View article

The personnel scheduling problem basically involves deciding at which times and on which days (ie which shifts) each employee should work over a specific planning period. However, the personnel scheduling problem is actually a title for a group of very similar problems. There is no general personnel scheduling problem. Instead there is a group of problems with a common structure but which differ in their constraints and objectives. This creates an additional challenge in implementing a problem domain module for personnel scheduling. To overcome this we have designed a data file format for which each instance can select a combination of a objectives and constraints from a wide choice. We then implemented a software framework containing all the functions for these constraints and objectives. The framework also contains methods for parsing these data files, data structures which can be used by heuristic algorithms (such as neighbourhood searches) and libraries for visualisations of instances and solutions. As mentioned, there is a large and diverse collection of constraints and objectives that can appear in personnel scheduling problems. For example, in one problem there may be a constraint on the maximum number of hours a nurse can work in the planning period. In another problem though this constraint may be an objective. That is, the nurse is allowed to exceed a certain number of hours but the excess should be minimised. The objective may then also be given a priority (relative to other objectives) using a weight. To be able to handle all these variations yet at the same time minimise the complexity of the file format and the amount …