Scheduler – a system for staff planning

Scheduling of staff is an important area, both from an academic and industrial point of view. There has been a lot of attention to develop new and efficient methods and models. In this paper, we consider the problem that given a work-force demand, a set of working rules and regulations find schedules for staff members with individual skills and preferences. The planning horizon is typically one week to several months. The problem both constructs tasks and simultaneously allocates them to staff members. The purpose of this paper is not to develop new theoretical results. Instead it deals with novel applications of known approaches to real-world practice. We describe a general scheduling software called SCHEDULER that includes a number of important features. The model is based on an elastic set-partitioning model and as solution method we use a branch-and-price algorithm. As branching strategy we make use of constraint branching and the column generator is a nested constrained shortest path formulation. An important feature is that only legal schedules are generated and used within the model. The system also allows for task changes within shifts, a general description of legal restrictions, preferences and allowable times. The system is in use at a number of companies and we report on the usage at some companies. We also give some numerical results to illustrate the behavior of some important features.