通过重加权边来实现更公平的PageRank,不改网络结构只调边权重。
Fairness-aware PageRank via Edge Reweighting
- 重定义转移概率矩阵中的边权重以优化群体公平性。
- 微小权重调整即显著提升群体间排名公平性,效果优于现有方法。
- 适合关注算法公平性的网络分析与推荐系统研究者。
链接分析算法(如PageRank)通过节点连通性评估网络中个体的重要性。随着负责任AI的兴起,算法公平性问题日益重要。本文提出一种在原始网络拓扑不变的前提下,通过重加权转移矩阵中的边权重来实现群体公平性的新方法。目标是使群体间的原始PageRank分布与目标分布之间的公平损失最小化。我们引入一种考虑群体同质性的群体自适应公平性定义,基于带有群体偏置重启的随机游走进行建模。由于公平损失函数非凸,我们设计了一种高效的投影梯度下降法求解局部最优边权重。相比以往方法,本工作不新增边或修改重启向量,仅调整现有边的相对重要性。实验表明,极小的权重变化即可带来显著的公平性提升,优于当前主流基线方法。
原文摘要 · Abstract (English)
Link-analysis algorithms, such as PageRank, are instrumental in understanding the structural dynamics of networks by evaluating the importance of individual vertices based on their connectivity. Recently, with the rising importance of responsible AI, the question of fairness in link-analysis algorithms has gained traction. In this paper, we present a new approach for incorporating group fairness into the PageRank algorithm by reweighting the transition probabilities in the underlying transition matrix. We formulate the problem of achieving fair PageRank by seeking to minimize the fairness loss, which is the difference between the original group-wise PageRank distribution and a target PageRank distribution. We further define a group-adapted fairness notion, which accounts for group homophily by considering random walks with group-biased restart for each group. Since the fairness loss is non-convex, we propose an efficient projected gradient-descent method for computing locally-optimal edge weights. Unlike earlier approaches, we do not recommend adding new edges to the network, nor do we adjust the restart vector. Instead, we keep the topology of the underlying network unchanged and only modify the relative importance of existing edges. We empirically compare our approach with state-of-the-art baselines and demonstrate the efficacy of our method, where very small changes in the transition matrix lead to significant improvement in the fairness of the PageRank algorithm.
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