Personnel Task Scheduling Problem Library. The Shift Minimisation Personnel Task Scheduling Problem (SMPTSP) belongs to the set of personnel scheduling problems. It arises when a set of tasks, fixed in time, have to be assigned to a set of shifts so that overlapping tasks are not assigned to the same shift. Each shift is associated with a given subset of assignable tasks. The objective is to minimise the number of used shifts. Note that depending on the real-life context, shifts may refer either to workers or more generally to constrained resources.