p ). The hyperparameters θ s = (σ fs , l s , σ n ), θ p = (σ fp , l p , σ n ), and θ sp = (σ fs , σ fp , l s , l p , σ n ) for the respective models are determined by maximizing their log-marginal likelihood over D using the L-BFGS algorithm with randomly sampled initial values. Our custom GPR model is based on respective code from the scikit-learn 52 implementation.