Publications

The container relocation problem (CRP) is concerned with finding a sequence of moves of containers that minimizes the number of relocations needed to retrieve all containers, while respecting a given order of retrieval. However, the assumption of knowing the full retrieval order of containers is particularly unrealistic in real operations. This paper studies the stochastic CRP, which relaxes this assumption. A new multistage stochastic model, called the batch model, is introduced, motivated, and compared with an existing model (the online model). The two main contributions are an optimal algorithm called Pruning-Best-First-Search (PBFS) and a randomized approximate algorithm called PBFS-Approximate with a bounded average error. Both algorithms, applicable in the batch and online models, are based on a new family of lower bounds for which we show some theoretical properties. Moreover, we introduce two new heuristics outperforming the best existing heuristics. Algorithms, bounds, and heuristics are tested in an extensive computational section. Finally, based on strong computational evidence, we conjecture the optimality of the “leveling” heuristic in a special “no information” case, where, at any retrieval stage, any of the remaining containers is equally likely to be retrieved next.

Three prominent research programmes in cognitive psychology would benefit from a stronger engagement with the cultural context of cognition: studies of poverty focused on scarcity and cognitive bandwidth, studies of dual-process morality and stud- ies of biases using the implicit association test. We address some limitations of these programmes and suggest research strat- egies for moving beyond an exclusive focus on cognition. Research on poverty using the cognitive bandwidth approach would benefit from considering the cultural schemas that influence how people perceive and prioritize needs. Dual-process morality researchers could explain variation by analysing cultural repertoires that structure moral choices. Research using the implicit association test can better explain implicit attitudes by addressing the variability in cultural schemas that undergird biases. We identify how these research programmes can deepen the causal understanding of human attitudes and behaviours by address- ing the interaction between internal cognition and supra-individual cultural repertoires.