🤖 AI Summary
To address the challenges of ineffective gradient integration and computationally intensive Bayesian inference in deep Gaussian processes (DGPs) for nonstationary computer experiments, this paper proposes Gradient-enhanced Deep Gaussian Processes (Grad-DGP). Grad-DGP employs multi-layer latent Gaussian processes to perform nonlinear input-space warping and gradient-aware modeling. It establishes, for the first time, a complete Bayesian framework supporting gradient embedding—encompassing both gradient-augmented training and gradient posterior prediction. To overcome the O(N³) computational bottleneck, we incorporate an optional Vecchia sparse approximation. Extensive evaluations on multiple nonstationary simulation benchmarks demonstrate that Grad-DGP significantly outperforms both gradient-augmented standard GPs and conventional DGPs, confirming the modeling benefits of incorporating gradient information into deep stochastic mappings. The methodology is publicly available as the R package *deepgp*.
📝 Abstract
Deep Gaussian processes (DGPs) are popular surrogate models for complex nonstationary computer experiments. DGPs use one or more latent Gaussian processes (GPs) to warp the input space into a plausibly stationary regime, then use typical GP regression on the warped domain. While this composition of GPs is conceptually straightforward, the functional nature of the multi-dimensional latent warping makes Bayesian posterior inference challenging. Traditional GPs with smooth kernels are naturally suited for the integration of gradient information, but the integration of gradients within a DGP presents new challenges and has yet to be explored. We propose a novel and comprehensive Bayesian framework for DGPs with gradients that facilitates both gradient-enhancement and gradient posterior predictive distributions. We provide open-source software in the "deepgp" package on CRAN, with optional Vecchia approximation to circumvent cubic computational bottlenecks. We benchmark our DGPs with gradients on a variety of nonstationary simulations, showing improvement over both GPs with gradients and conventional DGPs.