arXiv:2608.25741cs.LGcs.CL2026-08

图文联合训练时,文本教师无法有效提升图神经网络性能。

Why Does Graph Learning Fail to Fully Benefit from a Text Teacher?

论文配图:Why Does Graph Learning Fail to Fully Benefit from a Text Teacher?
图 1 · 摘自论文原文
  • 用交替优化让语言模型与图网络协同学习
  • 发现六种因素导致文本知识未能有效传递
  • 适合研究多模态图学习的失效机制

图神经网络(GNN)广泛用于表示实体间的复杂关系。本文研究一种融合自监督方法与交替优化的多模态模型:前者使预训练的GNN编码器可直接应用于节点特征维度不同的新数据集,无需重训练或对齐数据;后者在E-step更新语言模型模块,在M-step更新GNN模块,而非端到端联合训练大语言模型与大规模图。尽管预期性能提升,但组合模型未显著改善预测效果。我们识别出六个关键因素:(1) E-step中的外部锚点存在强度-安全权衡——过弱无作用,过强损害图表示;(2) 语言模型的知识未直接注入GCN嵌入Z;(3) M-step构建的表示空间未与E-step教师空间目标一致,导致分类性能妥协;(4) GCN传播将节点自身文本信息与其邻居信息平均化;(5) 余弦对齐不保证分类判别性轴,更强几何对齐未必改善决策边界;(6) M-step中保持源侧自监督几何的力与向教师锚点靠拢的力相冲突。通过分阶段实验验证了这些现象,系统分析了教师信号衰减原因。

原文摘要 · Abstract (English)

Graph neural networks (GNNs) are widely used to represent complex interactions and relationships among entities. We investigate a multimodal model that combines two complementary ideas: a self-supervised method that enables a GNN encoder pretrained on one dataset to operate directly on another dataset with a different node-feature dimensionality, without rebuilding the model or realigning the data; and an alternating optimization method that updates a language-model module in an E-step and a GNN module in an M-step, rather than jointly training a large language model and a GNN end to end on a large graph. Despite expectations, the combined model did not sufficiently improve predictive performance. We identify six factors: (1) an external anchor in the E-step has a strength-safety trade-off: a weak anchor has little effect, whereas an overly strong anchor can damage the graph representation; (2) the knowledge of the E-step teacher is not injected directly into the GCN embedding Z; (3) the representation space constructed in the M-step is not optimized for the same objective as the E-step teacher space, resulting in a compromise representation for target classification; (4) GCN propagation averages a node's own textual information with information from its neighbors; (5) cosine alignment does not guarantee axes that are discriminative for classification, so stronger geometric alignment with the E-step text anchor need not sufficiently improve the target decision boundary or classification performance; and (6) the force that preserves the source-side self-supervised geometry in the M-step conflicts with the force that moves the representation toward the E-step teacher. We support these observations through a staged set of experiments that varies the influence of the E-step.

图神经网络多模态学习知识迁移

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