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frTue, 13 Mar 2018 11:48:56 +0100https://cedric.cnam.fr/index.php/labo/membre/kedad--ss
https://cedric.cnam.fr/index.php/labo/membre/kedad--ss
Safia Kedad-SidhoumaTue, 13 Mar 2018 11:48:55 +0100OCJobhttps://cedric.cnam.fr/index.php/publis/article/view?id=4234
https://cedric.cnam.fr/index.php/publis/article/view?id=4234
Quantifying extinction probabilities of endangered species for phylogenetic conservation prioritization may not be as sensitive as might be fearedIn this study we are concerned with the general problem of choosing from a set of endangered species T a subset S of k species to protect as a priority. Here, the interest to protect the species of S is assessed by the resulting expected phylogenetic diversity (ePD) of the set T, a widely used criterion for measuring the expected amount of evolutionary history associated with T. We consider that the survival of the protected species is assured and, on the contrary, that there is a risk of extinction for the unprotected species. The problem is easy to solve by a greedy type method if the extinction probabilities of the unprotected species are known but these probabilities are generally not easy to quantify. We show in this note that the choice of the precise values attributed to the extinction probabilities—provided it respects the rank of imperilment of each species—is not as decisive as might be feared for the considered problem. The values of these probabilities have a clear impact on the selection of the species to be protected but a little impact on the resulting ePD. More precisely, if T 1 and T 2 are the two optimal subsets of species corresponding to two scenarios (two different sets of probabilities) the ePDs of T 1 and T 2, calculated with the probabilities of the first scenario—or with the probabilities of the second scenario—are not very different.Thu, 08 Mar 2018 10:14:55 +0100OCPaperhttps://cedric.cnam.fr/index.php/publis/article/view?id=4184
https://cedric.cnam.fr/index.php/publis/article/view?id=4184
Exact and approximation algorithms for some packing and covering problems in graphsThu, 15 Feb 2018 01:27:44 +0100OCPaperhttps://cedric.cnam.fr/index.php/publis/article/view?id=4178
https://cedric.cnam.fr/index.php/publis/article/view?id=4178
Global solution of mixed-integer polynomial optimization problems through quadratic reformulationRésolution de programmes polynomiaux par reformulation convexeTue, 13 Feb 2018 17:10:25 +0100OCPaperhttps://cedric.cnam.fr/index.php/publis/article/view?id=4177
https://cedric.cnam.fr/index.php/publis/article/view?id=4177
Résolution du problème de suites binaires avec faible autocorrélation a l’aide d’une reformulation quadratique convexeNous présentons un nouvel algorithme pour résoudre le problème des suites binaires a faible autocorrélation en utilisant la programmation semidéfinie positive.Tue, 13 Feb 2018 16:57:18 +0100OCPaperhttps://cedric.cnam.fr/index.php/publis/article/view?id=4176
https://cedric.cnam.fr/index.php/publis/article/view?id=4176
Global Optimization of binary polynomial programsDans cette présentation, nous introduisons une nouvelle méthode de résolution de programmes polynomiaux binaires non contraints. Cette méthode s'appuie sur une double reformulation, une première refomulation quadratique, et une reformulation quadratique convexe.Tue, 13 Feb 2018 16:53:22 +0100OCPaperhttps://163.173.228.40/index.php/publis/article/view?id=4175
https://163.173.228.40/index.php/publis/article/view?id=4175
Solve Optimal Power Flow through reformulationThe Optimal Power Flow (OPF) problem consists in finding the best way to produce and drive power from producers to consumers in an electrical transmission network. It can be modeled as a continuous non convex and quadratically constrained quadratic program (QCQP). Our purpose is to solve (OPF) to global optimality. To this end, we propose reformulating the problem and then solving it by a branch-and-bound algorithm. We are interested in finding the best reformulation in terms of maximizing the bound at the root node of the branch-and-bound tree. We demonstrate that such a reformulation can be built using the solution of a semi-definite program.Tue, 13 Feb 2018 16:51:07 +0100OCPaperhttps://163.173.228.40/index.php/publis/article/view?id=4174
