672. On two-valued nonsovereign strategy-proof voting rules

Department of Economics and Statistics,University of Siena

 

It is shown that a two-valued and nonsovereign voting rule is strategy-proof on any preference domain that includes all pro?les of total preorders with a unique maximum if and only if votes for noneligible feasible alternatives are only available to dummy voters. It follows that dummy-free two-valued nonsovereign strategy-proof voting rules with a suitably restricted ballot domain do exist and essentially correspond to dummy-free sovereign strategy-proof voting rules for binary outcome spaces or, equivalently, to ordered transversal pairs of order ?lters of the coalition poset, and are also coalitionally strategy-proof. Moreover, it turns out that two-valued nonsovereign strategy-proof voting rules with full ballot domain do not exist.

 

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