INDEPENDENT SOCIAL CHOICE CORRESPONDENCES

A fixed agenda social choice correspondence Phi on outcome set X maps each profile of individual preferences into a nonempty subset of X. If Phi satisfies an analogue of Arrow's independence of irrelevant alter natives condition, then either the range of Phi contains exactly two a lternatives, or else there is at most one individual whose preferences have any bearing on Phi. This is the case even if Phi is not defined for any proper subset of X.