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arXiv 2503.03213stat.MLcs.LG
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Softmax门控混合专家模型的收敛速率

Convergence Rates for Softmax Gating Mixture of Experts

The University of Texas at Austin(德克萨斯大学奥斯汀分校)

Huy Nguyen, Nhat Ho, Alessandro Rinaldo

AI总结:

本文对配备标准softmax门控及其变体的混合专家模型进行了参数与专家估计的收敛性分析,证明满足强可辨识性条件的专家仅需多项式级数据,而线性专家需指数级数据。

摘要:

混合专家模型(MoE)近期作为一种有效框架出现,通过将复杂任务在多个被称为专家的专门子模型之间进行软划分,提升了机器学习模型的效率和可扩展性。MoE成功的关键在于自适应softmax门控机制,它负责确定每个专家对给定输入的相关性,并动态为专家分配相应权重。尽管在实践中被广泛使用,文献中一直缺乏关于softmax门控对MoE影响的全面研究。为弥补这一空白,本文在配备标准softmax门控或其变体(分别包括稠密到稀疏门控和分层softmax门控)的MoE下,对参数估计和专家估计进行了收敛性分析。此外,我们的理论也为设计样本高效的专家结构提供了有用见解。具体而言,我们证明估计满足我们提出的强可辨识性条件的专家(即常用的两层前馈网络)需要多项式级数量的数据点。形成鲜明对比的是,估计违反强可辨识性条件的线性专家,由于以偏微分方程语言表达的内在参数交互作用,必然需要指数级数量的数据点。所有理论结果均有严格的保证作为支撑。

英文摘要:

Mixture of experts (MoE) has recently emerged as an effective framework to advance the efficiency and scalability of machine learning models by softly dividing complex tasks among multiple specialized sub-models termed experts. Central to the success of MoE is an adaptive softmax gating mechanism which takes responsibility for determining the relevance of each expert to a given input and then dynamically assigning experts their respective weights. Despite its widespread use in practice, a comprehensive study on the effects of the softmax gating on the MoE has been lacking in the literature. To bridge this gap in this paper, we perform a convergence analysis of parameter estimation and expert estimation under the MoE equipped with the standard softmax gating or its variants, including a dense-to-sparse gating and a hierarchical softmax gating, respectively. Furthermore, our theories also provide useful insights into the design of sample-efficient expert structures. In particular, we demonstrate that it requires polynomially many data points to estimate experts satisfying our proposed \emph{strong identifiability} condition, namely a commonly used two-layer feed-forward network. In stark contrast, estimating linear experts, which violate the strong identifiability condition, necessitates exponentially many data points as a result of intrinsic parameter interactions expressed in the language of partial differential equations. All the theoretical results are substantiated with a rigorous guarantee.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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