A heuristic rule for relocating blocks

One of the most important objectives of the storage and pickup operations in block stacking systems is to minimize the number of relocations during the pickup operation. This study suggests two methods for determining the locations of relocated blocks. First, a branch-and-bound (B&B) algorithm is suggested. Next, a decision rule is proposed by using an estimator for an expected number of additional relocations for a stack. The performance of the decision rule was compared with that of the B&B algorithm.