Strategy-proof Sharing

We consider the problem of sharing a good, where agents prefer more to less. In this environment, we prove that a sharing rule satisfies strategy-proofness if and only if it has the quasi-constancy property:no one changes her own share by changing her announcements. Next,by constructing a system of linear equations, we provide a way to find every strategy-proof sharing rule, and identify a necessary and sufficient condition for the existence of a non-constant, strategy-proof sharing rule. Finally, we show that it is only the equal-sharing rule that satisfies strategy-proofness and symmetry.