On DeepSeekMoE: Statistical Benefits of Shared Experts and Normalized Sigmoid Gating

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Hauptverfasser: Nguyen, Huy, Doan, Thong T., Pham, Quang, Bui, Nghi D. Q., Ho, Nhat, Rinaldo, Alessandro
Format: Preprint
Veröffentlicht: 2025
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author Nguyen, Huy
Doan, Thong T.
Pham, Quang
Bui, Nghi D. Q.
Ho, Nhat
Rinaldo, Alessandro
author_facet Nguyen, Huy
Doan, Thong T.
Pham, Quang
Bui, Nghi D. Q.
Ho, Nhat
Rinaldo, Alessandro
contents Mixture of experts (MoE) methods are a key component in most large language model architectures, including the recent series of DeepSeek models. Compared to other MoE implementations, DeepSeekMoE stands out because of two unique features: the deployment of a shared expert strategy and of the normalized sigmoid gating mechanism. Despite the prominent role of DeepSeekMoE in the success of the DeepSeek series of models, there have been only a few attempts to justify theoretically the value of the shared expert strategy, while its normalized sigmoid gating has remained unexplored. To bridge this gap, we undertake a comprehensive theoretical study of these two features of DeepSeekMoE from a statistical perspective. We perform a convergence analysis of the expert estimation task to highlight the gains in sample efficiency for both the shared expert strategy and the normalized sigmoid gating, offering useful insights into the design of expert and gating structures. To verify empirically our theoretical findings, we carry out several experiments on both synthetic data and real-world datasets for (vision) language modeling tasks. Finally, we conduct an extensive empirical analysis of the router behaviors, ranging from router saturation, router change rate, to expert utilization.
format Preprint
id arxiv_https___arxiv_org_abs_2505_10860
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On DeepSeekMoE: Statistical Benefits of Shared Experts and Normalized Sigmoid Gating
Nguyen, Huy
Doan, Thong T.
Pham, Quang
Bui, Nghi D. Q.
Ho, Nhat
Rinaldo, Alessandro
Machine Learning
Mixture of experts (MoE) methods are a key component in most large language model architectures, including the recent series of DeepSeek models. Compared to other MoE implementations, DeepSeekMoE stands out because of two unique features: the deployment of a shared expert strategy and of the normalized sigmoid gating mechanism. Despite the prominent role of DeepSeekMoE in the success of the DeepSeek series of models, there have been only a few attempts to justify theoretically the value of the shared expert strategy, while its normalized sigmoid gating has remained unexplored. To bridge this gap, we undertake a comprehensive theoretical study of these two features of DeepSeekMoE from a statistical perspective. We perform a convergence analysis of the expert estimation task to highlight the gains in sample efficiency for both the shared expert strategy and the normalized sigmoid gating, offering useful insights into the design of expert and gating structures. To verify empirically our theoretical findings, we carry out several experiments on both synthetic data and real-world datasets for (vision) language modeling tasks. Finally, we conduct an extensive empirical analysis of the router behaviors, ranging from router saturation, router change rate, to expert utilization.
title On DeepSeekMoE: Statistical Benefits of Shared Experts and Normalized Sigmoid Gating
topic Machine Learning
url https://arxiv.org/abs/2505.10860