Tabu Search Foundations: Longer Term Memory

In some applications, the short term TS memory components are sufficient to produce very high quality solutions. However, in general, TS becomes significantly stronger by including longer term memory and its associated strategies. In the longer term TS strategies, the modified neighborhood produced by tabu search may contain solutions not in the original one, generally consisting of selected elite solutions (high quality local optima) encountered at various points in the solution process. Such elite solutions typically are identified as elements of a regional cluster in intensification strategies, and as elements of different clusters in diversification strategies. In addition, elite solution components, in contrast to the solutions themselves, are included among the elements that can be retained and integrated to provide inputs to the search process.