Alternative MIP formulations for an integrated shift scheduling and task assignment problem

A problem of personnel scheduling in a multiskilled environment is addressed. This problem is treated in an integrated manner, modelling shift scheduling and task assignment as one problem. Additionally, the integrated approach allows also to better model intraday breaks and days-off scheduling. Alternative MIP formulations are presented which lead to optimal shift schedulings and task assignments. Improved models are obtained by deriving new block indexed and position indexed variables. Computational results show the improvement obtained by extended formulations.