A general impossibility result on strategy-proof social choice hyperfunctions

A social choice hyperfunction picks a non-empty set of alternatives at each admissible preference profile over sets of alternatives. We analyze the manipulability of social choice hyperfunctions. We identify a domain D-lambda of lexicographic orderings which exhibits an impossibility of the Gibbard-Satterthwaite type. Moreover, this impossibility is inherited by all well-known superdomains of D-lambda. As most of the standard extension axioms induce superdomains of D-lambda while social choice correspondences are particular social choice hyperfunctions, we are able to generalize many impossibility results in the literature. (C) 2008 Elsevier Inc. All rights reserved.