were used. The results suggest a number of conclusions about the relative practical merits of these methods.
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    Computing 29 (1982), S. 227-239 
    ISSN: 1436-5057
    Keywords: 68C25 ; Bin packing ; approximation algorithms ; stochastic algorithms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Beim eindimensionalen Packungsproblem besteht die Aufgabe darin, eine Liste vonn Eingabegrößen in möglichst wenige “Behälter” der Höhe 1 zu packen. Es wird eine Klasse von linearen Online-Algorithmen zur näherungsweisen Lösung des Packungsproblems mit Eingabegrößen, die einer bekannten Wahrscheinlichkeitsverteilung unterliegen, vorgestellt. Jeder dieser Algorithmen hängt von der Wahrscheinlichkeitsverteilung und einem Parameter ab, der die Güte des Algorithmus beeinflußt. Es wird gezeigt, daß sich der Erwartungswert der relativen Packungsdichte bei wachsender Anzahl der Eingabegrößen beliebig dicht dem Optimum nähert.
    Notes: Abstract In the one-dimensional bin packing problem a list ofn items has to be packed into a minimum number of unit-capacity bins. A class of linear online algorithms for the approximate solution of bin packing with items drawn from a known probability distribution is presented. Each algorithm depends on the distribution and on a parameter controlling the performance of the algorithm. It is shown that with increasing number of items the expected performance ratio has an arbitrary small deviation from optimum.
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    Computing 28 (1982), S. 257-267 
    ISSN: 1436-5057
    Keywords: Combinatorial algorithms ; probabilistic analysis ; 90
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    Description / Table of Contents: Zusammenfassung Wahrscheinlichkeitstheoretische Methoden zur Bewertung der Effizienz kombinatorischer Optimierungsverfahren finden wachsendes Interesse, und man beobachtet ein rasches Wachstum der Forschungstätigkeit auf diesem Gebiet. Der vorliegende Bericht ist eine Bibliographie über 70 Arbeiten, die sich mit der wahrscheinlichkeitstheoretischen Bewertung der Zeitkomplexität und der Genauigkeit deterministischer Algorithmen für kombinatorische Entscheidungs- und Optimierungsprobleme beschäftigen. Einige Arbeiten, im wesentlichen aus Zeitschriften und unregelmäßig erscheinenden Publikationen mit geringer Auflage, werden kurz diskutiert (18 Zitate). Grundlegende Bezeichnungen und Definitionen, die Verständnis und Darstellung der Ergebnisse erleichtern, sind angegeben.
    Notes: Abstract Probabilistic methods in evaluation of performance efficiency of combinatorial optimization algorithms are of continuously growing interest, and rapidly increasing effort of researchers in this field is observed. The present paper is a bibliography which contains 70 references dealing with probabilistic evaluation of time complexity and performance accuracy of deterministic algorithms for combinatorial decision and optimization problems. Some entries of the bibliography, mainly those having appreared in journals and nonperiodical issues of limited distribution are shortly annotated (18 references). Basic notions and definitions facilitating better understanding and plain presentation of different results are given.
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    Computing 28 (1982), S. 53-63 
    ISSN: 1436-5057
    Keywords: Polygonal domains ; singular expansion ; 65N30
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    Description / Table of Contents: Zusammenfassung Es wird eine Finite Elemente Methode zur Approximation elliptischer Differentialgleichungen auf Eckengebieten vorgeschlagen. Das Verfahren benutzt die Singulärfunktionen des Problems im Raum der Ansatzfunktionen und die Kernfunktionen des adjungierten Operators im Testraum. Dadurch erhält man gute Näherungen der Koeffizienten, der Singulärfunktionen. In einem numerischen Beispiel wird das Verfahren mit der bekannten Methode der Singulärfunktionen verglichen.
    Notes: Abstract A finite element method for approximating elliptic equations on domains with corners is proposed. The method makes use of the singular functions of the problem in the trial space and the kernel functions of the adjoint problem in the test space. This leads to good approximates of the coefficients of the singular functions. In the numerical computations, the method is compared with the well known Singular Function Method.
