arXiv:2508.15378cs.LGcs.AI2025-08被引 1

提出EvoFormer模型,解决动态图表示学习中的结构偏差与突变盲区问题。

EvoFormer: Learning Dynamic Graph-Level Representations with Structural and Temporal Bias Correction

  • 引入结构感知注意力机制,基于节点结构角色编码缓解高连接度节点的采样偏差。
  • 通过三步时序建模策略,精准识别结构突变点,提升对快速演化事件的捕捉能力。
  • 适合需要高精度动态图分析的场景,如社交网络异常检测与演化趋势预测。

动态图级嵌入旨在捕捉网络结构的演化,这对建模真实世界场景至关重要。然而现有方法面临两个关键但未充分探索的问题:结构访问偏差,即随机游走采样过度强调高阶节点,导致结构表示冗余且噪声大;以及突发演化盲区,因时序建模僵化或过于简单,难以有效检测突然的结构变化,造成时间嵌入不一致。为此,我们提出EvoFormer,一种面向动态图级表示学习的演化感知Transformer框架。为缓解结构访问偏差,EvoFormer引入结构感知注意力模块,基于节点结构角色进行位置编码,实现全局结构差异的准确区分。为克服突发演化盲区,采用演化敏感时序模块,通过三步序列策略显式建模时间演化:(I) 随机游走时间戳分类,生成初始时间感知的图级嵌入;(II) 图级时序分割,将图流划分为反映结构一致性时期;(III) 段感知时序自注意力结合边演化预测任务,使模型能精确捕捉段边界并感知结构演化趋势,有效适应快速时序变化。在五个基准数据集上的广泛评估表明,EvoFormer在图相似性排序、时序异常检测和时序分割任务上均达到领先性能,验证了其在纠正结构与时序偏差方面的有效性。

原文摘要 · Abstract (English)

Dynamic graph-level embedding aims to capture structural evolution in networks, which is essential for modeling real-world scenarios. However, existing methods face two critical yet under-explored issues: Structural Visit Bias, where random walk sampling disproportionately emphasizes high-degree nodes, leading to redundant and noisy structural representations; and Abrupt Evolution Blindness, the failure to effectively detect sudden structural changes due to rigid or overly simplistic temporal modeling strategies, resulting in inconsistent temporal embeddings. To overcome these challenges, we propose EvoFormer, an evolution-aware Transformer framework tailored for dynamic graph-level representation learning. To mitigate Structural Visit Bias, EvoFormer introduces a Structure-Aware Transformer Module that incorporates positional encoding based on node structural roles, allowing the model to globally differentiate and accurately represent node structures. To overcome Abrupt Evolution Blindness, EvoFormer employs an Evolution-Sensitive Temporal Module, which explicitly models temporal evolution through a sequential three-step strategy: (I) Random Walk Timestamp Classification, generating initial timestamp-aware graph-level embeddings; (II) Graph-Level Temporal Segmentation, partitioning the graph stream into segments reflecting structurally coherent periods; and (III) Segment-Aware Temporal Self-Attention combined with an Edge Evolution Prediction task, enabling the model to precisely capture segment boundaries and perceive structural evolution trends, effectively adapting to rapid temporal shifts. Extensive evaluations on five benchmark datasets confirm that EvoFormer achieves state-of-the-art performance in graph similarity ranking, temporal anomaly detection, and temporal segmentation tasks, validating its effectiveness in correcting structural and temporal biases.

动态图时序建模结构偏差Transformer

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