Gibbard-Satterthwaite theorem
= Gibbard-Satterthwaite theorem
{c}
{wiki=Gibbard–Satterthwaite_theorem}
With a finite set of at least three alternatives and unrestricted strict preference orders, every onto deterministic <strategyproof> <social choice function> is a <dictatorship in social choice>. Restricting to two alternatives or to a restricted preference domain removes essential hypotheses.