Zheng, S.; Wang, A.; Mohmand, Y.T., and He, Y., 2017. Path optimum algorithm for container relocation problems in port terminals worldwide.

The container relocation problem (CRP) is concerned with emptying a cluster of identical containers stacked in one bay where every container is given a fixed extractive sequence with the fewest number of relocations. Such a typical problem has been examined in this paper. This research differs from previous studies in the following aspects: First, the retrieval paths of the CRP is proposed and its nondeterministic polynomial-time-hardness has been proved. Moreover, a mathematical model is presented that can provide the theoretical basis for the current research. Since the feasible retrieval paths are numerous, heuristic rules are presented to effectively reduce the resolution space. In addition, a new path optimum algorithm (POA) based upon heuristics is proposed to find the optimal solution for any-scale instances in a shorter central processing unit run time. Numerical experiments and comparisons with the other algorithms from the literature show the superiority, high efficiency, robustness, and accuracy of this algorithm. As competition among coastal and inland container ports has become fierce, POA can be used to increase port handling efficiency and facilitate the decision making regarding container port infrastructure planning, and contribute to coastal research worldwide.