https://163.173.228.40/index.php/publis/article/view?id=4174
Quadratic convex reformulation for partitioning problemsQuadratic convex reformulation is a general method to solve quadratic programs. We consider its specialization to partitioning-like problems, namely, quadratic assignment and k-way graph partitioning. We compare two reformulation families. In the first one, we rely on the space of the initial variables only and obtain compact reformulations. In the second family, we aim at getting tighter relaxation bounds by increasing the size of the reformulated problem. We illustrate through experiments.Tue, 13 Feb 2018 16:46:50 +0100OCPaperhttps://cedric.cnam.fr/index.php/publis/article/view?id=4172
https://cedric.cnam.fr/index.php/publis/article/view?id=4172
Daily River Flow Prediction Based on Two Phase Constructive Fuzzy Systems Modeling: A Case of Hydrological - Meteorological Measurements AsymmetryFri, 09 Feb 2018 15:48:07 +0100OCPaperhttps://cedric.cnam.fr/index.php/publis/article/view?id=4145
https://cedric.cnam.fr/index.php/publis/article/view?id=4145
Puzzle game about connectivity and biological corridorsLandscape fragmentation prevents some species from moving as they should. This fragmentation, mainly due to urbanization, agriculture and forest exploitation, is a major cause of biodiversity loss. One of the options commonly envisaged to remedy this fragmentation - restore some connectivity - is the development of biological corridors. These corridors are natural spaces, usually linear. They allow species to move between different areas that are natural habitats for them.The purpose of this game is to raise awareness in different audiences (such as teachers, children, parents) about issues related to one of the challenges of the 21st century, preservation of biodiversity, and more particularly about the notion of connectivity. The issue is approached in a playful way: determine in a hypothetical landscape the cheapest network of biological corridors linking a set of fragmented natural habitats. This game can also be used to discuss human activities likely to develop in unprotected areas and having a negative impact on the preservation of biodiversity.Wed, 03 Jan 2018 17:02:20 +0100OCPaperhttps://cedric.cnam.fr/index.php/publis/article/view?id=4137
https://cedric.cnam.fr/index.php/publis/article/view?id=4137
Reroute Backward to Better Break DeadlocksFri, 15 Dec 2017 11:19:55 +0100OCPaperhttps://cedric.cnam.fr/index.php/publis/article/view?id=4136
https://cedric.cnam.fr/index.php/publis/article/view?id=4136
Scalable request routing for VR-Ready CDNsFri, 15 Dec 2017 11:15:38 +0100OCPaperhttps://cedric.cnam.fr/index.php/publis/article/view?id=4135
https://cedric.cnam.fr/index.php/publis/article/view?id=4135
Complexity and inapproximability results for the Power Edge Set problemFri, 15 Dec 2017 11:01:57 +0100OCPaperhttps://cedric.cnam.fr/index.php/publis/article/view?id=4113
https://cedric.cnam.fr/index.php/publis/article/view?id=4113
Equipe Optimisation Combinatoire Rapport d'activité 2012-juin 2017Rapport remis en vue de l'expertise HCERES du laboratoire CEDRIC du CNAM.Thu, 26 Oct 2017 15:32:03 +0200OCPaperhttps://cedric.cnam.fr/index.php/labo/membre/houdayer
https://cedric.cnam.fr/index.php/labo/membre/houdayer
Antoine HoudayeraSat, 14 Oct 2017 10:21:40 +0200OCJobhttps://cedric.cnam.fr/index.php/publis/article/view?id=4086
https://cedric.cnam.fr/index.php/publis/article/view?id=4086
Informatiqueno abstract.Wed, 06 Sep 2017 11:11:29 +0200OCPaperhttps://cedric.cnam.fr/index.php/publis/article/view?id=4083
https://cedric.cnam.fr/index.php/publis/article/view?id=4083
