On the Neutrality of Flowshop Scheduling Fitness Landscapes

Solving efficiently complex problems using metaheuristics, and in particular local searches, requires incorporating knowledge about the problem to solve. In this paper, the permutation flowshop problem is studied. It is well known that in such problems, several solutions may have the same fitness value. As this neutrality property is an important one, it should be taken into account during the design of optimization methods. Then in the context of the permutation flowshop, a deep landscape analysis focused on the neutrality property is driven and propositions on the way to use this neutrality to guide efficiently the search are given.Comment: Learning and Intelligent OptimizatioN Conference (LION 5), Rome : Italy (2011

Ant Colonies for the Quadratic Assignment Problem

This paper presents HAS-QAP, a hybrid ant colony system coupled with a local search, applied to the quadratic assignment problem. HAS-QAP uses pheromone trail information to perform modifications on QAP solutions, unlike more traditional ant systems that use pheromone trail information to construct complete solutions. HAS-QAP is analysed and compared with some of the best heuristics available for the QAP: two versions of tabu search, namely, robust and reactive tabu search, hybrid genetic algorithm, and a simulated annealing method. Experimental results show that HAS QAP and the hybrid genetic algorithm perform best on real world, irregular and structured problems due to their ability to find the structure of good solutions, while HAS-QAP performance is less competitive on random, regular and unstructured problems.info:eu-repo/semantics/publishe

A tabu search heuristic for the heterogeneous fleet vehicle routing problem

The Heterogeneous Fleet Vehicle Routing Problem (HVRP) is a variant of the classical Vehicle Routing Problem in which customers are served by a heterogeneous fleet of vehicles with various capacities, fixed costs, and variable costs. This article describes a tabu search heuristic for the HVRP. On a set of benchmark instances, it consistently produces high-quality solutions, including several new best-known solutions. Scope and purpose. In distribution management, it is often necessary to determine a combination of least cost vehicle routes through a set of geographically scattered customers, subject to side constraints. The case most frequently studied is where all vehicles are identical. This article proposes a solution methodology for the case where the vehicle fleet is heterogeneous. It describes an efficient tabu search heuristic capable of producing high-quality solutions on a series of benchmark test problems.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Integration of Social Concerns in Collaborative Logistics and Transportation Networks

Part 21: Mobility and LogisticsInternational audienceFreight transport optimization, long based solely on an economic approach, happen today through the integration of environmental and/or social concerns, in line with the objectives of sustainable development. In the case of Small and Very Small Enterprises, these objectives cannot be reached individually, and these companies have to join their efforts to find collective solutions. Therefore, the Fleet Size and Mix Vehicle Routing Problem (FSMVRP) was adapted to take into account social objectives, and results are compared to Vehicle Routing Problem with homogeneous fleet. An exact mathematical formulation of the extended problem was developed. Computational experiments for the problem formulation are performed using CPLEX and give a solution of a small instance to illustrate the problem. The model is tested on a case study of optimal parcel pickup, from many manufacturers to a common depot in the agri-food sector