š¤ AI Summary
In physical modeling, conventional Gaussian random fields (GRFs) fail to rigorously satisfy prescribed linear boundary constraintsāsuch as fixed values (Dirichlet), fixed derivatives (Neumann), or mixed-type (Robin) conditionsāleading to priors inconsistent with underlying physical laws. To address this, we propose the first general framework for constructing GRFs on multidimensional convex domains that *exactly* satisfy arbitrary-order continuous linear boundary constraints. Our method leverages orthogonal projection in function spaces combined with linear differential operator constraints to map an unconstrained GRF onto the subspace of functions adhering to the specified boundary conditions. This yields analytically exact enforcement of Dirichlet, Neumann, and Robin constraintsāunprecedented in prior GRF constructionsāand delivers physically consistent probabilistic priors. Experiments demonstrate substantial improvements in predictive accuracy and calibrated uncertainty quantification across applications including probabilistic numerical solving of PDEs, dynamical system discovery, and boundary-aware state estimation.
š Abstract
Boundary constraints in physical, environmental and engineering models restrict smooth states such as temperature to follow known physical laws at the edges of their spatio-temporal domain. Examples include fixed-state or fixed-derivative (insulated) boundary conditions, and constraints that relate the state and the derivatives, such as in models of heat transfer. Despite their flexibility as prior models over system states, Gaussian random fields do not in general enable exact enforcement of such constraints. This work develops a new general framework for constructing linearly boundary-constrained Gaussian random fields from unconstrained Gaussian random fields over multi-dimensional, convex domains. This new class of models provides flexible priors for modeling smooth states with known physical mechanisms acting at the domain boundaries. Simulation studies illustrate how such physics-informed probability models yield improved predictive performance and more realistic uncertainty quantification in applications including probabilistic numerics, data-driven discovery of dynamical systems, and boundary-constrained state estimation, as compared to unconstrained alternatives.