Eliciting a Suitable Voting Rule via Examples

We address the problem of specifying a voting rule by means of a series of examples. Each example consists of the answer to a simple question: how should the rule rank two alternatives, given the positions at which each voter ranks the two alternatives? To be able to formalise this elicitation problem, we develop a novel variant of classical social choice theory in terms of associations of alternatives with vectors of ranks rather than the common associations of voters with preference orders. We then define and study a class of voting rules suited for elicitation using such answers. Finally, we propose and experimentally evaluate several elicitation strategies for arriving at a good approximation of the target rule with a reasonable number of queries.