E-commerce warehousing and some new results on picker routing


In the wake of ever-increasing e-commerce sales, warehouses have evolved to technology-enriched, mission-critical fulfillment factories. This talk reviews suitable e-commerce warehouse structures such as scattered storage and robot-assisted order picking and investigates the routing problems that are to be solved within these novel warehouses. In the very core of traditional picker-to-parts warehouses is the classical picker routing problem, which equals the traveling salesman problem (TSP) but is well-known to be efficiently solvable in the parallel-aisle structure of warehouses. New warehouses require the solution of other well-known extended routing problems, such as the clustered TSP, the generalized TSP, and the prize collecting TSP. All these routing problems are well-known to be strongly NP-hard for general graphs. This talk shows how the warehouse structure impacts this complexity status and how the parallel-aisle structure of warehouses can be exploited to improve the efficiency of routing algorithms.


After some industry practice at IBM Global Services, Nils joined the Friedrich Schiller University in Jena (Germany), where he became a full professor for operations management. His main research interests are in the fields of facility logistics, warehousing, transportation, and automobile production. To solve industry problems in these areas, Nils applies mathematical modelling and combinatorial optimization techniques, always based on a thorough analysis of computational complexity. He has published over 150 research papers in many of the top optimization and logistics journals. Among others he is a member of the editorial boards of Transportation Science and EJOR.