🤖 AI Summary
This work proposes the Ens-CGP framework to establish a unified probabilistic representation for ensemble data, bridging the theoretical gap among ensemble methods, variational inference, and Gaussian processes. By treating empirical ensemble moments as (possibly low-rank) Gaussian priors, the approach constructs a conditional Gaussian process (CGP) through exact Bayesian conditioning. The framework explicitly separates representation—progressing from GP to CGP to Ens-CGP—from computational algorithms such as the ensemble Kalman filter (EnKF), thereby revealing the common probabilistic foundation underlying Kalman filtering, maximum a posteriori (MAP) estimation, and RKHS regularized regression under conditional Gaussian laws. This study provides a rigorous probabilistic basis for ensemble-based inference and, for the first time, unifies the probabilistic, variational, and ensemble perspectives at both geometric and representational levels.
📝 Abstract
We formulate Ensemble-Conditional Gaussian Processes (Ens-CGP), a finite-dimensional synthesis that centers ensemble-based inference on the conditional Gaussian law. Conditional Gaussian processes (CGP) arise directly from Gaussian processes under conditioning and, in linear-Gaussian settings, define the full posterior distribution for a Gaussian prior and linear observations. Classical Kalman filtering is a recursive algorithm that computes this same conditional law under dynamical assumptions; the conditional Gaussian law itself is therefore the underlying representational object, while the filter is one computational realization. In this sense, CGP provides the probabilistic foundation for Kalman-type methods as well as equivalent formulations as a strictly convex quadratic program (MAP estimation), RKHS-regularized regression, and classical regularization. Ens-CGP is the ensemble instantiation of this object, obtained by treating empirical ensemble moments as a (possibly low-rank) Gaussian prior and performing exact conditioning. By separating representation (GP ->CGP ->Ens-CGP) from computation (Kalman filters, EnKF variants, and iterative ensemble schemes), the framework links an earlier-established representational foundation for inference to ensemble-derived priors and clarifies the relationships among probabilistic, variational, and ensemble perspectives.