挑战GNN过平滑与过挤压的主流认知,指出实际性能下降主因是感受野信息不足。
Position: Don't be Afraid of Over-Smoothing And Over-Squashing
- 提出性能下降源于感受野信息贫乏,而非过平滑或过挤压
- 实验显示准确率与过平滑程度基本无关,最优深度仍很小
- 建议关注标签相关信息的局部化分布,指导模型设计
过去多年,图神经网络(GNN)研究广泛聚焦于过平滑与过挤压现象。本文挑战这一主流观点,认为这些现象对实际应用影响远小于假设。我们提出,性能下降常由感受野信息不足导致,而非过平滑。在多个标准基准数据集上的大量实验表明,准确率与过平滑程度基本无关,即使采用缓解技术,最优模型深度依然很小,凸显过平滑的非关键性。同样,我们质疑过挤压在实际中总是有害的判断。相反,我们认为标签相关信息常呈因子分解且局域于小范围k跳邻域,无需全局观察或长程交互搜索。实验显示,旨在缓解过挤压的架构干预未带来显著性能提升。本文呼吁理论研究范式转变,倡导通过统计方法分析学习任务与数据集,以更准确理解标签相关信息的局部化与因子分解特性。
原文摘要 · Abstract (English)
Over-smoothing and over-squashing have been extensively studied in the literature on Graph Neural Networks (GNNs) over the past years. We challenge this prevailing focus in GNN research, arguing that these phenomena are less critical for practical applications than assumed. We suggest that performance decreases often stem from uninformative receptive fields rather than over-smoothing. We support this position with extensive experiments on several standard benchmark datasets, demonstrating that accuracy and over-smoothing are mostly uncorrelated and that optimal model depths remain small even with mitigation techniques, thus highlighting the negligible role of over-smoothing. Similarly, we challenge that over-squashing is always detrimental in practical applications. Instead, we posit that the distribution of relevant information over the graph frequently factorises and is often localised within a small k-hop neighbourhood, questioning the necessity of jointly observing entire receptive fields or engaging in an extensive search for long-range interactions. The results of our experiments show that architectural interventions designed to mitigate over-squashing fail to yield significant performance gains. This position paper advocates for a paradigm shift in theoretical research, urging a diligent analysis of learning tasks and datasets using statistics that measure the underlying distribution of label-relevant information to better understand their localisation and factorisation.
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