Strategic Voting in the Context of Negotiating Teams

TL;DR

This paper explores strategic voting in negotiating teams, presenting algorithms for manipulation detection and success under various voting rules, highlighting computational complexities and solutions.

Contribution

It introduces polynomial-time algorithms for manipulation detection in positional scoring and approval rules, and addresses computational hardness with approximate solutions for Borda.

Findings

Polynomial-time algorithm for manipulation with positional scoring rules

Manipulation is tractable with approval rules for coalitions

Borda rule manipulation is computationally hard, but approximate solutions are possible

Abstract

A negotiating team is a group of two or more agents who join together as a single negotiating party because they share a common goal related to the negotiation. Since a negotiating team is composed of several stakeholders, represented as a single negotiating party, there is need for a voting rule for the team to reach decisions. In this paper, we investigate the problem of strategic voting in the context of negotiating teams. Specifically, we present a polynomial-time algorithm that finds a manipulation for a single voter when using a positional scoring rule. We show that the problem is still tractable when there is a coalition of manipulators that uses a x-approval rule. The coalitional manipulation problem becomes computationally hard when using Borda, but we provide a polynomial-time algorithm with the following guarantee: given a manipulable instance with k manipulators, the algorithm finds a successful manipulation with at most one additional manipulator. Our results hold for both constructive and destructive manipulations.