Manifold GCN: Diffusion-based Convolutional Neural Network for Manifold-valued Graphs
Modeling graph-structured data residing on Riemannian manifolds poses challenges in preserving intrinsic geometric structure while ensuring equivariance under both node permutations and manifold isometries. Method: We propose the first equivariant graph neural network layer that jointly incorporates manifold diffusion modeling and nonlinear equivariant mapping in tangent spaces. The layer defines graph convolution via the manifold diffusion equation and constructs an equivariant multilayer perceptron in the tangent space at each node, enabling native support for arbitrary graph topologies and sizes. Contribution/Results: Our layer rigorously satisfies equivariance under node permutations and Riemannian isometries, and uniformly accommodates diverse Riemannian manifolds—including spheres, hyperbolic spaces, and triangulated surfaces—by embedding strong geometric inductive biases. Experiments on synthetic manifold graph datasets and a real-world Alzheimer’s disease classification task using right hippocampal triangular meshes demonstrate performance competitive with or superior to state-of-the-art specialized methods, alongside significantly improved generalization.