Participatory Budgeting with Project Groups

Abstract:We study a generalization of the standard approval-based model of participatory budgeting (PB), in which voters are providing approval ballots over a set of predefined projects and---in addition to a global budget limit, there are several groupings of the projects, each group with its own budget limit. We study the computational complexity of identifying project bundles that maximize voter satisfaction while respecting all budget limits. We show that the problem is generally intractable and describe efficient exact algorithms for several special cases, including instances with only few groups and instances where the group structure is close to be hierarchical, as well as efficient approximation algorithms. Our results could allow, e.g., municipalities to hold richer PB processes that are thematically and geographically inclusive.

25 pages, 3 tables. An extended abstract of this work appears in IJCAI 2021. This is the author's version of the paper published in JCSS 156: 103702 (2026); it differs only in formatting and minor editorial changes

Computer Science and Game Theory (cs.GT); Artificial Intelligence (cs.AI); Data Structures and Algorithms (cs.DS); Multiagent Systems (cs.MA)

arXiv:2012.05213 [cs.GT]

(or arXiv:2012.05213v2 [cs.GT] for this version)

https://doi.org/10.1016/j.jcss.2025.103702 DOI(s) linking to related resources