In a market with indivisibilities, Roth and Postlewaite (1977) show that the (weak) core can suffer from instability problems, in the sense that groups of individuals might upset the equilibrium by recontracting among themselves. By contrast, the strong core is stable. Following the seminal...

From a normative viewpoint, there is no compelling reason for preferring the weak core over the σtrong core, and vice versa. However, the situation changes significantly from an economic design perspective. Coalitions are irrelevant for implementing in weak core by rights structures, but they...