Truthful aggregation of budget proposals with proportionality guarantees

Ioannis Caragiannis, George Christodoulou, Nicos Protopapas

Abstract: Highlights•Participatory budgeting engages community members with public decision-making.•Aggregating budget proposals proportionally is susceptible to strategic manipulation.•Incentive-compatible mechanisms for budget aggregation may lead to unfair allocations.•We compare incentive-compatible mechanisms with the proportional allocation, in the worst case.•We provide effectively optimal mechanisms aggregating a budget over two and three projects.