🤖 AI Summary
While multi-model ensembles in randomized smoothing (RS) improve ℓ₂-robustness certification radii, they incur substantial training and certification overhead and neglect inter-classifier collaboration.
Method: We propose Multi-Head Ensemble Smoothing (ME-Smooth), a novel RS framework that deploys multiple parallel noise-injection paths and classification heads within a single deep neural network. It jointly optimizes feature perturbation robustness and decision diversity, introducing the multi-head architecture to RS for the first time. This design decouples noise-robust feature modeling from classification decisions, eliminating additional inference cost.
Results: On CIFAR-10 and an ImageNet subset, ME-Smooth achieves up to 8.2% higher certified accuracy compared to standard RS baselines. At equal certified ℓ₂ radii, it significantly outperforms both single-head RS and state-of-the-art certified defense methods.