发现异构图神经网络存在拓扑偏见,提出新方法有效缓解。
Exploring Topological Bias in Heterogeneous Graph Neural Networks
- 用元权重和PageRank构建节点映射,揭示拓扑偏见
- 在3个公开数据集上提升性能并减少偏差
- 适合研究图神经网络公平性与鲁棒性的读者
图神经网络(GNN)在处理图结构数据时,常因半监督学习中标签稀疏而表现出对特定节点的性能偏见。已有研究多聚焦于同构图,较少关注异构图神经网络(HGNNs)中的拓扑偏见。本文首先通过元权重调整异构图邻接矩阵,结合PageRank与节点标签信息构建投影,该投影能有效将节点映射为与模型性能强相关的值,无论是否存在同类型连接,在多个数据集上均验证了拓扑偏见的普遍性。为缓解此偏见,提出基于节点映射值差异的去偏结构,并与原始图结构联合用于对比学习。在三个公开数据集上的实验表明,所提方法显著提升了HGNNs性能并降低了偏差。
原文摘要 · Abstract (English)
Graph Neural Networks (GNNs) are characterized by their capacity of processing graph-structured data. However, due to the sparsity of labels under semi-supervised learning, they have been found to exhibit biased performance on specific nodes. This kind of bias has been validated to correlate with topological structure and is considered as a bottleneck of GNNs' performance. Existing work focuses on the study of homogeneous GNNs and little attention has been given to topological bias in Heterogeneous Graph Neural Networks (HGNNs). In this work, firstly, in order to distinguish distinct meta relations, we apply meta-weighting to the adjacency matrix of a heterogeneous graph. Based on the modified adjacency matrix, we leverage PageRank along with the node label information to construct a projection. The constructed projection effectively maps nodes to values that strongly correlated with model performance when using datasets both with and without intra-type connections, which demonstrates the universal existence of topological bias in HGNNs. To handle this bias, we propose a debiasing structure based on the difference in the mapped values of nodes and use it along with the original graph structure for contrastive learning. Experiments on three public datasets verify the effectiveness of the proposed method in improving HGNNs' performance and debiasing.
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