Selecting Interlacing Committees

Polarization is a major concern for a well-functioning society. Often, mass polarization of a society is driven by polarizing political representation, even when the latter is easily preventable. The existing computational social choice methods for the task of committee selection are not designed to address this issue. We enrich the standard approach to committee selection by defining two quantitative measures that evaluate how well a given committee interconnects the voters. Maximizing these measures aims at avoiding polarizing committees. While the corresponding maximization problems are NP-complete in general, we obtain efficient algorithms for profiles in the voter-candidate interval domain. Moreover, we analyze the compatibility of our goals with other representation objectives, such as excellence, diversity, and proportionality. We identify tradeoffs between approximation guarantees, and describe algorithms that achieve simultaneous constant-factor approximations.

Authors

• Chris Dong Technical University of Munich
• Martin Bullinger University of Oxford
• Tomasz Was University of Oxford
• Larry Birnbaum
• Edith Elkind Northwestern University, USA

Keywords

• Computational Social Choice
• Approval-Based Committee Voting
• Polarization