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Displaying 41 –
60 of
319
In this article, given a reference feasible trajectory of an optimal control problem, we say that the quadratic growth property for bounded strong solutions holds if the cost function of the problem has a quadratic growth over the set of feasible trajectories with a bounded control and with a state variable sufficiently close to the reference state variable. Our sufficient second-order optimality conditions in Pontryagin form ensure this property and ensure a fortiori that the reference trajectory...
Una forma habitual de secuenciar de modo dinámico los trabajos en los sistemas de fabricación es mediante el empleo de reglas de secuenciación. Sin embargo, el problema que presenta este método es que el comportamiento del sistema de fabricación dependerá de su estado, y no existe una regla que supere a las demás en todos los posibles estados que puede presentar el sistema de fabricación. Por lo tanto, sería interesante usar en cada momento la regla más adecuada. Para lograr este objetivo, se pueden...
The paper presents selected multicriteria (multiobjective) approaches to shortest path problems. A classification of multi-objective shortest path (MOSP) problems is given. Different models of MOSP problems are discussed in detail. Methods of solving the formulated optimization problems are presented. An analysis of the complexity of the presented methods and ways of adapting of classical algorithms for solving multiobjective shortest path problems are described. A comparison of the effectiveness...
We propose new projection method for nonsmooth convex minimization problems. We present some method of subgradient selection, which is based on the so called residual selection model and is a generalization of the so called obtuse cone model. We also present numerical results for some test problems and compare these results with some other convex nonsmooth minimization methods. The numerical results show that the presented selection strategies ensure long steps and lead to an essential acceleration...
Using recent results on measure theory and algebraic geometry, we show how semidefinite programming can be used to construct invariant measures of one-dimensional discrete dynamical systems (iterated maps on a real interval). In particular we show that both discrete measures (corresponding to finite cycles) and continuous measures (corresponding to chaotic behavior) can be recovered using standard software.
In this paper we will describe a new class of coloring problems, arising from military frequency assignment, where we want to minimize the number of distinct -uples of colors used to color a given set of -complete-subgraphs of a graph. We will propose two relaxations based on Semi-Definite Programming models for graph and hypergraph coloring, to approximate those (generally) NP-hard problems, as well as a generalization of the works of Karger et al. for hypergraph coloring, to find good feasible...
In this paper we will describe a new class of coloring
problems, arising from military frequency assignment, where we want to
minimize the number of distinct n-uples of colors used to color a given
set of n-complete-subgraphs of a graph.
We will propose two relaxations based on
Semi-Definite Programming models for graph and hypergraph
coloring, to approximate those (generally) NP-hard problems, as well as
a generalization of the works of Karger et al. for hypergraph coloring,
to find good feasible...
In this paper we analyze a known relaxation for the Sparsest Cut
problem based on positive semidefinite constraints, and we present a
branch and bound algorithm and heuristics based on this relaxation.
The relaxed formulation and the algorithms were tested on small and moderate
sized instances. It leads to values very close to the
optimum solution values. The exact algorithm could obtain solutions
for small and moderate sized instances, and the best heuristics
obtained optimum or near optimum...
In this paper we analyze a known relaxation for the Sparsest Cut
problem based on positive semidefinite constraints, and we present a
branch and bound algorithm and heuristics based on this relaxation.
The relaxed formulation and the algorithms were tested on small and moderate
sized instances. It leads to values very close to the
optimum solution values. The exact algorithm could obtain solutions
for small and moderate sized instances, and the best heuristics
obtained optimum or near optimum...
This paper studies semi-Markov control models with Borel state and control spaces, and unbounded cost functions, under the average cost criterion. Conditions are given for (i) the existence of a solution to the average cost optimality equation, and for (ii) the existence of strong optimal control policies. These conditions are illustrated with a semi-Markov replacement model.
This paper describes an analytical study of open two-node (tandem) network models with blocking and truncation. The study is based on semi-Markov process theory, and network models assume that multiple servers serve each queue. Tasks arrive at the tandem in a Poisson fashion at the rate λ, and the service times at the first and the second node are nonexponentially distributed with means sA and sB , respectively. Both nodes have buffers with finite capacities. In this type of network, if the second...
Semi–smooth Newton methods are analyzed for a class of variational inequalities in infinite dimensions. It is shown that they are equivalent to certain active set strategies. Global and local super-linear convergence are proved. To overcome the phenomenon of finite speed of propagation of discretized problems a penalty version is used as the basis for a continuation procedure to speed up convergence. The choice of the penalty parameter can be made on the basis of an estimate for the penalized...
Semi–smooth Newton methods are analyzed for a class of variational
inequalities in infinite dimensions.
It is shown that they are equivalent to certain active set strategies.
Global and local super-linear convergence are
proved. To overcome the phenomenon of finite speed of propagation of
discretized problems a penalty version
is used as the basis for a continuation procedure to speed up convergence.
The choice of the penalty parameter
can be made on the basis of an L∞ estimate
for the penalized...
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319