Generalizedcoverage:Newdevelopmentsincoveringlocationmodels

The goalofthepaperistoprovideanoverviewofthefollowingclassesofmodels: Gradualcovermodels:Thesemodelsseektorelaxthe‘‘allornothing’’assumptionbyreplacingit with ageneralcoveragefunctionwhichrepresentstheproportionofdemandcoveredatacertain distance fromthefacility. The cooperativecovermodel:Thisrecentlydevelopedgeneralizationisdesignedtoreplacethe ‘‘individualcoverage’’assumptionwithamechanismwhereallfacilitiescontributetothecoverageof each demandpoint.Thisisaccomplishedbyviewingcoverageasthetransmissionofa‘‘signal’’bythe facilities.Thesignaltransmittedbyeachfacilitydissipateswithdistance.However,thesignalreceived by eachdemandpointistheaggregationofthetransmissionsfromallthefacilities.Ifthesignal strengthatthedemandpointexceedsacertainthreshold,thepointiscovered,otherwiseitisnot. Variableradiusmodel:Thismodelisprimarilydesignedtorelaxthe‘‘fixedcoverageradius’’ assumption,makingthecoverageradiusanendogenouslydeterminedfunctionofthefacilitycost.Thus, insteadofhavingtolocateacertainpre-determinednumberoffacilities,thedecision-makerhasa certainbudgetthatcanbeusedtoconstructfacilitiesofdifferenttypes,withthemoreexpensive facilitieshavinglargercoverageradius.