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    Computing 28 (1982), S. 31-42 
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    Keywords: E-method ; inclusion ; automatic verification ; 65 H 99
    Source: Springer Online Journal Archives 1860-2000
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    Description / Table of Contents: Zusammenfassung Es werden neuartige sehr allgemeine Methoden vorgestellt, die sowohl eine Einschließung der Lösung von Fixpunktgleichungenf(x)=x als auch automatisch dieExistenz und gegebenenfallsEindeutigkeit der Lösung nachweisen. Diese Methoden machen wesentlichen Gebrauch von neuen Rechnerarithmetiken, die charakterisiert sind wie in [2], [7] und [8] entwickelt. Wir nennen solche Methoden E-Methoden in Übereinstimmung mit den drei Anfangsbuchstaben. A-priori-Abschätzungen wie z. B. für Schranken von Lipschitzkonstanten sind nicht mehr notwendig. Daher ist es in eleganter Weise möglich, Algorithmen zu implementieren, die einen automatischen Existenz- und Eindeutigkeitsnachweis für den Fixpunkt von linearen und nichtlinearen Fixpunktgleichungen ermöglichen. Die mit E-Methoden berechneten Lösungen haben i. a. eine relative Genauigkeit, die besser als 10−t+1 ist (wobeit die Mantissenlänge des verwendeten Rechners bezeichnet).
    Notes: Abstract This paper provides newly implemented [11], [13] and widely applicable methods for, computing inclusion (i. e. a containing interval) (Einschließung) of the solution of a fixed point equationf(x)=x as well as autmatic verification the existence (Existenz) and uniqueness (Eindeutigkeit) of the solution. These methods make essential use of a new computer arithmetic defined by semimorphisms as developed in [7] and [8]. We call such methods E-Methods in correspondance to the three German words. A priori estimations such as a bound for a Lipschitz constant etc. are not required by the new algorithm. So the algorithm including the a posteriori proof of existence and uniqueness of the fixed point is programmable on computers for linear as well as for nonlinear problems. This is a key feature of our results. The computations produced by E-methods deliver answers the components of which have accuracy better than 10−t+1 (wheret denotes the mantissa length employed in the computer).
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    Computers and the humanities 16 (1982), S. 11-18 
    ISSN: 1572-8412
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    Topics: Computer Science , Media Resources and Communication Sciences, Journalism
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    Computers and the humanities 16 (1982), S. 1-9 
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    Computers and the humanities 16 (1982), S. 19-24 
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    Computers and the humanities 16 (1982), S. 35-37 
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    Computers and the humanities 16 (1982), S. 39-40 
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    Computers and the humanities 16 (1982), S. 41-42 
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    Computers and the humanities 16 (1982), S. 43-57 
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    Computers and the humanities 16 (1982), S. 67-68 
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    Computers and the humanities 16 (1982), S. 107-117 
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    Computers and the humanities 16 (1982), S. 59-65 
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    Computers and the humanities 16 (1982), S. 69-84 
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    Notes: Abstract The subject of this article is a brief survey of dialectometry, which is defined according to the following equation: linguistic geography+numerical taxonomy=dialectometry. First dealt with are problems concerning the processing of raw data, the coding, scaling, measurement and compilation of the data matrix (atlas points×atlas maps). After the description of the similarity coefficient used and the compilation of the similarity matrix it will be shown how the individual vectors of the similarity matrix can be visualized in the form of choropleth maps and three-dimensional surfaces. These visualized vectors of the similarity matrix are described as similarity maps. After consideration of the usefulness of such similarity maps for genuine linguistic geography there is a discussion of other possible fields which will be opened up as a result of intensified dialectometrical research (e.g. graph theory, network theory, game theory). This article is supplemented by 9 figures, 2 tables and an extensive bibliography.
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    Computers and the humanities 16 (1982), S. 85-105 
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    Computers and the humanities 16 (1982), S. 119-129 
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    Computers and the humanities 16 (1982), S. 137-143 
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    Computers and the humanities 16 (1982), S. 157-164 
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    Computers and the humanities 16 (1982), S. 145-155 
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    Topics: Computer Science , Media Resources and Communication Sciences, Journalism
    Notes: Conclusions (1) Microcomputers may render the same services to the individual museums as mainframes and/or networks. When a sizable amount of data is entered in several museums they may be integrated in ‘loosely coupled systems’, that share data as and when required. (2) The museum staff is motivated more readily by working with a small in-house system that they may control themselves than when they have to work with a system, however extended the help and facilities it provides, that is outside their control. (3) Data for an automated system may correspond in format to the traditional ones for manual documentation. (4) The input format should be easily manipulable, both at programming level and from the user's point of view. This ‘user friendliness’ should provide an efficient use of manpower resources, e.g., by concentrating on a few selected fields, by copying fields with identical entries, etc. (5) If the retrieval program incorporates three essential components—AND/OR/NOT operators, full field control and inverted file searching—a high precision-recall ratio may be expected, even when relatively few fields are used.
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