Overlapping Multiple Assignments

This paper studies an allocation problem with multiple assignments, indivisible objects, no endowments and no monetary transfers, where a single object may be assigned to several agents as long as the set of agents assigned the object satisfy a compatibility constraint. It is shown that, on the domain of complete, transitive and strict preferences, group-sorting sequential dictatorships are fully characterized by four different combinations of coalitional strategyproofness, strategyproofness, Pareto efficiency, non-bossiness, group-monotonicity and group-invariance. It is also demonstrated that the characterization in Pápai (2001) of sequential dictatorships for the case where assignments are not allowed to overlap is contained in the main result.