An openvehicleroutingproblemmetaheuristicforexaminingwidesolution neighborhoods

This paperexaminesapracticaltransportationmodelknownastheopenvehicleroutingproblem(OVRP). OVRP aimsatdesigningtheminimumcostsetofroutesoriginatingfromacentraldepotforsatisfying customer demand.Vehiclesdonotneedtoreturntothedepotaftercompletingtheirdeliveryservices.In methodological terms,weproposeaninnovativelocalsearchmetaheuristicwhichexamineswidesolution neighborhoods. Toexplorethesewideneighborhoodswithinreasonablecomputationaleffort,localsearch moves arestaticallyencodedintostaticmovedescriptor(SMD)entities.Whenalocalsearchoperatoris applied tothecandidatesolution,onlyalimitedsolutionpartismodified.Therefore,toexplorethenext neighborhood onlythetentativemovesthatrefertothisaffectedsolutionparthavetobere-evaluated,or in otherwords,onlyasubsetoftheSMDinstanceshastobeupdated,accordingtothemodifiedsolution state. TheconductedsearchisefficientlyperformedbystoringtheSMDentitiesinFibonacciheaps,which are specialpriorityqueuestructuresofferingfastminimumretrievals,insertionsanddeletions.Todiversify the search,weemployatabuschemeandapenalizationstrategy,bothcompatiblewiththeSMDdesign. The proposedmetaheuristicwastestedonwell-knownOVRPinstances,fortwoobjectiveconfigurations. The firstoneprimarilyaimsatminimizingthenumberofroutesandsecondarilyminimizingtherouting cost, whereasthesecondoneonlyaimsatminimizingthecostofthegeneratedrouteset.Forboth configurations, itmanagedtoproducefineresultsimprovingseveralpreviouslybest-knownsolutions.