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Inter-Domain Gaussian Processes with Arbitrary Mean Functions in Factor Graphs
Proceedings of the 2nd International Conference on Probabilistic Numerics, PMLR 341:90-101, 2026.
Abstract
The modeling flexibility and expressivity of inter-domain Gaussian processes, enabled by applying arbitrary linear operators to a latent Gaussian process, is significant and desirable in robotics and probabilistic numerics communities. However, inter-domain Gaussian processes have not yet been available in a probabilistic message-passing formulation. In this paper, we formalize how to enable inter-domain observations for Gaussian processes in a variational message-passing framework. We develop a decoupled inter-domain variational sparse Gaussian process (dID-VSGP) model for univariate latent Gaussian processes with arbitrary mean functions, and derive the mean-field variational message-passing update rules that allow inference in this model. We validate our derivations in a shape exploration and modeling task, and by solution to a linear stochastic partial differential equation representative of physics-informed exploration. We confirm that our message-passing implementation maintains the same scaling complexity as the VSGP analytical solution. Our results further unify the analytical and message-passing approaches to variational inference and enable inter-domain observations in factor-graph Gaussian processes.