arXiv Machine Learning By Hao Li, Yasuyuki Tahara, Yuichi Sei

Beyond the Previous Layer: Residual Predictive Structure in Sparse MoE Routing

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arXiv:2609. 17940v1 Announce Type: new Abstract: Sparse mixture-of-experts models route each token through a sequence of expert selections.

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arXiv AI
Sep 3

Evidence for Shared Routing Geometry and Dynamics in Sparse Mixture-of-Experts

The paper investigates how routing decisions in sparse mixture-of-experts (MoE) models evolve across layers. By aligning router control subspaces with generalized orthogonal Procrustes analysis, the authors find that a single linear transition can predict routing states across depth with substantial accuracy, revealing a shared geometric structure. They further demonstrate that these canonical states preserve expert selection better than generic hidden representations and improve next‑step routing predictions, reducing negative log‑likelihood by up to 15.7% on OLMoE and 6.2% on Phi.

By Kirill Labzin, Stepan Kulibaba, Artem Dzhalilov, Artem Gorokhov
arXiv Machine Learning
Aug 27

Output Dilution: Redundant but Fragile Representations in MoE Models

The paper investigates how Mixture-of-Experts (MoE) models encode moral content compared to dense models. While linear probes can recover moral valence from almost all expert-layer combinations with high accuracy, these representations are far more fragile to activation noise, showing a 4.2‑fold drop in robustness. The authors attribute this fragility to output dilution: the MoE block averages across active experts, reducing the feedforward signal by nearly two orders of magnitude, which makes moral information vulnerable to perturbation even though routing remains stable.

By Orion Reblitz-Richardson
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
Sep 22

Efficient Mixture-of-Experts with Speculative Decoding via Expert Coactivation

The paper studies how the design of Mixture-of-Experts (MoE) routers affects inference speed when combined with Speculative Decoding (SD). It shows that routers promoting high expert coactivation reduce memory transfer costs and improve runtime. By integrating a global load‑balancing loss, shared experts, a consistency loss, and an autoregressive expert selection mechanism, the authors achieve a 21% throughput gain over baseline MoEs while preserving accuracy.

By Kumari Nishu, Han-Byul Kim, Santosh Chilkunda, Maxwell Horton, Arnav Kundu, Mohammad Samragh, Lauren Hannah, Mohammad Sekhavat, Nikhil Bhendawade, Manuel Ciosici, Iman Mirzadeh, Keivan Alizadeh Vahid, David Harrison, Irina Belousova, Mehrdad Farajtabar, Minsik Cho