COST Action IC 1205 on Computational Social Choice : STSM Report

During this STSM, together with my host Prof. Edith Elkind, we initiated the study of the following social choice problem. There is a set of issues, a set of voters, and a set of candidates. Candidates approve or disapprove issues, whereas voters have cardinal valuations for the issues; the valuation of a voter for an issue indirectly implies whether the voter wants the issue to be approved or not. A committee consists of some fixed size subset of the candidates. An issue is approved by a committee only if the majority of the committee members approve it, otherwise it is disapproved. The utility of a voter can be defined in several ways. For example, it could be defined as the number of issues to which the voter agrees with the committee’s decision or it could be defined as the distance of the voter’s valuation from the decision in some metric space. The social welfare is defined as the total utility of the voters. The problem is to select the committee members so that the social welfare is maximized.