In-processing User Constrained Dominant Sets for User-Oriented Fairness in Recommender Systems

TL;DR

This paper introduces In-UCDS, a novel in-processing framework that enhances user-oriented fairness in recommender systems by clustering disadvantaged users with similar advantaged users and adjusting their representations during training.

Contribution

The paper proposes a general in-processing approach using constrained dominant sets to improve fairness for disadvantaged users in recommender systems, applicable to any backbone model.

Findings

In-UCDS outperforms state-of-the-art fairness methods.

It improves fairness without sacrificing recommendation accuracy.

Experiments on three real datasets validate effectiveness.

Abstract

Recommender systems are typically biased toward a small group of users, leading to severe unfairness in recommendation performance, i.e., User-Oriented Fairness (UOF) issue. The existing research on UOF is limited and fails to deal with the root cause of the UOF issue: the learning process between advantaged and disadvantaged users is unfair. To tackle this issue, we propose an In-processing User Constrained Dominant Sets (In-UCDS) framework, which is a general framework that can be applied to any backbone recommendation model to achieve user-oriented fairness. We split In-UCDS into two stages, i.e., the UCDS modeling stage and the in-processing training stage. In the UCDS modeling stage, for each disadvantaged user, we extract a constrained dominant set (a user cluster) containing some advantaged users that are similar to it. In the in-processing training stage, we move the representations of disadvantaged users closer to their corresponding cluster by calculating a fairness loss. By combining the fairness loss with the original backbone model loss, we address the UOF issue and maintain the overall recommendation performance simultaneously. Comprehensive experiments on three real-world datasets demonstrate that In-UCDS outperforms the state-of-the-art methods, leading to a fairer model with better overall recommendation performance.