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Mardi 15 Septembre
| Heure: |
12:30 - 13:30 |
| Lieu: |
Salle B107, bâtiment B, Université de Villetaneuse |
| Résumé: |
A branch-and-cut-and-price algorithm for the green vehicle routing problem with partial recharges and multiple technologies |
| Description: |
Alberto Ceselli
Abstract: We tackle a variation of the vehicle routing problem in which the transportation fleet is composed of electric vehicles with limited autonomy in need for recharge during the execution of their duties. Different technologies can be chosen at each station, offering different trade-off between recharge cost and time.
We present an algorithm exploiting column generation, cutting planes and branch-and-bound for the exact solution of the problem. The pricing phase requires elementary resource constrained shortest path problems to be solved, and is carried out with both heuristics and an exact dynamic programming routine. The cut separation phase is performed by running heuristics from the literature on a particular support graph.
Experiments on benchmark instances from the VRP literature reveal that our algorithm is effective in solving instances with up to thirty customers, nine recharge stations, five vehicles and three technologies to optimality. |
Mardi 6 Octobre
| Heure: |
12:30 - 13:30 |
| Lieu: |
Salle B107, bâtiment B, Université de Villetaneuse |
| Résumé: |
The Johnson-Lindenstrauss Lemma in Linear and Integer Feasibility |
| Description: |
Leo Liberti The Johnson-Lindenstrauss lemma allows dimension reduction on real vectors with low distortion on their pairwise Euclidean distances. This result is often used in algorithms such as $k$-means or $k$ nearest neighbours since they only use Euclidean distances, and has sometimes been used in optimization algorithms involving the minimization of Euclidean distances. In this paper we introduce a first attempt at using this lemma in the context of feasibility problems in linear and integer programming, which cannot be expressed only in function of Euclidean distances.
Leo Liberti, Vu Khac Ky, Pierre-Louis Poirion
CNRS LIX, Ecole Polytechnique, Palaiseau, France |
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