Train a cheap neural surrogate globally, then use an ensemble or bootstrap covariance to identify inputs near the estimated upper-tail boundary and inputs where high-fidelity correction is uncertain. Fit a Tikhonov-regularized residual model on the acquired expensive labels and use the corrected predictor for CVaR estimation or risk-constrained optimization. The acquisition policy deliberately ignores easy central-region samples unless they influence the tail threshold.
Replace a finite-dimensional latent prior for fields or trajectories with a continuous flow acting on function coefficients in a separable Hilbert space. A Gaussian reference with an explicit covariance spectrum is transformed by a learned vector field, so the model can represent smooth, non-isotropic function distributions while sharing parameters across discretization resolutions.
Run Metropolis-Hastings directly on neural architectures modulo permutations of structurally exchangeable hidden units, channels, or experts rather than treating every labelled representation as a distinct architecture. Correct the proposal ratio using representation-orbit sizes, so architectures with many internal symmetries receive the intended posterior mass.
Reparameterize all Bayesian neural-network weights by a bounded latent vector in the unit ball and use a simple ball-constrained MCMC kernel instead of unconstrained HMC or random-walk sampling. A radial diffeomorphism expands points near the ball boundary into arbitrarily large weights, preserving heavy-tailed posterior mass while preventing the sampler from numerically wandering through an unbounded parameter space.