fr Fri, 08 Jul 2011 15:44:06 +0200 http://cedric.cnam.fr/index.php/publis/article/view?id=2138 http://cedric.cnam.fr/index.php/publis/article/view?id=2138 Mon, 04 Jul 2011 16:23:21 +0200 OC Paper http://cedric.cnam.fr/index.php/publis/article/view?id=1837 http://cedric.cnam.fr/index.php/publis/article/view?id=1837 Mon, 04 Jul 2011 15:01:37 +0200 OC Paper http://cedric.cnam.fr/index.php/publis/article/view?id=1887 http://cedric.cnam.fr/index.php/publis/article/view?id=1887 We consider a set V of elements and an optimization problem on V : the search for a maximum (or minimum) cardinality subset of V verifying a given property P. A d-transversal is a subset of V which intersects any optimum solution in at least d elements while a d-blocker is a subset of V whose removal deteriorates the value of an optimum solution by at least d. We present some general characteristics of these problems, we review some situations which have been studied (matchings, s . t paths and s . t cuts in graphs) and we study d-transversals and d-blockers for new problems as stable sets or vertex covers in bipartite graphs. Keywords: transversal, blocker, cover, bipartite graph, matching, s. t path, s . t cut, stable set, bilevel programming. Mon, 04 Jul 2011 15:01:20 +0200 OC Paper http://cedric.cnam.fr/index.php/publis/article/view?id=2036 http://cedric.cnam.fr/index.php/publis/article/view?id=2036 We study the dual power management problem in wireless sensor networks. Given a wireless sensor network with two possible power levels (heigh and low) for each sensor, the problem consists in minimizing the number of sensors assigned heigh power while ensuring the connectivity of the network. We formulate the problem by a binary integer programming model to minimize the total power consumption. Since the problem is NP-complete, we provide an iterative approximation based on iterative methods in combinatorial optimization. We solve the separation subproblem as a minimum spanning tree . Mon, 04 Jul 2011 15:01:02 +0200 OC Paper