---
title: "Participatory Budgeting Project Strength via Candidate Control"
authors:
  - "Piotr Faliszewski"
  - "Łukasz Janeczko"
  - "Dušan Knop"
  - "Jan Pokorný"
  - "Šimon Schierreich"
  - "Mateusz Słuszniak"
  - "Krzysztof Sornat"
doi: "10.24963/ijcai.2025/425"
url: "https://ijcai.org/proceedings/2025/425"
pdf: "https://ijcai.org/proceedings/2025/0425.pdf"
venue: "Proceedings of the Thirty-Fourth International Joint Conference on Artificial Intelligence"
year: 2025
pages: "3821-3829"
track: "Main Track"
keywords:
  - "Game Theory and Economic Paradigms: GTEP: Computational social choice"
---

# Participatory Budgeting Project Strength via Candidate Control

Piotr Faliszewski, Łukasz Janeczko, Dušan Knop, Jan Pokorný, Šimon Schierreich, Mateusz Słuszniak, Krzysztof Sornat

*Proceedings of the Thirty-Fourth International Joint Conference on Artificial Intelligence*, pages 3821-3829. DOI: [10.24963/ijcai.2025/425](https://doi.org/10.24963/ijcai.2025/425)

## Abstract

We study the complexity of candidate control in participatory budgeting elections. The goal of constructive candidate control is to ensure that a given candidate wins by either adding or deleting candidates from the election (in the destructive setting, the goal is to prevent a given candidate from winning). We show that such control problems are NP-hard to solve for many participatory budgeting voting rules, including Phragmén and Equal-Shares, but there are natural cases with polynomial-time algorithms. We also argue that control by deleting candidates is a useful tool for assessing the performance (or, strength) of initially losing projects, and we support this view with experiments on real-life PB instances.