Global solution of non-convex quadratically constrained quadratic programsThe class of mixed-integer quadratically constrained quadratic programs (QCQP) consists of minimizing a quadratic function under quadratic constraints where the variables could be integer or continuous. On a previous paper we introduced a method called MIQCR for solving QCQPs with the following restriction: all quadratic sub-functions of purely continuous variables are already convex. In this paper, we propose an extension of MIQCR which applies to any QCQP. Let be a QCQP. Our approach to solve is first to build an equivalent mixed-integer quadratic problem . This equivalent problem has a quadratic convex objective function, linear constraints, and additional variables y that are meant to satisfy the additional quadratic constraints , where x are the initial variables of problem . We then propose to solve by a branch-and-bound algorithm based on the relaxation of the additional quadratic constraints and of the integrality constraints. This type of branching is known as spatial branch-and-bound. Computational experiences are carried out on a total of 325 instances. The results show that the solution time of most of the considered instances is improved by our method in comparison with the recent implementation of QuadProgBB, and with the solvers Cplex, Couenne, Scip, BARON and GloMIQOMon, 04 Sep 2017 14:42:16 +0200OCPaperhttps://cedric.cnam.fr/index.php/publis/article/view?id=4081
https://cedric.cnam.fr/index.php/publis/article/view?id=4081
Random projection for linear programmingSun, 27 Aug 2017 20:34:15 +0200OCPaperhttps://cedric.cnam.fr/index.php/publis/article/view?id=4068
https://cedric.cnam.fr/index.php/publis/article/view?id=4068
Erratum to: "C. Bentz, M.-C. Costa, F. Roupin. Maximum integer multiflow and minimum multicut
problems in two-sided uniform grid graphs [Journal of Discrete Algorithms 5 (2007) 36-54]"Ce rapport est un erratum a l'article suivant : C. Bentz, M.-C. Costa, F. Roupin. Maximum integer multiflow and minimum multicut problems in two-sided uniform grid graphs [Journal of Discrete Algorithms 5 (2007) 36-54].
Mon, 03 Jul 2017 21:24:33 +0200OCPaperhttps://cedric.cnam.fr/index.php/publis/article/view?id=4052
https://cedric.cnam.fr/index.php/publis/article/view?id=4052
How to Take into Account Uncertainty in Species Extinction Probabilities for Phylogenetic Conservation PrioritizationIn this article we are concerned with the general problem of choosing from a set of taxa T a subset S to protect in order to try to contribute to halting biodiversity loss as efficiently as possible given limited resources. The protection of a taxon decreases its extinction probability and the impact of protecting the taxa of S is measured by the resulting expected phylogenetic diversity (ePD) of the set T. The primary challenge posed by this approach lies in determining the extinction probability of a taxon (protected or unprotected). To deal with this difficulty, the uncertainty about the extinction probabilities can be described through a set of possible scenarios, each corresponding to different extinction probabilities values for each taxon. We show how to determine an “optimal robust set” of taxa to protect, defined as the set of taxa that minimizes the maximum “regret”, i.e. the maximum relative gap, over all the scenarios, between 1) the ePD of T obtained by protecting the taxa of this set and 2) the ePD of T which would be produced by protecting the subset of taxa optimal for the considered scenario. In our experimental conditions covering one hundred cases, this gap is almost always less than 1%. Consequently, the ePD of T obtained by protecting the taxa of the optimal robust set is not far from the maximum ePD of T that could have been obtained if we had known the true scenario. In other words, a way of escaping (in large part, at least) from the uncertainty related to the extinction probabilities of the taxa consists of choosing to protect those belonging to the optimal robust set. We also compare the optimal robust set to other relevant subsets of T.
