Hugues Marchand

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A separation heuristic for mixed integer programs is presented that theoretically allows one to derive several families of “strong” valid inequalities for specific models and computationally gives results as good as or better than those obtained from several existing separation routines including flow cover and integer cover inequalities. The heuristic is(More)
Constraints arising in practice often contain many 0-1 variables and one or a small number of continuous variables. Existing knapsack separation routines cannot be used on such constraints. Here we study such constraint sets, and derive valid inequalities that can be used as cuts for such sets, as well for more general mixed 0-1 constraints. Specifically we(More)
We investigate the use of cutting planes for integer programs with general integer variables. We show how cutting planes arising from knapsack inequalities can be generated and lifted as in the case of 0{1 variables. We also explore the use of Gomory's mixed integer cuts. We address both theoretical and computational issues and show how to embed these(More)
A dynamic knapsack set is a natural generalization of the 0-1 knapsack set with a continuous variable studied recently. For dynamic knapsack sets a large family of facet-defining inequalities, called dynamic knapsack inequalities, are derived by fixing variables to one and then lifting. Surprisingly such inequalities have the simultaneous lifting property,(More)
This survey presents cutting planes that are useful or potentially useful in solving mixed integer programs. Valid inequalities for i) general integer programs, ii) problems with local structure such as knapsack constraints, and iii) problems with 0-1 coefficient matrices, such as set packing, are examined in turn. Finally the use of valid inequalities for(More)
A branch-and-cut mixed integer programming system, called bc − opt, is described, incorporating most of the valid inequalities that have been used or suggested for such systems, namely lifted 0-1 knapsack inequalities, 0-1 gub knapsack and integer knapsack inequalities, flowcover and continuous knapsack inequalities, path inequalities for fixed charge(More)
A partir d’un échantillon de génisses charolaises culardes et normales accouplées avec des taureaux charolais de chaque type, nous avons précisé l’incidence du caractère culard sur la croissance et la morphologie des femelles après sevrage, ainsi que les conséquences de l’hypertrophie musculaire sur les difficultés de parturition. Le caractère culard(More)
In this paper, we propose computational methods for the synthesis of controllers for discrete event systems modeled by polynomial dynamical systems over nite Galois eld. The control objectives are speciied as order relations to be checked and as minimization of a given cost function over the states through the trajectories of the system. The control(More)
We study the computational complexity of several decision and optimization control problems arising in partially observed discrete event systems. These problems are related to the state avoidance problem where one must compute a controller which prevents the system from accessing a set of bad states and which is maximal for a defined criterion, based on(More)
A separation heuristic for mixed integer programs is presented that theoretically allows one to derive several families of \strong" valid inequalities for speciic models and computationally gives results as good as or better than those obtained from several existing separation routines including ow cover and integer cover inequalities. The heuristic is(More)