Computers and Operations Research
Computers and Operations Research
A multi-start evolutionary local search for the two-echelon location routing problem
HM'10 Proceedings of the 7th international conference on Hybrid metaheuristics
Computers and Operations Research
Multi-start heuristics for the two-echelon vehicle routing problem
EvoCOP'11 Proceedings of the 11th European conference on Evolutionary computation in combinatorial optimization
Engineering Applications of Artificial Intelligence
Solving the two-stage capacitated facility location problem by the lagrangian heuristic
ICCL'12 Proceedings of the Third international conference on Computational Logistics
An integrated supply chain network design problem for bidirectional flows
Expert Systems with Applications: An International Journal
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We consider a multi-echelon location-distribution problem arising from an actual application in fast delivery service. We present and compare two formulations for this problem: an arc-based model and a path-based model. We show that the linear programming (LP) relaxation of the path-based model provides a better bound than the LP relaxation of the arc-based model. We also compare the so-called binary relaxations of the models, which are obtained by relaxing the integrality constraints for the general integer variables, but not for the 0-1 variables. We show that the binary relaxations of the two models always provide the same bound, but that the path-based binary relaxation appears preferable from a computational point of view, since it can be reformulated as an equivalent simple plant location problem (SPLP), for which several efficient algorithms exist. We also show that the LP relaxation of this SPLP reformulation provides a better bound than the LP relaxation of the path-based model.