Complexity of Manipulation, Bribery, and Campaign Management in Bucklin and Fallback Voting

TL;DR

This paper investigates the computational complexity of manipulation, bribery, and campaign management in Bucklin and fallback voting systems, revealing their resistance levels and computational challenges in various scenarios.

Contribution

It provides a comprehensive analysis of the resistance of Bucklin and fallback voting to manipulation and bribery, filling gaps in understanding their computational vulnerabilities.

Findings

Bucklin and fallback voting are NP-hard to manipulate and bribe in many scenarios.

The paper identifies specific conditions under which these voting systems resist control.

New complexity results for campaign management problems in these voting systems.

Abstract

A central theme in computational social choice is to study the extent to which voting systems computationally resist manipulative attacks seeking to influence the outcome of elections, such as manipulation (i.e., strategic voting), control, and bribery. Bucklin and fallback voting are among the voting systems with the broadest resistance (i.e., NP-hardness) to control attacks. However, only little is known about their behavior regarding manipulation and bribery attacks. We comprehensively investigate the computational resistance of Bucklin and fallback voting for many of the common manipulation and bribery scenarios; we also complement our discussion by considering several campaign management problems for Bucklin and fallback.