arXiv Machine Learning By Ezza Ali, Sehrish Bibi, Momina Moetesum, Faisal Shafait

What We Keep of What We Forget: Replacement Operators and Routing Semantics in Training-Free MoE Expert Pruning

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The paper investigates training‑free pruning of Mixture‑of‑Experts (MoE) models, focusing on how to handle the computation when a router selects a pruned expert. It compares replacement operators from three families on several models (OLMoE, DeepSeek‑V2‑Lite, Moonlight, Granite) while keeping the pruning mask fixed, and introduces a new operator called the tilted novice. The study finds that no single operator consistently dominates, with performance varying by model, pruning level, and evaluation metric, and it proposes a five‑item checklist for reporting results.

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