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. Some hypermedia synchronization issues request the resolution of the minimum convex piecewise linear cost tension problem (CPLCT problem) on directed graphs that are close to two-terminal series-parallel graphs (TTSP-graphs), the so-called quasi-k series-parallel graphs (k-QSP graphs). An aggregation algorithm has already been introduced for the CPLCT problem on TTSP-graphs. We propose here a reconstruction...
. Based on a pair of primal-dual LP formulations of the shortest path tree problem, the first algorithmic approach to reoptimizing the shortest paths subject to changes in the edge weights was proposed by S. Pallottino and M.G. Scutellá in 2003. We shall here focus solely on their introductory sections, propose some simplifications of the models considered, and finally relate the resulting models...
. Based on the recent approach of Bertsimas and Sim (2004, 2003) to robust optimization in the presence of data uncertainty, we prove an easily computable and simple bound on the probability that the robust solution gives an objective function value worse than the robust objective function value, under the assumption that only cost coefficients are subject to uncertainty. We exploit the binary nature...
. Pattern recognition generally requires the description of objects in terms of a set of measurable features. The quality of features representing each object has a considerable bearing on the success of pattern classification. Generally, the feature selection and clustering analysis are processed separately and most clustering techniques consider all features with equal importance. This paper presents...
. This is a summary of the main results presented in the au-thor’s PhD thesis. This thesis was supervised by Arnaud Fréville, Xavier Gandibleux and Joaquín Rodriguez, and defended on 10 December 2003 at the University of Valenciennes (France). It is written in French and is available at http: //www3.inrets.fr/~delorme/Papiers/These/These.pdf. This work deals with a real-world planning problem in railroad...
. We survey the main results presented by the author in his PhD thesis, supervised by F. Malucelli, and defended on the 15th March 2003. The thesis is written in English and is available on the Web page http: //www.elet.polimi.it/upload/belotti/thesis.pdf.gz. We investigate three problems, arising in the field of Telecommunication, of networks design with survivability constraints, and solve them...
. This paper focuses on the solution of the optimal diversity management problem formulated as a p-Median problem. The problem is solved for very large scale real instances arising in the car industry and defined on a graph with several tens of thousands of nodes and with several millions of arcs. The particularity is that the graph can consist of several non connected components. This property is...
. In this paper we tackle an important point of combinatorial optimisation: that of complexity theory when dealing with the counting or enumeration of optimal solutions. Complexity theory has been initially designed for decision problems and evolved over the years, for instance, to tackle particular features in optimisation problems. It has also evolved, more or less recently, towards the complexity...
. In the Frequency Assignment Problem with Polarization (FAPP), a given set of links must each be assigned a frequency and a polarization, while respecting given radio-electric compatibility constraints defined on pairs of links. In this paper, we propose a tabu search algorithm for the FAPP. A specialized neighborhood is proposed for the problem. Other key features of the algorithm are an adaptive...
. We consider a robot-safety device system attended by two different repairmen. The twin-system is characterized by the natural feature of cold standby and an admissible risky state. Apart from tangible results obtained in the previous Literature, we introduce a Markov time called the recovery time of the system. In order to obtain the corresponding distribution, we employ a stochastic process endowed...
. We present the main results in the author’s Ph.D. thesis (Iori 2004), defended at the University of Bologna in April 2004 and supervised by S. Martello. The thesis is written in English and is available from the author upon request. It proposes exact and metaheuristic algorithms for solving some relevant combinatorial optimization problems, with particular emphasis on scheduling, two-dimensional...
. In this paper we propose a new rule for removal of population members. We tested the new approach for solving the Quadratic Assignment Problem with excellent results.
. This paper provides an introductory survey of a class of optimization problems known as bilevel programming. We motivate this class through a simple application, and then proceed with the general formulation of bilevel programs. We consider various cases (linear, linear-quadratic, nonlinear), describe their main properties and give an overview of solution approaches.
. The problem retained for the ROADEF’2001 international challenge was a Frequency Assignment Problem with polarization constraints (FAPP). This NP-hard problem was proposed by the CELAR of the French Department of Defense, within the context of the CALMA project. Twenty seven competitors took part to this contest, and we present in this paper the contribution of our team that allowed us to be selected...
. The paper addresses the open-shop scheduling problem with unit-time operations and nondecreasing symmetric objective function depending on job completion times. We construct two schedules, one being optimal for any symmetric convex function, the other one for any symmetric concave function. Both schedules are given by analytically defined formulas that determine in O(1) time for each operation the...
. We survey the main results of the PhD Thesis presented by the author in December 2003 at The Institut National Polytechnique de Grenoble. This work was supervised by Prof. Lionel Dupont and assistant professor Christophe Rapine. The thesis is written in French and is available at http: //gilco.inpg.fr. In this work, we present results on the problem of selection and scheduling of orders in a make...
. Upper bounds for the length of a longest (circuit) cycle without chords in a (directed) graph are given in terms of the rank of the adjacency matrix and in terms of its eigenvalues.
. This is a summary of the most important results presented in the author's PhD thesis (Wong 2004). This thesis, written in English, was defended on 14 June 2004 at the Katholieke Universiteit Leuven (Belgium) and supervised by Dirk Cattrysse and Dirk Van Oudheusden. A copy is available from the author upon request. It presents a number of modeling and solution approaches for investigating how the...
. In this paper, we give three polynomial algorithms which detect a kernel in comparability graphs relatively to an M-orientation, in permutation graphs and in P4-free graphs with a normal orientation.
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