A neural network–Gaussian process model sends structured input through a neural network before applying a Gaussian process mean function and kernel. The network acts as a feature extractor, learning representations that make similarity calculations more useful while preserving uncertainty-calibrated predictions. section 13.3.1
The combined model works by:
- Transforming structured inputs into numerical features with layered computations. section 13.3.1
- Feeding the transformed features to the GP mean and covariance modules, which still produce a multivariate normal distribution. section 13.3.2
- Optimizing neural-network weights alongside GP mean, kernel, likelihood, and other hyperparameters by minimizing negative marginal log likelihood. section 13.3.1
MNIST feature extraction
A four-layer ReLU network maps each 784-dimensional MNIST input to two features. The learned two-dimensional representation clusters equal labels and forms a label gradient, giving the GP a smoother space to model. section 13.3.2
