Committee Selection with Attribute Level Preferences
This addresses the problem of selecting more representative committees in voting systems for stakeholders like political or organizational groups, though it is incremental as it builds on existing attribute-based preference work.
The paper tackles the committee selection problem by allowing voters to approve candidate attributes rather than candidates, aiming to improve representation and reduce manipulation. It formally defines new representation properties, shows existing rules fail them, and proves that achieving compound justified representation and maximizing approval scores are NP-complete.
We consider the problem of committee selection from a fixed set of candidates where each candidate has multiple quantifiable attributes. To select the best possible committee, instead of voting for a candidate, a voter is allowed to approve the preferred attributes of a given candidate. Though attribute based preference is addressed in several contexts, committee selection problem with attribute approval of voters has not been attempted earlier. A committee formed on attribute preferences is more likely to be a better representative of the qualities desired by the voters and is less likely to be susceptible to collusion or manipulation. In this work, we provide a formal study of the different aspects of this problem and define properties of weak unanimity, strong unanimity, simple justified representations and compound justified representation, that are required to be satisfied by the selected committee. We show that none of the existing vote/approval aggregation rules satisfy these new properties for attribute aggregation. We describe a greedy approach for attribute aggregation that satisfies the first three properties, but not the fourth, i.e., compound justified representation, which we prove to be NP-complete. Furthermore, we prove that finding a committee with justified representation and the highest approval voting score is NP-complete.