Tue, 13 Jun 2017 07:57:37 +0200OCPaperhttp://cedric.cnam.fr/index.php/publis/article/view?id=4044
http://cedric.cnam.fr/index.php/publis/article/view?id=4044
Reconstruction of Nearly Convex Colored ImagesThis paper studies the problem of reconstructing hv-convex images with a small
number of discrete colors from two projections for each color in horizontal and vertical
directions. A new integer programming based method is proposed to reconstruct nearly hv-
convex colored images. Firstly, we model the reconstruction problem by a quadratic binary
program. Secondly, we linearize the program into two linear binary programs. Thirdly, we
solve the continuous relaxation of these programs by using IBM ILOG Cplex.Mon, 05 Jun 2017 10:43:16 +0200OCPaperhttp://cedric.cnam.fr/index.php/publis/article/view?id=4043
http://cedric.cnam.fr/index.php/publis/article/view?id=4043
A Greedy Algorithm for Reconstructing Binary Matrices with Adjacent 1sThis paper deals with the reconstruction of special cases of binary matrices with
adjacent 1s. Each element is horizontally adjacent to at least another element. The
projections are the number of elements on each row and column. We give a greedy
polynomial time algorithm to reconstruct such matrices when satisfying only the vertical
projection. We show also that the reconstruction is NP-complete when fixing the number of
sequence of length two and three per row and column.Mon, 05 Jun 2017 10:40:51 +0200OCPaperhttps://cedric.cnam.fr/index.php/publis/article/view?id=4039
https://cedric.cnam.fr/index.php/publis/article/view?id=4039
Daily River Flow Prediction Coupled with Data Processing Techniques: A Comparative Study between Constructive Fuzzy Systems and Autoregressive ModelsDaily river flow forecast is an essential step for real-time hydro-power reservoir operation. The purpose of the flow forecast is to assist in the decision-making process in order to ensure optimal
and reliable operational policy. The paper presents, in a region where meteorological and hydrological data are insufficient, inaccessible and sometimes unreliable, a data-driven model based on Constructive Fuzzy Systems. The model is capable of exploiting the available data with high prediction efficiency was compared to an Autoregressive method. A case study was applied to Litani River in the Bekaa Valley - Lebanon using 4 years of rainfall, temperature, and river flow daily measurements. A reference Auto-Regressive (AR) model, a classical Constructive Fuzzy System Modeling (C-FSM) and the Constructive Fuzzy System Modeling coupled with Moving Average (C-FSM_MA) filter are trained. Upon testing, the last two models have shown primarily competitive performance and accuracy with the ability to preserve the day-to-day variability up to 12 days ahead. In fact, for the longest lead period, the models AR, C-FSM and C-FSM_MA were able of explaining respectively 75%, 79.5% and 84.3% of the actual river flow variation. These results indicate that Moving Average (MA) filter provides a supportive pre-processing tool in the process of streamflow forecasting.
Fri, 02 Jun 2017 18:08:28 +0200OCPaperhttps://cedric.cnam.fr/index.php/publis/article/view?id=4032
https://cedric.cnam.fr/index.php/publis/article/view?id=4032
Reducing the Chromatic Number by Vertex or Edge DeletionsA vertex or edge in a graph is critical if its deletion reduces the chromatic number of the graph by~1.
A graph is vertex-critical if every vertex is critical and edge-critical if every edge is critical.
To increase our understanding of the graph coloring problem, vertex-critical and edge-critical graphs have been studied intensively. We consider the problems of testing whether a graph has a critical vertex or edge, respectively.
We give a complete classification of the complexity of both problems for $H$-free graphs, that is, graphs with no induced subgraph isomorphic to $H$. Moreover, we show that an edge is critical if and only if its contraction reduces the chromatic number by~1.
Hence, we obtain the same classification for the problem of testing if a graph has an edge whose contraction reduces
the chromatic number by~1.
As a consequence of our results, we are also able to complete the complexity classification of the more general vertex deletion and edge contraction blocker problems for $H$-free graphs
when the graph parameter is the chromatic number.
