The varied landscape of consistent approval-based multi-winner rules

6^th June 2017, 13:00 George Holt H223
Dr. Martin Lackner
University of Oxford
Department of Computer Science
Wolfson Building, Parks Road, Oxford

Abstract

The goal of this talk is to provide an overview of recent work on approval-based multi-winner rules. Approval-based multi-winner rules are voting rules that select a fixed-size group of candidates based on approval ballots. Such rules are applicable to a wide range of scenarios concerning group decision making and consequently may aim for widely diverging objectives.

In this talk, I introduce the class of counting rules and discuss axiomatic characterizations of rules in this class. In particular, I present axiomatic characterizations of three import consistent multi-winner rules: Proportional Approval Voting, Multi-Winner Approval Voting and Approval Chamberlin--Courant.
These results demonstrate the variety of multi-winner rules and the different, orthogonal goals that multi-winner voting rules may pursue.

This talk is based on joint work with Piotr Skowron.