Graph-Based Audits for Meek Single Transferable Vote Elections

TL;DR

This paper introduces a graph-based framework for risk-limiting audits of algorithmic election rules like STV, enabling flexible, chronology-agnostic verification of election outcomes by analyzing possible sequences of eliminations.

Contribution

It proposes a novel graph-based method to audit complex election rules such as STV, overcoming previous limitations related to election sequence dependencies.

Findings

Framework allows flexible auditing of STV elections.

Verifies election outcomes without fixing elimination order.

Enables chronology-agnostic election audits.

Abstract

In the context of election security, a Risk-Limiting Audit (RLA) is a statistical framework that uses a minimal partial recount of the ballots to guarantee that the results of the election were correctly reported. A generalized RLA framework has remained elusive for algorithmic election rules such as the Single Transferable Vote (STV) rule, because of the dependence of these rules on the chronology of eliminations and elections leading to the outcome of the election. This paper proposes a new graph-based approach to audit these algorithmic election rules, by considering the space of all possible sequences of elections and eliminations. If we fix a subgraph of this universal space ahead of the audit, a sufficient strategy is to verify statistically that the true election sequence does not leave the fixed subgraph. This makes for a flexible framework to audit these elections in a chronology-agnostic way.