SPADE — Diffusion Surrogates for Offline Optimization

Support-Proximity Augmented Diffusion Estimation (SPADE) models the forward likelihood \(p(y\mid x)\) with a calibrated conditional diffusion model, then adds a k-nearest-neighbour support prior so an offline optimizer cannot exploit regions the data never covered. It reaches state-of-the-art results on Design-Bench and language-model optimization.