In recent years, there has been a significant amount of research focused on expanding the expressivity of Graph Neural Networks (GNNs) beyond the Weisfeiler-Lehman (1-WL) framework. While many of these studies have yielded advancements in expressivity, they have frequently come at the expense of decreased efficiency or have been restricted to specific types of graphs. In this study, we investigate the expressivity of GNNs from the perspective of graph search. Specifically, we propose a new vertex colouring scheme and demonstrate that classical search algorithms can efficiently compute graph representations that extend beyond the 1-WL. We show the colouring scheme inherits useful properties from graph search that can help solve problems like graph biconnectivity. Furthermore, we show that under certain conditions, the expressivity of GNNs increases hierarchically with the radius of the search neighbourhood. To further investigate the proposed scheme, we develop a new type of GNN based on two search strategies, breadth-first search and depth-first search, highlighting the graph properties they can capture on top of 1-WL. Our code is available at https://github.com/seanli3/lvc.

最近几年来，有大量的研究专注于扩展图神经网络（GNNs）的表达能力，超越Weisfeiler-Lehman (1-WL)框架。在这项研究中，我们从图搜索的角度探讨了GNNs的表达能力，提出了一种新的顶点着色方案，并证明经典的搜索算法可以高效地计算超越1-WL的图表示。我们展示了这种着色方案从图搜索中继承的有用特性，可以帮助解决图的双连通性问题。此外，我们还展示了在某些条件下，GNNs的表达能力随着搜索邻域的半径逐层递增。为了进一步研究所提出的方案，我们基于广度优先搜索和深度优先搜索开发了一种新类型的GNN，突出了它们在1-WL之上所能捕捉到的图属性。

本地顶点着色图神经网络