Hyper-heuristics for personnel scheduling domains

In real-life applications problems can frequently change or require small adaptations. Manually creating and tuning algorithms for different problem domains or different versions of a problem can be cumbersome and time-consuming. In this paper we consider several important problems with high practical relevance, which are Rotating Workforce Scheduling, Minimum Shift Design, and Bus Driver Scheduling. Instead of designing very specific solution methods, we propose to use the more general approach based on hyper-heuristics which take a set of simpler lowlevel heuristics and combine them to automatically create a fitting heuristic for the problem at hand. This paper presents a major study on applying hyper-heuristics to these domains, which contributes in four different ways: First, it defines new low-level heuristics for these scheduling domains, allowing to apply hyper-heuristics to them for the first time. Second, it provides a comparison of several state-of-the-art hyper-heuristics on those domains. Third, new best solutions for several instances of the different problem domains are found. Finally, a detailed investigation of the use of low-level heuristics by the hyper-heuristics gives insights in the way hyper-heuristics apply to different domains and the importance of different low-level heuristics. The results show that hyper-heuristics are able to perform well even on very complex practical problem domains in the area of scheduling and, while being more general and requiring less problem-specific adaptation, can in several cases compete with specialized algorithms for the specific problems. Several hyper-heuristics with very good performance across different real-life domains are identified. They can efficiently select low-level heuristics to apply for each domain, but for repeated application they benefit from evaluating and selecting the most useful subset of these heuristics. These results help to improve industrial systems in use for solving different scheduling scenarios by allowing faster and easier adaptation to new problem variants.