GraKerformer: A Transformer With Graph Kernel for Unsupervised Graph Representation Learning.

While highly influential in deep learning, especially in natural language processing, the Transformer model has not exhibited competitive performance in unsupervised graph representation learning (UGRL). Conventional approaches, which focus on local substructures on the graph, offer simplicity but often fall short in encapsulating comprehensive structural information of the graph. This deficiency leads to suboptimal generalization performance. To address this, we proposed the GraKerformer model, a variant of the standard Transformer architecture, to mitigate the shortfall in structural information representation and enhance the performance in UGRL. By leveraging the shortest-path graph kernel (SPGK) to weight attention scores and combining graph neural networks, the GraKerformer effectively encodes the nuanced structural information of graphs. We conducted evaluations on the benchmark datasets for graph classification to validate the superior performance of our approach.