HEAPr: Hessian-based Efficient Atomic Expert Pruning in Output Space
To address the high memory overhead of Mixture-of-Experts (MoE) models due to their large parameter count and the significant accuracy degradation caused by existing expert-level pruning methods, this paper proposes a fine-grained atomic expert pruning framework. Its core innovation lies in the first-ever mapping of Hessian information from the expert parameter space to the atomic expert output space—reducing computational complexity to *O(d²)*—and leveraging the Optimal Brain Surgeon principle to estimate atomic expert importance via forward/backward passes on a small calibration dataset. Evaluated on DeepSeek-MoE and Qwen-MoE, the method achieves 20–25% model compression with negligible accuracy loss while reducing inference FLOPs by approximately 20%, substantially improving MoE model deployment efficiency.