BAMFair: Barycenter Aligned Mediation for Fairness Across Multiple Sensitive Attributes

Abstract

Achieving fairness in machine learning models while maintaining high accuracy is an important but complex task, especially when handling multiple sensitive attributes. Traditional fairness methods often struggle to eliminate bias within subgroups divided by sensitive attributes. Several key challenges have been identified in this context: (1) Multiple sensitive attribute scalability challenge, where methods fail to ensure fairness as the number of sensitive attributes increases, despite scenarios with multiple sensitive attributes being prevalent in real-world applications; (2) Multiple objective optimization conflict challenge, where simultaneously optimizing for accuracy, fairness, and other relevant objectives leads to conflicting gradient updates, causing suboptimal performance. To address these challenges, we propose BAMFair, a Barycenter Aligned Mediation framework for fairness across multiple sensitive attributes. It comprises two core modules: a Global Barycentric Alignment (GBA) module and a Nash Fairness Mediator (NFM) module. Specifically, GBA innovatively introduces a global fair barycenter and minimizes the distances from subgroups divided by sensitive attributes to it, providing a scalable and efficient solution for fairness optimization across multiple sensitive attributes. Subsequently, NFM negotiates an agreement among inconsistent gradient updates between different objectives. Extensive experiments on four real-world datasets validate that BAMFair outperforms state-of-the-art methods in scenarios with multiple sensitive attributes.