An exact approach for the personnel task rescheduling problem with task retiming

In this paper, we study the personnel task rescheduling problem with task retiming. We assume a baseline personnel task schedule that is subject to different types of disruptions, occurring on a daily basis. This operational uncertainty is the result of three sources of variability, i.e. uncertainty of demand, uncertainty of capacity and uncertainty of arrival, which may render the baseline schedule infeasible. Therefore, the rescheduling of the originally constructed personnel schedule is necessary to compose an operational schedule. We propose a dedicated branch-and-price procedure to recover the personnel task schedule, which considers a wide range of recovery mechanisms to reassign the tasks to workers, allowing the retiming of tasks, to restore the feasibility. Different computational experiments are conducted to show the performance of the proposed branch-and-price thriving on different speed-up techniques and optimisation principles. We benchmark the proposed algorithm with other optimisation procedures and show the contribution of the algorithm design choices.