Edith Elkind
2015 - 2020 • Starting Grant
Algorithms for complex collective decisions on structured domains
Social choice theory deals with the ubiquitous need in social and professional situations to aggregate individual preferences to determine a collective choice. As with virtually every complex field, the use of computational science can help us understand and predict the process of social choice determination. Computational social choice is the field of study concerned with just this. The ACCORD project will bridge the gap between the theory and practice of collective decision making. The team will develop new, open-source computational tools and methodologies to characterise and predict collective decision making in settings where each member has preferences regarding a finite set of alternative choices.
Result
The aim of the project was to substantially advance the field of computational social choice by developing new tools and methodologies that can be used for making complex group decisions in rich and structured environments. The team considered settings where each member of a decision-making body has preferences over a finite set of alternatives, and the goal was to synthesise a collective preference over a set of alternatives with a predefined structure. The team formulated desiderata that apply to such preference aggregation procedures, designed procedures to satisfy these desiderata, and developed algorithms for computing them. To lower the cognitive burden on the decision-makers, they extended the procedures to accept partial rankings as inputs. The team also provided open-source software implementations of their procedures and reached out to potential users to obtain feedback on their practical applicability.
Impact
Defining and exploring preferences that are single-peaked on a circle and identifying tractable subdomains of the domain of preferences that are single-peaked on a line. The axioms for multiwinner rules that have been identified in the course of the research are equally important, as they offer criteria for choosing decision-making rules.