Understanding Graph Transformers by Generalized Propagation

21 Sept 2023 (modified: 11 Feb 2024)Submitted to ICLR 2024EveryoneRevisionsBibTeX
Primary Area: learning on graphs and other geometries & topologies
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Keywords: geometric deep learning; graph transformer; discrete ricci curvature
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Abstract: Graph Transformers (GTs) have recently shown stellar performance on various graph learning benchmarks, which is typically attributed to their underlying global self-attention mechanism. In this paper, we use generalized propagation graphs, constructed through two abstract configurable functions and offering a unified view across various GNN models used in the literature. We show that by con- figuring the two abstract functions governing the generation of propagation graph, one could recover the most popular GNN models including graph Transformers, message-passing neural networks (MPNNs), as well as various forms of graph rewiring. We show that the expressivity of the instances of our framework depends on one of the governing functions (the adjacency function). Empirical results con- firm our theory: by keeping the adjacency function while removing self-attention, the state-of-the-art GT maintains its performance. In other words, by designing appropriate adjacency functions, one could construct novel GNN models with di- verse expressive power. We also study the geometric properties of the propagation graphs across a wide range of models, using a novel extension the Ollivier-Ricci curvature to weighted digraphs.
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Submission Number: 3922
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