Tue, 30 May 2017 09:53:21 +0200OCPaperhttps://cedric.cnam.fr/index.php/publis/article/view?id=3967
https://cedric.cnam.fr/index.php/publis/article/view?id=3967
Résumé: Logiciel de résolution Logiciel qui résout des programmes quadratiques généraux ayant des variables entières ou réelle et des fonctions quadratiques non convexes. http://cedric.cnam.fr/~lamberta/smiqp/smiqp.php Mises a jour régulières qui suivent les publications [BEL12,BEL13,BEL14,BEL16,BEL16a]. Licence libre.
SMIQP (Solution of Mixed Integer Quadratic Programs). version 2Logiciel de résolution Logiciel qui résout des programmes quadratiques généraux ayant des variables entières ou réelle et des fonctions quadratiques non convexes. http://cedric.cnam.fr/~lamberta/smiqp/smiqp.php
Publications liées [BEL13,BEL14,BEL16,BEL16a]. Licence libre.Wed, 10 May 2017 10:38:37 +0200OCPaperhttps://cedric.cnam.fr/index.php/publis/article/view?id=3966
https://cedric.cnam.fr/index.php/publis/article/view?id=3966
SMIQP (Solution of Mixed Integer Quadratic Programs)Logiciel de résolution Logiciel qui résout des programmes quadratiques généraux ayant des variables entières ou réelle et des fonctions quadratiques non convexes.
http://cedric.cnam.fr/~lamberta/smiqp/smiqp.php
Mises a jour régulières qui suivent les publications [BEL12,BEL13,BEL14,BEL16,BEL16a]. Licence libre.Wed, 10 May 2017 09:54:36 +0200OCPaperhttps://cedric.cnam.fr/index.php/publis/article/view?id=3964
https://cedric.cnam.fr/index.php/publis/article/view?id=3964
Logiciel "Integer Ray Method"Logiciel pour résoudre des programmes de type « génération de colonnes » comme par exemple l'Arc-Routing et le Cutting-Stock (http://cedric.cnam.fr/~porumbed/irm/)Tue, 09 May 2017 15:59:42 +0200OCPaperhttps://cedric.cnam.fr/index.php/publis/article/view?id=3963
https://cedric.cnam.fr/index.php/publis/article/view?id=3963
Bilevel model for adaptive network flow problemTue, 09 May 2017 11:07:21 +0200OCPaperhttps://cedric.cnam.fr/index.php/publis/article/view?id=3962
https://cedric.cnam.fr/index.php/publis/article/view?id=3962
The power edge set problemThe automated real time control of an electrical network is achieved through the estimation of its state using phasor measurement units. Given an undirected graph representing the network, we study the problem of finding the minimum number of phasor measurement units to place on the edges such that the graph is fully observed. This problem is also known as the Power Edge Set problem, a variant of the Power Dominating Set problem. It is naturally modeled using an iteration-indexed binary linear program, whose size turns out to be too large for practical purposes. We use a fixed-point argument to remove the iteration indices and obtain a more compact bilevel formulation. We then reformulate the latter to a single-level mixed-integer linear program, which performs better than the natural formulation. Lastly, we provide an algorithm that solves the bilevel program directly and much faster than a commercial solver can solve the previous models. We also discuss robust variants and extensions of the problemTue, 09 May 2017 10:59:17 +0200OCPaperhttps://cedric.cnam.fr/index.php/publis/article/view?id=3961
https://cedric.cnam.fr/index.php/publis/article/view?id=3961
Solving LP using random projectionsA celebrated result of Johnson and Lindenstrauss asserts that, in high enough dimensional spaces, Euclidean distances defined by a finite set of points are approximately preserved when these points are projected to a certain lower dimensional space. We show that the distance from a point to a convex set is another approximate invariant, and leverage this result to approximately solve linear programs with a logarithmic number of rows.Tue, 09 May 2017 10:56:29 +0200OCPaper