Graph Neural Networks (GNNs) have emerged as one of the leading approaches for machine learning on graph-structured data. Despite their great success, critical computational challenges such as over-smoothing, over-squashing, and limited expressive power continue to impact the performance of GNNs. In this study, inspired from the time-reversal principle commonly utilized in classical and quantum physics, we reverse the time direction of the graph heat equation. The resulted reversing process yields a class of high pass filtering functions that enhance the sharpness of graph node features. Leveraging this concept, we introduce the Multi-Scaled Heat Kernel based GNN (MHKG) by amalgamating diverse filtering functions' effects on node features. To explore more flexible filtering conditions, we further generalize MHKG into a model termed G-MHKG and thoroughly show the roles of each element in controlling over-smoothing, over-squashing and expressive power. Notably, we illustrate that all aforementioned issues can be characterized and analyzed via the properties of the filtering functions, and uncover a trade-off between over-smoothing and over-squashing: enhancing node feature sharpness will make model suffer more from over-squashing, and vice versa. Furthermore, we manipulate the time again to show how G-MHKG can handle both two issues under mild conditions. Our conclusive experiments highlight the effectiveness of proposed models. It surpasses several GNN baseline models in performance across graph datasets characterized by both homophily and heterophily.

借鉴于经典和量子物理中常用的反时间原理，本研究颠倒了图热方程的时间方向，产生了一类高通滤波函数，提高了图节点特征的清晰度。基于此概念，引入了基于多尺度热核的图神经网络(MHKG)，通过综合不同的滤波函数对节点特征的影响，进一步将MHKG广义化为一种称为G-MHKG的模型，并全面展示了控制过度平滑、过度压缩和表现能力的各个元素的作用。本研究发现通过滤波函数的特性可以表征和分析上述问题，并揭示了过度平滑和过度压缩之间的权衡关系：提高节点特征的清晰度会使模型更容易过度压缩，反之亦然。此外，通过再次操作时间，展示了G-MHKG在较小条件下如何解决这两个问题。我们的实验结果证明了所提出模型的有效性，其在既具有同质性又具有异质性的图数据集上胜过了几个基线模型。

图神经网络中强化平滑与过度压缩的统一: 一种基于物理信息的方法及拓展