arXiv Machine Learning

GaP-MoE : Explicit Expert Specialization in Mixture-of-Experts via Orthogonal Gradient Accumulation and Projection

GaP-MoE introduces a method for explicit expert specialization in Sparse Mixture-of-Experts models by manipulating expert output gradients instead of adding auxiliary loss terms. The technique selects a leader expert from the top‑K routed experts and projects follower experts’ gradients onto the orthogonal complement of the leader’s recent gradients, reducing directional overlap. Experiments on fine‑tuning BERT for GLUE and pretraining GPT‑2 on various corpora show that GaP‑MoE matches or surpasses standard SMoE performance while remaining a drop‑in module.

arXiv Machine Learning
Sep 4

Towards a Statistical Understanding of Mixture-of-Experts

The paper presents a statistical framework for Mixture-of-Experts (MoE) models, treating them as localized aggregation systems. It derives oracle risk bounds that separate approximation, expert‑learning, and router‑estimation errors for both dense and sparse routing with evolving experts. The authors also analyze how sparse Top‑K routing balances computational cost with performance, interpret gating geometrically, and explain how shared experts can capture common predictive structure while allowing routed experts to focus on local residuals.

By Siyuan He, Bokai Yang, Jie Hu, Ziwen Gao, Yuhong Yang
arXiv Machine Learning
Oct 3

MoRA: MoE Pruning via Router Bias Learning and Expert Approximation

MoRA is a framework for pruning Mixture-of-Experts (MoE) models by learning a router bias for each expert and optimizing it with a language‑modeling loss and a routing‑diversity regularizer. The learned biases sharpen routing distributions to identify critical experts and encourage diverse routing preferences. After pruning, MoRA uses an expert approximation mechanism that approximates the outputs of pruned experts with affine transformations of remaining experts, further improving performance.

By Yushuai Sun, Zikun Zhou, Lin Gao, Jun Yu, Wenjie Pei
arXiv Computation and Language
Aug 28

Meta-Learning Where to Allocate Experts: Task-Conditioned Layer-Wise Compression for MoEs

MetaNet is a support‑set controller that predicts, for each layer of a Mixture‑of‑Experts model, an expert‑retention threshold and a bounded routing bias while keeping the backbone, experts, and router frozen. On DeepSeek‑MoE‑16B‑Chat, MetaNet offers a tunable trade‑off between accuracy and expert activation: a conservative setting activates 3.61 experts on average (40% fewer than a fixed k=6) with comparable MMLU accuracy, whereas an aggressive setting activates only 2.28 experts (62% fewer) with a modest accuracy drop. The MMLU‑trained controller also transfers to C‑Eval, activating 2.90 experts on average (52% fewer than fixed k=6) at 0.386 accuracy.

By Rongfeng Wang, Shichao Weng, Zhiqiang Wang, Xinyu Liu, Yang Yi, Peilong Zhou, Hongwei Tang
arXiv Machine Learning
Aug 27

Ban&Pick: Enhancing Performance and Efficiency of MoE-LLMs via Smarter Routing

The paper introduces Ban&Pick, a post‑training, plug‑and‑play routing strategy for Sparse Mixture‑of‑Experts large language models. It identifies and reinforces a small group of highly influential experts while dynamically pruning redundant ones, leading to accuracy gains across math, code, and reasoning benchmarks. Experiments on DeepSeek and Qwen3 show notable performance improvements and a 1.25× inference speedup without retraining or architectural changes.

By Yuanteng Chen, Peisong Wang, Yuantian Shao, Nanxin Zeng, Chang Xu, Jian Cheng
arXiv Machine Learning
Oct 7

MASKerade: Token-Routed Mask Experts for Dense-to-MoE Upcycling

MASKerade is a new dense‑to‑MoE training method that learns experts as sparse subnetworks of a frozen pretrained feed‑forward network (FFN) using binary masks. A token‑level router selects which masked FFNs to execute, and both the router and mask scores are jointly optimized while the underlying FFN weights remain unchanged. In experiments on five vision‑language benchmarks with Qwen and Gemma backbones, a configuration of four 2:4 experts with top‑2 routing achieved the best performance among compared baselines, demonstrating that mask learning over frozen weights is a practical alternative for constructing token‑routed MoE experts.

By Mingyuan Zhang, Yue Bai, Zhongruo Wang, Yupin Huang, Yiyang Huang, Hailing Wang, Huimin Zeng, Yun Fu
arXiv Machine Learning
Oct 3

Redundancy Meets Synergy: Dependency-aware Expert Selection for MoE via Submodular Optimization

The paper introduces DS-MoE, a framework that selects a compact subset of experts in Mixture-of-Experts models using difference-of-submodular (DS) optimization. It analyzes the loss degradation via a second-order Taylor expansion to uncover redundancy and synergy among experts, and formulates the selection objective to decouple these effects. A majorization-minimization algorithm with monotonicity guarantees efficiently identifies the optimal subset, and experiments show DS-MoE outperforms state‑of‑the‑art baselines.

By Zheng Lin, Shaoke Fang, Yuxin Zhang, Jinfeng Xu, Zihan Fang, Zhe Chen, Wei Ni, Jun Luo, Symeon Chatzinotas