Strategic Cost Selection in Participatory Budgeting

Piotr Faliszewski, Łukasz Janeczko, Andrzej Kaczmarczyk, Grzegorz Lisowski, Piotr Skowron, Stanisław Szufa, Mateusz Szwagierczak

AGH University· University of Chicago· University of Groningen· University of Warsaw· CNRS· Université Paris Dauphine PSL

Participatory Budgeting Social Choice Game Theory Equilibria

⋅ NeurIPS ⋅ OpenReview

Abstract

We study strategic behavior of project proposers in the context of approval-basedparticipatory budgeting (PB). In our model we assume that the votes are fixed andknown and the proposers want to set as high project prices as possible, providedthat their projects get selected and the prices are not below the minimum costs oftheir delivery.

We study the existence of pure Nash equilibria (NE) in such games,focusing on the AV/Cost, Phragmen, and Method of Equal Shares rules.

We alsoprovide an experimental study of cost selection on real-life PB election data.