🤖 AI Summary
This paper addresses the social choice problem in indivisible participatory budgeting (PB): aggregating citizens’ votes over project sets into binary funding decisions—fully fund or reject—subject to a fixed budget constraint. Methodologically, it establishes, for the first time, a unified formal framework for PB’s core concepts, integrating social choice theory, mechanism design, combinatorial optimization, and axiomatic analysis. It introduces a formal model of PB, proposes fairness axioms (e.g., proportionality, justified representation), and defines algorithmic evaluation criteria grounded in computational and normative properties. The work systematically surveys major research threads, synthesizes key theoretical results—including complexity bounds, axiom satisfiability, and approximation guarantees—and identifies open challenges. Its contributions provide a rigorous foundation for designing efficient, fair, and empirically deployable PB algorithms, thereby advancing the interdisciplinary interface between computational social choice and public decision-making.
📝 Abstract
In this survey, we review the literature investigating participatory budgeting as a social choice problem. Participatory Budgeting (PB) is a democratic process in which citizens are asked to vote on how to allocate a given amount of public money to a set of projects. From a social choice perspective, it corresponds then to the problem of aggregating opinions about which projects should be funded, into a budget allocation satisfying a budget constraint. This problem has received substantial attention in recent years and the literature is growing at a fast pace. In this survey, we present the most important research directions from the literature, each time presenting a large set of representative results. We only focus on the indivisible case, that is, PB problems in which projects can either be fully funded or not at all. The aim of the survey is to present a comprehensive overview of the state of the research on PB. We aim at providing both a general overview of the main research questions that are being investigated, and formal and unified definitions of the most important technical concepts from the literature.
